Crystallographic and optical study of LiNb1 − xTaxO3

Huband, S.; Keeble, D.S.; Zhang, N.; Glazer, A.M.; Bartasyte, A.; Thomas, P.A.

doi:10.1107/S2052520617004711

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ISSN: 2052-5206

Volume 73| Part 3| June 2017| Pages 498-506

https://doi.org/10.1107/S2052520617004711

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Crystallographic and optical study of LiNb_1 − xTa_xO₃

S. Huband,^a ^* D. S. Keeble,^a,^b N. Zhang,^c A. M. Glazer,^a,^d A. Bartasyte ^e and P. A. Thomas ^a

^aDepartment of Physics, University of Warwick, Coventry, West Midlands CV4 7AL, England, ^bDiamond Light Source Ltd, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 ODE, England, ^cElectronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China, ^dPhysics Department, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, England, and ^eFEMTO-ST Institute, University of Bourgogne Franche-Comté, CNRS, ENSMM, Time and Frequency Department, 26 rue de l'Epitaphe, 25030 Besançon, France
^*Correspondence e-mail: s.huband@warwick.ac.uk

Edited by N. B. Bolotina, Russian Academy of Sciences, Russia (Received 16 October 2016; accepted 26 March 2017; online 1 June 2017)

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points.

Keywords: lithium niobate tantalate; zero birefringence; metripol.

CCDC references: 1540402; 1540403; 1540404; 1540405; 1540406; 1540407; 1540408; 1540409

1. Introduction

Lithium niobate (LN) and lithium tantalate (LT) have both been used extensively for their optical properties in a range of devices: including optical modulators, Pockels cells, optical parametric oscillators, waveguides etc. LN and LT are isostructural and ferroelectric at room temperature, with space group R3c. Their physical properties, however, differ from one another. For example, at room temperature LN has a negative birefringence and congruent LT is positive. Congruent crystals form with the same composition as the initial materials, which does not occur at the stoichiometric (equal Li and Nb or Ta content) composition for LN or LT. In these materials the congruent compositions are Li-deficient with compositions around 48.45 mol% Li₂O (O'Bryan et al., 1985 ; Kushibiki & Ohashi, 2006 ).

A solid-solution LiNb_1 − xTa_xO₃ (LNT) can be formed across the whole compositional range and allows materials to be produced with properties intermediate between those of LN and LT, such as zero-birefringent crystals when the composition is LiNb_0.06Ta_0.96O₃ (Peterson et al., 1967 ; Shimura, 1977 ; Kondo et al., 1979 ; Wood et al., 2008 ). A better understanding of the physical properties as a function of composition could extend the use of current devices that are based solely on either LN or LT. For example, a patent for an LT-based device has been produced by Glazer et al. (2011 ) to accurately measure temperature in the vicinity of the zero-birefringence point. By changing the composition across the LNT solid solution the birefringence of the crystals can be varied allowing a larger operating range for the temperature sensor. The development of these devices relies on understanding the structural and physical properties across the compositional range.

A number of structural studies have been made on LN and LT, generally using congruent crystals that have been Czochralski grown (Abrahams, Reddy et al., 1966 ; Abrahams, Hamilton et al., 1966 ; Abrahams, Levinstein et al., 1966 ; Abrahams & Bernstein, 1967 ; Abrahams et al., 1967 , 1973 ). The initial measurements of the physical properties varied between samples because they can be made with a range of Li content. LN can be made in the range of 46.4–50 mol% Li₂O and LT in the range 46–50 mol% Li₂O (Carruthers et al., 1971 ; Barns & Carruthers, 1970 ). Both LN and LT undergo a high-temperature phase transition to a paraelectric structure with space group $[R \overline{3}c]$ , with the transition varying from 1310 to 1480 K and 780 to 965 K as the Li content increases to 50 mol% Li₂O for LN and LT, respectively (Bordui et al., 1995 ; Barns & Carruthers, 1970).

Structural models including the Li deficiency for LN were introduced by Lerner et al. (1968 ) and Abrahams & Marsh (1986 ) who suggested Li and Nb vacancies, respectively. The formula for the Li vacancy model is given by [Li_1 − 5yM_y]MO₃, and the Nb vacancy model is given by [Li_1 − 5yM_5y]M_1 − 4yO₃. In the formulae the Li deficiency is given by y and M is the Nb content. In this work M also represents Ta and Nb/Ta mixtures. From these models the corresponding mol% Li₂O required can then be calculated by mol% Li₂O = Li/(Li + M). The correct Li deficiency model has not yet been satisfactorily determined and for this reason the Li content is commonly expressed using the mol% Li₂O that would be required in the initial materials (Li₂O and M₂O₅). This convention will be followed in this work when the Li content of materials is discussed. A set of parameters for rhombohedral perovskite structures such as LN and LT was introduced by Megaw & Darlington (1975 ) to parameterize the structure using the cation positions, octahedral distortion and octahedral tilt. In this system the O atom is held fixed at the first O plane (z = 1/12). The position of the Nb/Ta atom is then given by its displacement (t) along the c-axis from the origin, which is also the centre of the oxygen octahedra. The Li position is given by its displacement (s) from the O plane at z = 1/4 and the O position by the octahedral distortion (d) and tilt (e). In polar space groups, the octahedral distortion (d) is a displacement of the O atom in the xy-plane that allows the size of the upper and lower octahedral faces to differ. The upper face of the octahedra is smaller or larger when the octahedral distortion is positive or negative, respectively. The parameter e is related to the octahedral tilt ω by

$[\tan \omega = 4\sqrt3 e. \eqno(1)]$

The change in these parameters with increasing temperature was calculated for LN by Megaw (1968b ) using the powder X-ray diffraction (XRD) measurements of Abrahams, Levinstein & Reddy (1966); the octahedral tilt decreases with increasing temperature, resulting in an increase in the a lattice parameter. The c lattice parameter initially increases until reaching a maximum and then decreases until the Curie point. The curve in the c lattice parameter is explained by the decrease in the Nb displacement with increasing temperature. In the paraelectric phase, both lattice parameters increase with temperature and the Nb displacement and octahedral distortion disappear; however, the octahedral tilt remains.

The birefringence of Czochralski-grown LNT as a function of composition has been studied by Wood et al. (2008) who showed that the birefringence increases linearly as the Ta concentration is increased and a sample with 94 mol% LT would have zero birefringence at room temperature. The properties of LNT are also dependent on the Li content of the crystals; the change in the Curie point and zero-birefringence point have previously been used as a way to quantify the Li content of LT crystals (Barns & Carruthers, 1970; Bäumer et al., 2003 ). The birefringence of LNT crystals is dependent on both the LN/LT content and the Li content, with an increase in Li or LN content resulting in a decrease in the birefringence. A detailed structural investigation has not been made focusing on the zero-birefringence points of LN, LT or LNT crystals.

LNT thin films on LT substrates were produced using a LiVO₃ (LV) flux-growth technique by Kondo et al. (1979), who also produced a phase diagram showing the super-saturation temperature as a function of both the LNT composition and LV content. Recently crystals of LNT have been grown using this flux-growth technique and compared to those made using Czochralski, top-seeded solution growth (TSSG) and floating zone methods (Bartasyte et al., 2012 ). Crystals grown using these four methods resulted in crystals which were Ta-rich compared with the initial materials and considerable Li loss was observed for crystals grown using the floating zone technique.

Here the structures across the LNT compositional range are reported, whilst also considering the Li content of the samples used. XRD measurements were made on a series of powder samples to determine the change in lattice parameters as a function of LT content and temperature. Using these powders as the starting materials, crystals were grown using a LV flux. XRD was used to calculate the structures and the birefringence was then investigated as a function of temperature with a focus on the zero-birefringence points.

2. Experimental details

Powder LNT samples with a mass of 15 g were prepared by a solid-state reaction between Li₂CO₃ (99.99%), Nb₂O₅ (99.99%) and Ta₂O₅ (99.85%). The starting materials were weighed according to the desired ratios and then ball-milled in isopropanol, placed in a platinum crucible with a lid and sintered for 140 h at 1433 K, following the method used by Bartasyte et al. (2012). The main set of samples were made with compositions (LiNb_1 − xTa_xO₃) of x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1, with a further focused region every 0.01 between 0.9 and 1. Variable-temperature measurements were made on compositions with x = 0.94, 0.96, 0.98, 0.99 and 1, along with high-temperature measurements only on x = 0.92.

Low-temperature X-ray diffraction measurements on the powders were performed using a Bruker D5005 diffractometer equipped with a Cu Kα source and an Oxford Cryosystems Phenix cryostat. Room- and high-temperature XRD measurements were made using a PANalytical MPD diffractometer using Cu Kα₁ radiation and an Anton Paar HTK1200 sample furnace. A reflection spinner stage was used for room-temperature measurements with a sample diameter of 1.6 cm. The measurements made with the Anton Paar HTK1200 were also made in air using a sample holder with a diameter of 1.6 cm. Measurements between 20 and 135° in 2θ were made every 20 K between 40 and 300 K and every 40 K between 300 and 1100 K. All sintered powders were ground using a pestle and mortar prior to the XRD measurements. Long room-temperature measurements were made on all of the main samples along with x = 0.91, 0.93, 0.95 and 0.99 from the focused region.

Crystals of LNT were grown using a LV flux and a three-zone vertical tube furnace. A molar ratio of 10 moles of LV to 1 mole of LiNb_1 − xTa_xO₃ was used for the crystal growth of all compositions. The mixed powders were placed in a platinum crucible and covered with a platinum lid. They were heated at a rate of 180 K h⁻¹ to 1473 K, followed by 20 K h⁻¹ to 1573 K and held for 24 h to homogenize the melted material. This was then cooled at a rate of 1 K h⁻¹ until the super-saturation point of the LiNb_1 − xTa_xO₃ in LV given by the LNT–LV phase diagram (Kondo et al., 1979). Once the temperature was sufficiently below the super-saturation point, the cooling rate was increased to 60 K h⁻¹.

The as-grown orientations of the LNT crystals were measured using a PANalytical X'Pert Pro MRD system, equipped with a 4-bounce hybrid monochromator to provide an intense source of Cu Kα₁ radiation and a PIXcel detector. The chemical composition of the samples was studied using energy-dispersive X-ray analysis (EDX) on a Zeiss Supra 55VP FEG scanning electron microscope with EDAX GENESIS software. Single-crystal X-ray diffraction measurements of the grown crystals were performed using an Oxford diffraction Gemini diffractometer equipped with a Mo Kα source.

The experimental setup for second harmonic generation (SHG) measurements is based on that of Kurtz & Perry (1968 ) and is described fully in Jones & Thomas (2002 ). A Nd-YAG laser with a wavelength of 1064 nm and a modulated frequency of 1 Hz was used. The beam was initially split with a glass slide, with one beam sent to a photodiode and the other directed at a sample held inside a furnace with two holes to allow light to pass through. The SHG signal with a wavelength of 532 nm was measured using a photomultiplier tube (PMT) positioned behind a green filter to ensure only the second-harmonic signal was detected. An oscilloscope was used to measure the pulses from the photodiode and the PMT and a computer running LabVIEW was used to record the data from the oscilloscope and calculate an average signal from 10 pulses.

Birefringence imaging microscopy (BIM; Glazer et al., 1996 ) measurements were made every 1 K, while heating and cooling the crystal at a rate of 60 K h⁻¹ between 300 and 873 K using a Linkam THMS600 hot-stage. In the BIM setup, the measured intensity of the rotating polariser and circular analyser is given by

$[I = (I_0/2)[1+\sin (2\varphi -2\alpha)\sin \delta], \eqno(2)]$

where I₀ is equivalent to the transmitted light intensity, φ is the angle measured anticlockwise between the horizontal axis of the microscope (given by the top and bottom of the CCD array of the detector) and the slow axis of the indicatrix, α is the angle of the polariser from a predetermined zero, and δ is the phase shift of the light given by

$[\delta = \left({2\pi \over \lambda }\right)\Delta nt. \eqno(3)]$

Δn is the observed birefringence, t is the sample thickness and λ is the light wavelength. The BIM measurements were analysed using the Metripol software, which produces false-colour images of |sinδ|, φ and the transmitted intensity. The measured |sin δ| oscillates between 0 and 1, with a peak when $[\delta = (2i + 1)\pi /2]$ and a trough when $[\delta = i\pi]$ , where i is an integer. To determine which trough corresponds to the material being zero-birefringent (i = 0) usually requires separate measurements of the refractive indices, however, this is not required when the variation in the birefringence as a function of wavelength is small. In this case, the zero-birefringence (i = 0) troughs will be at the same temperature at each wavelength. Troughs that occur when δ is π, 2π etc. will not be at the same temperature for different wavelengths, allowing the trough corresponding to zero-birefringence to be determined. It has been shown that the birefringence measured between 589 and 1060 nm is relatively constant in LNT (Shimura, 1977), allowing the zero-birefringence point to be determined with the use of 550, 570, 590 and 600 nm wavelength filters.

3. Results and discussion

3.1. Powder diffraction

Rietveld refinements of the room-temperature XRD measurements were made using TOPAS Academic (Coelho, 2007 ). The powders were phase-pure and the refinement of the LT sample is shown in Fig. 1. The measured lattice parameters and Megaw parameters are given in Table 1 along with those calculated by Megaw & Darlington (1975) using the powder X-ray diffraction and single-crystal neutron diffraction measurements of Abrahams & Bernstein (1967) and Abrahams et al. (1967). The crystal used by Abrahams et al. was Czochralski-grown using a congruent composition, whereas the powder sample in this study was stoichiometric. The lattice parameters of the stoichiometric powder are lower than those of the congruent crystal, consistent with the results of Barns & Carruthers (1970). For all compositions, there are no visible superlattice reflections from the ordering of Nb and Ta atoms.

Table 1
Rietveld refinement results for LNT powders between 70 and 100 mol% LT

Composition (mol% LT)	a = b (Å)	c (Å)	t (Å)	s (Å)	d	Tilt (°)	R_wp	R_p	GOF
LT crystal†	5.15428 (1)	13.78351 (2)	0.20 (1)	0.60 (2)	−0.0026 (1)	22.9 (1)	–	–	–
LiTaO₃	5.1523 (1)	13.7768 (1)	0.198 (4)	0.58 (1)	−0.0029 (3)	22.93 (8)	0.1468	0.0937	1.489
99	5.1525 (1)	13.7774 (2)	0.213 (4)	0.63 (1)	−0.0041 (2)	23.24 (7)	0.1093	0.0750	1.724
95	5.1518 (1)	13.7802 (2)	0.204 (3)	0.62 (1)	−0.0027 (2)	23.27 (6)	0.0949	0.0631	1.640
93	5.1518 (1)	13.7819 (2)	0.200 (3)	0.63 (1)	−0.0027 (2)	23.25 (6)	0.0954	0.0636	1.675
91	5.1521 (1)	13.7833 (2)	0.212 (3)	0.64 (1)	−0.0026 (2)	23.29 (6)	0.0894	0.0602	1.461
90	5.1516 (1)	13.7838 (2)	0.209 (3)	0.66 (1)	−0.0029 (3)	23.16 (6)	0.1068	0.0693	1.472
80	5.1513 (1)	13.7914 (2)	0.216 (3)	0.63 (1)	−0.0030 (3)	23.35 (6)	0.1109	0.0723	1.369
70	5.1505 (1)	13.7985 (2)	0.240 (2)	0.61 (1)	−0.0041 (2)	23.45 (5)	0.0835	0.0595	1.733

†Calculated by Megaw & Darlington (1975

) using X-ray diffraction and single-crystal neutron diffraction measurements (Abrahams & Bernstein, 1967

; Abrahams et al., 1967

Figure 1
Rietveld refinement of the powder XRD measurements on LT.

It was found that LNT samples with less than 70 mol% LT content formed with preferred orientation in the (012) plane. The effect of the preferred orientation on the measured diffraction profiles made the refinement of the atomic positions unreliable. The refined lattice parameters are unaffected by this and are shown in Fig. 2. The a and c lattice parameters both show a deviation from Vegard's law. They have been fitted with a quadratic function containing a bowing parameter (b) to describe the deviation

$[p_{{\rm LNT}x} =xp_{\rm LT} + (1-x)p_{\rm LN} - bx(1-x). \eqno(4)]$

where x is the Ta content in LiNb_1 − xTa_xO₃ and P_LNT, P_LT and P_LN are the lattice parameters of LNT, LT and LN, respectively. The a lattice parameter has a bowing parameter of −0.0036 (8), which agrees with the previously determined value of −0.003 (3) (Bartasyte et al., 2012). The c lattice parameter has a bowing parameter of −0.009 (2), which is less than the previously determined value of −0.016 (3). This difference is likely to be a result of the increased number of samples measured with low-LT content in this study. The change in lattice parameter as a function of composition has also been studied by Bak et al. (2014 ) who showed a similar decrease in the c lattice parameter with increasing Ta content. However, they determined the a lattice parameter changes to be negligibly small. The uncertainties in the Megaw t, s, d and tilt parameters are too high to determine a trend in this compositional range.

Figure 2
The a and c lattice parameters from powder XRD measurements as a function of LT content. Quadratic fits are given by the lines.

The lattice parameters of high Ta-content powders have been investigated using XRD measurements between 40 and 1100 K. The c lattice parameter for LiNb_0.06Ta_0.94O₃ is plotted in Fig. 3(a) along with the a lattice parameter in Fig. 3(b). The variation with temperature of the lattice parameters in LiNb_0.06Ta_0.94O₃ is consistent with the powder XRD measurements of Sugii et al. (1976 ) who studied a range of compositions between 300 and 1273 K using crushed Czochralski grown crystals. The lower temperatures studied here show that the lattice parameters decrease less as the temperature is reduced below 250 K and start to level off.

Figure 3
The (a) c lattice parameter and (b) a lattice parameters as a function of temperature for an LNT94 powder sample. In (b), the black line gives a linear fit to the data, and the residual of this fit is plotted in (c). The data above the Curie point are red and have been fitted with a second-order polynomial in (a) and (c), below the Curie point the points are black and are fitted by a fourth-order polynomial in (a) and (c).

The c lattice parameter increases from 40 to 600 K and then decreases to lower than the initial value at 40 K. It decreases until the discontinuity at the Curie point and then begins increasing in the paraelectric phase. The peak in the c lattice parameter is also evident in all compositions measured by Sugii et al. (1976) and is consistent with the suggestion of Megaw (1968b) that the peak and resultant decrease in the c lattice parameter is a result of the decrease in the Nb/Ta displacement. The measured lattice parameters have been fitted with second- and fourth-order polynomials above and below the Curie point, respectively.

The a lattice parameter as a function of temperature is plotted in Fig. 3(b) and has a non-linear increase with temperature. There is also a discontinuity at the Curie point which can be seen clearly by plotting the residual of a linear fit to the data, as shown in Fig. 3(c). As with the c lattice parameter, second- and fourth-order polynomials have been used to fit the residual above and below the Curie point, respectively. The crossing of the polynomial fits provides a measurement of the Curie point of the powder sample. For the LiNb_0.06Ta_0.94O₃ sample this corresponds to 999 (3) K.

The Curie point as a function of composition for samples with greater than 90 mol% LT is plotted in Fig. 4. In this small compositional range the Curie point increases linearly as the Ta concentration is decreased, in agreement with the trend determined by Peterson et al. (1970 ). The LT sample has a Curie point at 966 (3) K, which agrees with the value of 963 K determined on a stoichiometric crystal by Barns & Carruthers (1970).

Figure 4
The Curie point of Ta-rich LNT powders as a function of LT content.

3.2. LNT crystal measurements

The crystals grown using the flux-growth technique were predominantly plate-like with a few cuboidal crystals. Many of the crystals were visibly twinned and contained flux inclusions. Following each growth, the best-quality crystal was selected and prepared for further measurements. The crystals were polished such that the largest as-grown face became one surface of a crystal plate between 200 and 300 µm thick. For the congruent crystal measurements, a Z-cut plate of LT purchased from MTI Corporation (a supplier of crystal substrates) was used.

The normalized SHG signal for the LNT100 crystal, grown by the LV flux method, is plotted during heating and cooling in Fig. 5. The measured signal is lower on cooling than on heating and both drop to a background level at the Curie point. This was judged visually along with the uncertainties giving a Curie point of 940 (4) K. The Curie point of the congruent LT crystal is 873 (4) K and closely agrees with the value of 876.0 K precisely determined by Kushibiki & Ohashi (2006). The Li content of the LT sample is 49.65 (10) mol% Li₂O according to the relationship between Curie temperature and composition given by Bordui et al. (1995). This gives the formula Li_0.98675(Nb_1 − xTa_x)_1.00265O_3. This composition is between the congruent and stoichiometric values of 48.6 and 50 mol% Li₂O, respectively. There is likely to be some variation in the Li content of the crystals at different LN/LT compositions, but it is expected to remain between the congruent and stoichiometric values. It was shown for LT by Barns & Carruthers (1970) that a decrease in Li content would cause an increase in the a and c lattice parameters.

Figure 5
The normalized SHG signal during heating and cooling of a flux-grown LT crystal and inset is a 2θ XRD scan, showing the 012, 024 and 036 reflections.

The planes corresponding to the large surfaces of all of the LNT flux grown plates are the (012) planes, as shown by the out-of-plane XRD measurements inset in Fig. 5. These scans include three peaks corresponding to the 012, 024 and 036 reflections. This is consistent with the preferred orientation of the powder LNT samples, also, these planes are the twin planes and dominant cleavage planes in LN and LT.

The composition of the grown crystals has been determined using EDX and is in agreement with the results of Bartasyte et al. (2012) that the crystals are Ta-rich compared with the initial materials. The determined compositions are listed in Table 2 and the uncertainties were estimated from the variation in the values measured across the samples. There was no evidence from the EDX of V contamination within the crystals, however, the crystals had a yellow/green coloration. LN and LT crystals are clear, which suggests there could be some V contamination, which is below the detection limits of EDX.

Table 2
Refined structural parameters of flux-grown LNT crystals using XRD measurements

Composition (mol% LT)	a = b (Å)	c (Å)	t (Å)	s (Å)	d	Tilt (°)	R_obs
LT crystal†	5.15428 (1)	13.78351 (2)	0.20 (1)	0.60 (2)	−0.0026 (1)	22.9 (1)	–
LT	5.148 (1)	13.767 (5)	0.208 (8)	0.62 (6)	−0.0027 (2)	22.9 (1)	0.0165
92 (3)	5.149 (1)	13.781 (5)	0.207 (7)	0.66 (4)	−0.0028 (2)	22.9 (1)	0.0190
89 (3)	5.151 (1)	13.776 (5)	0.203 (7)	0.62 (7)	−0.0026 (2)	22.9 (1)	0.0169
64 (3)	5.149 (1)	13.786 (5)	0.222 (6)	0.68 (4)	−0.0022 (2)	23.0 (1)	0.0155
60 (3)	5.147 (1)	13.798 (5)	0.216 (6)	0.65 (3)	−0.0024 (2)	23.0 (1)	0.0144
53 (3)	5.147 (1)	13.834 (5)	0.237 (8)	0.66 (6)	−0.0024 (2)	23.1 (1)	0.0235
30 (3)	5.145 (1)	13.841 (5)	0.255 (6)	0.64 (4)	−0.0025 (2)	23.2 (1)	0.0246
LN	5.146 (1)	13.859 (5)	0.276 (4)	0.69 (3)	−0.0025 (2)	23.24 (5)	0.0210
LN crystal†	5.14829 (2)	13.8631 (4)	0.28 (1)	0.70 (2)	−0.0025 (2)	23.3 (1)	–

†Calculated using X-ray and neutron diffraction measurements (Abrahams & Bernstein, 1967

; Abrahams et al., 1967

; Abrahams, Reddy et al., 1966

; Abrahams, Hamilton et al., 1966

The collected diffraction data were indexed and integrated using the CrysAlisPro software and the absorption corrected with the analytical method of Clark & Reid (1995 ). The corrected intensities were analysed using SHELX and the refined structures from the powder diffraction measurements were used as a starting point. Initial refinements were made allowing the Nb and Ta occupancies to vary, but these were not in agreement with the values determined by EDX and varied inconsistently as a function of composition. Following this, the refinements were made with fixed Nb and Ta occupancies similar to the Rietveld refinements. Attempts were also made to refine the data using the Li-deficiency models but these were also unsuccessful, so the refinements were made with the occupancies fixed at their stoichiometric values.

Structural refinements using SHELX gave R_obs values between 0.014 and 0.025, with anisotropic displacement parameters (Sheldrick, 2008 ). The a and c lattice parameters are plotted as a function of the measured composition of the crystals in Fig. 6, along with the results of the powder diffraction measurements. For the c lattice parameter, the measurements on powders and single crystals agree with each other. The a lattice parameter values from single crystals are less than those from powder measurements. This could be the result of a small amount of V incorporation within the crystals, which is below the detection limits of the EDX measurements.

Figure 6
The (a) a lattice parameters and (b) c lattice parameters of single-crystal LV flux-grown LNT crystals as a function of composition. The lines are the quadratic fits to the powder samples in Fig. 2

The refined Megaw parameters for the LNT single crystals are included in Table 2, along with the previous values determined for LN and LT (Abrahams, Reddy et al., 1966; Abrahams, Hamilton et al., 1966; Abrahams & Bernstein, 1967; Abrahams et al., 1967). The values determined using LV flux-grown crystals agree with those determined previously on LN and LT crystals.

The refined Megaw parameters of the LNT crystals are plotted in Fig. 7. The Nb/Ta displacement increases linearly as the Ta concentration is decreased. A trend in the Li displacement cannot be determined because of the uncertainties on the refined values. However, for all LNT compositions, the Li displacement is between 0.62 and 0.7 Å, which is consistent with values determined for LN and LT using neutron diffraction (Abrahams, Hamilton et al., 1966; Abrahams et al., 1967). The trend in the octahedral distortion also cannot be determined because of the measurement uncertainties, but it can be seen that the values are small and negative as expected from the previous measurements. The higher uncertainties in the Li and O position compared with those of Nb and Ta are expected because of their lower atomic scattering factors. However, despite the larger uncertainties for the position of the O atom, a trend showing an increase in the octahedral tilt with increasing LN content can be determined. The lack of scatter around the linear fits of the Nb/Ta displacement and octahedral tilt suggests a similar Li deficiency across the compositional range. The Li and O positions can be determined precisely using neutron diffraction, which has been done for LT as a function of temperature showing the Li displacement decreases with increasing temperature (Huband et al., 2017 ).

Figure 7
The (a) Nb/Ta displacement, (b) Li displacement, (c) octahedral distortion and (d) octahedral tilt of LV flux-grown LNT single crystals as a function of LT content, given by the black squares. The results previously calculated from X-ray and neutron diffraction measurements are given by the red circles (Abrahams & Bernstein, 1967

; Abrahams et al., 1967

; Abrahams, Reddy et al., 1966

; Abrahams, Hamilton et al., 1966

It was shown by Megaw that the Nb displacement and octahedral tilt decrease with increasing temperature (Megaw, 1968a ,b). This is similar to the change in these parameters as a function of composition; the decrease in the Ta content results in an increase in both the Nb/Ta displacement and the octahedral tilt. The increase in the Nb/Ta displacement also results in an increase in the c lattice parameter, whereas the increase in the octahedral tilt angle results in a decrease in the a lattice parameter.

Heating and cooling runs were made using the Metripol system at 550, 570, 590 and 600 nm. The measured |sin δ| images of the LNT crystals were analysed by averaging the values measured in a 12 × 12 pixel square, sufficiently away from any scratches on the sample. The sample movement was accounted for to ensure the same sample area was analysed at each temperature. The measured |sin δ| at 550 nm as a function of temperature for the LiNb_0.34Ta_0.64O₃ crystal is plotted in Fig. 8(a) during heating. Theoretically, the |sin δ| signal should oscillate between 0 and 1; however, this only occurs at the zero-birefringence point and the amplitude of the oscillations decreases above and below this. A similar effect has been measured in LT, LNT and other crystals that contain very small domains, which tend to scatter the light (Glazer et al., 2010 ). The maximum operating temperature of the furnace is 873 K, limiting the range of composition that can be analysed with this technique.

Figure 8
The measured |sin δ| of the flux-grown LiNb_0.34Ta_0.64O₃ crystal while heating using (a) 550 nm and (b) 550, 570, 590 and 600 nm wavelength filters. The zero-birefringence temperature is given by the dashed vertical red line.

The measured |sin δ| for each wavelength is shown in Fig. 8(b) for LiNb_0.34Ta_0.64O₃. The trough corresponding to zero-birefringence is marked by the dashed vertical red line. Above and below this the troughs in each wavelength diverge allowing the zero-birefringence temperature to be determined. For the LV flux-grown crystals the measured zero-birefringence temperature increases linearly as the Ta concentration is decreased, shown in Fig. 9. This trend is consistent with the measurements of Wood et al. (2008) on congruent LNT crystals. The zero-birefringence value for the LT crystal is higher than the values measured on congruent samples, confirming that these crystals have a higher Li-content (Bäumer et al., 2003). Using the comparison between Li content and zero-birefringence temperature produced by Bäumer et al. (2003) gives a Li content of 49.6 (1) mol% Li₂O, which is in close agreement with the composition determined using the Curie point.

Figure 9
Zero-birefringence temperature of LNT crystals as a function of LT content.

4. Conclusions

The Li content of a LV flux-grown LT crystal was calculated to be 49.65 (10) and 49.6 (1) mol% Li₂O using measurements of the Curie point and zero-birefringence temperature, respectively. The zero-birefringent temperature determined using flux-grown crystals increases as the LT content decreases, with a zero-birefringence temperature between 300 and 400 K for crystals with greater than 90 mol% LT. XRD and SHG measurements do not show any changes through these zero-birefringence points, confirming that the material remains polar at this temperature. At higher temperatures, the lattice parameters determined using high-resolution powder XRD measurements can be used to determine the transition temperature to the paraelectric phase.

Along with the zero-birefringence temperature, the c lattice parameter, Nb/Ta displacement and octahedral tilt angle also increase as the LT content is decreased. This compositional variation is similar to the thermal behaviour in LN as the temperature is increased; the c lattice parameter, Nb displacement and octahedral tilt decrease, whereas the birefringence increases (Megaw, 1968b). This suggests the birefringence correlates with the structural changes; increases in the c lattice parameter, Nb/Ta displacement and octahedral tilt cause a decrease in the birefringence and result in a higher zero-birefringence temperature as the LT content is reduced.

These results also show that zero-birefringence in materials in which the birefringence has a small dependence on wavelength can be determined by repeated measurements using different wavelengths. This reduces the need to use compensation methods or more complicated methods to determine the order of the birefringence.

Supporting information

CCDC references: 1540402; 1540403; 1540404; 1540405; 1540406; 1540407; 1540408; 1540409

Crystal structure: contains datablocks LNT0, LNT30, LNT53, LNT60, LNT64, LNT89, LNT92, LNT100. DOI: https://doi.org/10.1107/S2052520617004711/bp5094sup1.cif

Structure factors: contains datablock LNT0. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT0sup2.hkl

Structure factors: contains datablock LNT30. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT30sup3.hkl

Structure factors: contains datablock LNT53. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT53sup4.hkl

Structure factors: contains datablock LNT60. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT60sup5.hkl

Structure factors: contains datablock LNT64. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT64sup6.hkl

Structure factors: contains datablock LNT89. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT89sup7.hkl

Structure factors: contains datablock LNT92. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT92sup8.hkl

Structure factors: contains datablock LNT100. DOI: https://doi.org/10.1107/S2052520617004711/bp5094LNT100sup9.hkl

Computing details top

Data collection: CrysAlis PRO 1.171.38.43d (Rigaku OD, 2015) for LNT0, LNT30, LNT53; CrysAlis PRO, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) for LNT60, LNT64, LNT89, LNT92, LNT100. Cell refinement: CrysAlis PRO 1.171.38.43d (Rigaku OD, 2015) for LNT0, LNT30, LNT53; CrysAlis PRO, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) for LNT60, LNT64, LNT89, LNT92, LNT100. Data reduction: CrysAlis PRO 1.171.38.43d (Rigaku OD, 2015) for LNT0, LNT30, LNT53; CrysAlis PRO, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) for LNT60, LNT64, LNT89, LNT92, LNT100. Program(s) used to solve structure: SIR2004 (Burla et al., 2007) for LNT53. For all structures, program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: Olex2 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 (Dolomanov et al., 2009).

lithium niobate (LNT0) top

Crystal data top

LiNbO₃	D_x = 4.635 Mg m⁻³
M_r = 147.85	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 3603 reflections
a = 5.146 (1) Å	θ = 4.4–37.3°
c = 13.859 (5) Å	µ = 5.34 mm⁻¹
V = 317.84 (17) Å³	T = 293 K
Z = 6	Block, clear green
F(000) = 408	0.27 × 0.24 × 0.22 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	378 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	375 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.055
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.6°, θ_min = 5.4°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro 1.171.38.43d (Rigaku Oxford Diffraction, 2015) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.333, T_max = 0.432	l = −23→23
3994 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0358P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.021	(Δ/σ)_max < 0.001
wR(F²) = 0.048	Δρ_max = 0.43 e Å⁻³
S = 1.14	Δρ_min = −1.13 e Å⁻³
378 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
17 parameters	Extinction coefficient: 0.251 (13)
1 restraint	Absolute structure: Classical Flack method preferred over Parsons because s.u. lower.
Primary atom site location: Other	Absolute structure parameter: −0.2 (3)

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Nb01	0.0000	0.0000	0.9677 (3)	0.00458 (17)
O002	0.9523 (2)	0.6567 (2)	0.9043 (3)	0.0071 (3)
Li01	0.0000	0.0000	0.688 (2)	0.014 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Nb01	0.00481 (19)	0.00481 (19)	0.0041 (2)	0.00240 (10)	0.000	0.000
O002	0.0076 (6)	0.0062 (4)	0.0073 (4)	0.0032 (5)	−0.0013 (5)	−0.0019 (2)
Li01	0.012 (5)	0.012 (5)	0.018 (7)	0.006 (2)	0.000	0.000

Geometric parameters (Å, º) top

Nb01—O002ⁱ	1.876 (2)	O002—Li01^vii	2.26 (2)
Nb01—O002ⁱⁱ	2.129 (3)	O002—Li01^xiv	2.053 (10)
Nb01—O002ⁱⁱⁱ	2.129 (3)	Li01—Nb01^xv	3.06 (3)
Nb01—O002^iv	1.876 (2)	Li01—Nb01^xvi	3.064 (7)
Nb01—O002^v	1.876 (2)	Li01—Nb01^xiii	3.357 (14)
Nb01—O002^vi	2.129 (3)	Li01—Nb01^xvii	3.064 (7)
Nb01—Li01^vii	3.064 (7)	Li01—Nb01^xviii	3.357 (14)
Nb01—Li01^viii	3.06 (3)	Li01—Nb01^xix	3.064 (7)
Nb01—Li01^ix	3.064 (7)	Li01—O002^xx	2.053 (10)
Nb01—Li01^x	3.064 (7)	Li01—O002^xxi	2.26 (2)
Nb01—Li01^xi	3.357 (14)	Li01—O002^xxii	2.053 (10)
Nb01—Li01ⁱⁱⁱ	3.357 (14)	Li01—O002^xxiii	2.26 (2)
O002—Nb01^xii	1.876 (2)	Li01—O002^xvi	2.26 (2)
O002—Nb01^xiii	2.129 (3)	Li01—O002^xxiv	2.053 (10)

O002ⁱ—Nb01—O002^v	99.85 (16)	Nb01^xiii—O002—Li01^vii	88.1 (5)
O002^v—Nb01—O002ⁱⁱ	88.60 (4)	Li01^xiv—O002—Nb01^xiii	94.2 (6)
O002ⁱ—Nb01—O002ⁱⁱⁱ	88.60 (4)	Li01^xiv—O002—Li01^vii	121.2 (6)
O002ⁱⁱ—Nb01—O002ⁱⁱⁱ	79.75 (15)	Nb01^xvi—Li01—Nb01^xiii	166.4 (10)
O002^iv—Nb01—O002ⁱⁱ	90.01 (5)	Nb01^xvi—Li01—Nb01^xviii	71.60 (11)
O002ⁱⁱ—Nb01—O002^vi	79.75 (15)	Nb01^xix—Li01—Nb01^xiii	71.60 (11)
O002ⁱ—Nb01—O002^iv	99.85 (16)	Nb01^xv—Li01—Nb01^xvii	75.9 (5)
O002^iv—Nb01—O002ⁱⁱⁱ	165.6 (2)	Nb01^xvii—Li01—Nb01^xix	114.2 (4)
O002ⁱ—Nb01—O002^vi	90.01 (4)	Nb01^xv—Li01—Nb01^xix	75.9 (5)
O002^v—Nb01—O002^vi	165.6 (2)	Nb01^xix—Li01—Nb01^xviii	71.60 (11)
O002^v—Nb01—O002^iv	99.85 (16)	Nb01^xvi—Li01—Nb01^xvii	114.3 (4)
O002^iv—Nb01—O002^vi	88.60 (4)	Nb01^xvii—Li01—Nb01^xiii	71.60 (11)
O002^v—Nb01—O002ⁱⁱⁱ	90.02 (4)	Nb01^xiii—Li01—Nb01^xviii	100.1 (6)
O002ⁱ—Nb01—O002ⁱⁱ	165.6 (2)	Nb01^xv—Li01—Nb01^xvi	75.9 (5)
O002ⁱⁱⁱ—Nb01—O002^vi	79.75 (15)	Nb01^xvi—Li01—Nb01^xix	114.2 (4)
O002ⁱ—Nb01—Li01^viii	117.93 (13)	Nb01^xvii—Li01—Nb01^xviii	166.4 (10)
O002ⁱⁱⁱ—Nb01—Li01ⁱⁱⁱ	147.4 (3)	Nb01^xv—Li01—Nb01^xviii	117.7 (4)
O002ⁱⁱⁱ—Nb01—Li01^xi	73.4 (4)	Nb01^xv—Li01—Nb01^xiii	117.7 (4)
O002^v—Nb01—Li01^viii	117.93 (13)	O002^xxiv—Li01—Nb01^xvii	43.86 (19)
O002^iv—Nb01—Li01^xi	120.3 (4)	O002^xxiii—Li01—Nb01^xix	111.7 (9)
O002ⁱ—Nb01—Li01^ix	47.4 (5)	O002^xxii—Li01—Nb01^xix	95.87 (4)
O002^v—Nb01—Li01^vii	142.7 (3)	O002^xxii—Li01—Nb01^xv	109.5 (8)
O002ⁱ—Nb01—Li01^x	142.7 (3)	O002^xxiii—Li01—Nb01^xv	44.1 (5)
O002ⁱ—Nb01—Li01^xi	71.44 (19)	O002^xvi—Li01—Nb01^xvi	111.7 (9)
O002ⁱⁱⁱ—Nb01—Li01^vii	119.5 (5)	O002^xx—Li01—Nb01^xix	43.86 (19)
O002^vi—Nb01—Li01^viii	47.75 (10)	O002^xxiii—Li01—Nb01^xvii	84.1 (5)
O002^iv—Nb01—Li01^x	103.0 (2)	O002^xxiv—Li01—Nb01^xviii	125.2 (10)
O002ⁱ—Nb01—Li01^vii	103.0 (2)	O002^xxi—Li01—Nb01^xiii	105.58 (11)
O002^iv—Nb01—Li01^ix	142.7 (3)	O002^xvi—Li01—Nb01^xviii	153.8 (6)
O002ⁱⁱⁱ—Nb01—Li01^x	76.1 (4)	O002^xx—Li01—Nb01^xv	109.5 (8)
O002ⁱⁱ—Nb01—Li01^ix	119.5 (5)	O002^xxi—Li01—Nb01^xvi	84.1 (5)
O002^vi—Nb01—Li01^ix	76.1 (4)	O002^xxiii—Li01—Nb01^xviii	105.58 (11)
O002^iv—Nb01—Li01ⁱⁱⁱ	32.92 (8)	O002^xxii—Li01—Nb01^xvii	149.6 (2)
O002^iv—Nb01—Li01^vii	47.4 (5)	O002^xxi—Li01—Nb01^xvii	111.7 (9)
O002^v—Nb01—Li01^xi	32.92 (9)	O002^xxiii—Li01—Nb01^xiii	153.8 (6)
O002^v—Nb01—Li01^ix	103.0 (2)	O002^xvi—Li01—Nb01^xix	84.1 (5)
O002ⁱⁱ—Nb01—Li01^xi	112.5 (3)	O002^xvi—Li01—Nb01^xiii	80.61 (8)
O002^v—Nb01—Li01^x	47.4 (5)	O002^xxi—Li01—Nb01^xix	37.60 (11)
O002^vi—Nb01—Li01^xi	147.4 (3)	O002^xxiv—Li01—Nb01^xix	149.6 (2)
O002^vi—Nb01—Li01^vii	41.9 (4)	O002^xvi—Li01—Nb01^xv	44.1 (5)
O002^v—Nb01—Li01ⁱⁱⁱ	71.44 (19)	O002^xx—Li01—Nb01^xviii	80.0 (5)
O002^iv—Nb01—Li01^viii	117.93 (13)	O002^xxi—Li01—Nb01^xv	44.1 (5)
O002ⁱⁱ—Nb01—Li01ⁱⁱⁱ	73.4 (4)	O002^xx—Li01—Nb01^xvi	149.6 (2)
O002ⁱ—Nb01—Li01ⁱⁱⁱ	120.3 (4)	O002^xxii—Li01—Nb01^xvi	43.86 (19)
O002^vi—Nb01—Li01ⁱⁱⁱ	112.5 (3)	O002^xxiv—Li01—Nb01^xvi	95.87 (4)
O002ⁱⁱ—Nb01—Li01^viii	47.75 (10)	O002^xxii—Li01—Nb01^xiii	125.2 (10)
O002ⁱⁱⁱ—Nb01—Li01^ix	41.9 (4)	O002^xxiii—Li01—Nb01^xvi	37.60 (11)
O002ⁱⁱ—Nb01—Li01^vii	76.1 (4)	O002^xx—Li01—Nb01^xiii	29.8 (2)
O002ⁱⁱ—Nb01—Li01^x	41.9 (4)	O002^xxi—Li01—Nb01^xviii	80.61 (8)
O002ⁱⁱⁱ—Nb01—Li01^viii	47.75 (10)	O002^xvi—Li01—Nb01^xvii	37.60 (11)
O002^vi—Nb01—Li01^x	119.5 (5)	O002^xxii—Li01—Nb01^xviii	29.8 (2)
Li01^vii—Nb01—Li01^xi	166.4 (10)	O002^xx—Li01—Nb01^xvii	95.87 (4)
Li01^vii—Nb01—Li01ⁱⁱⁱ	71.60 (11)	O002^xxiv—Li01—Nb01^xv	109.5 (8)
Li01^vii—Nb01—Li01^x	114.2 (4)	O002^xxiv—Li01—Nb01^xiii	80.0 (5)
Li01^viii—Nb01—Li01^vii	75.9 (5)	O002^xxii—Li01—O002^xvi	152.8 (13)
Li01^x—Nb01—Li01^xi	71.60 (11)	O002^xxii—Li01—O002^xxi	89.3 (3)
Li01^viii—Nb01—Li01^x	75.9 (5)	O002^xxiv—Li01—O002^xxi	152.8 (13)
Li01^ix—Nb01—Li01^xi	71.60 (11)	O002^xxii—Li01—O002^xx	109.5 (8)
Li01^ix—Nb01—Li01^x	114.2 (4)	O002^xx—Li01—O002^xxi	80.8 (3)
Li01^viii—Nb01—Li01^xi	117.7 (4)	O002^xx—Li01—O002^xxiii	152.8 (13)
Li01^vii—Nb01—Li01^ix	114.3 (4)	O002^xxiii—Li01—O002^xvi	74.1 (8)
Li01^viii—Nb01—Li01^ix	75.9 (5)	O002^xvi—Li01—O002^xxi	74.1 (8)
Li01^x—Nb01—Li01ⁱⁱⁱ	71.60 (11)	O002^xxii—Li01—O002^xxiv	109.5 (8)
Li01^viii—Nb01—Li01ⁱⁱⁱ	117.7 (5)	O002^xx—Li01—O002^xxiv	109.5 (8)
Li01^xi—Nb01—Li01ⁱⁱⁱ	100.1 (6)	O002^xxiv—Li01—O002^xvi	80.8 (3)
Li01^ix—Nb01—Li01ⁱⁱⁱ	166.4 (10)	O002^xxii—Li01—O002^xxiii	80.8 (3)
Nb01^xii—O002—Nb01^xiii	139.91 (9)	O002^xxiv—Li01—O002^xxiii	89.3 (3)
Nb01^xii—O002—Li01^xiv	117.3 (3)	O002^xxiii—Li01—O002^xxi	74.1 (8)
Nb01^xii—O002—Li01^vii	95.0 (4)	O002^xx—Li01—O002^xvi	89.3 (3)

Symmetry codes: (i) x−1, y−1, z; (ii) −x+y+1/3, y−1/3, z+1/6; (iii) −y+1/3, −x+2/3, z+1/6; (iv) −y+1, x−y, z; (v) −x+y, −x+1, z; (vi) x−2/3, x−y−1/3, z+1/6; (vii) x+2/3, y+1/3, z+1/3; (viii) −y, −x, z+1/2; (ix) x−1/3, y−2/3, z+1/3; (x) x−1/3, y+1/3, z+1/3; (xi) −y−2/3, −x−1/3, z+1/6; (xii) x+1, y+1, z; (xiii) −y+2/3, −x+1/3, z−1/6; (xiv) −y+4/3, −x+2/3, z+1/6; (xv) −y, −x, z−1/2; (xvi) x−2/3, y−1/3, z−1/3; (xvii) x+1/3, y+2/3, z−1/3; (xviii) −y−1/3, −x−2/3, z−1/6; (xix) x+1/3, y−1/3, z−1/3; (xx) −x+y+2/3, y−2/3, z−1/6; (xxi) −x+y+1/3, −x+2/3, z−1/3; (xxii) x−4/3, x−y−2/3, z−1/6; (xxiii) −y+1/3, x−y−1/3, z−1/3; (xxiv) −y+2/3, −x+4/3, z−1/6.

lithium niobate tantalate (LNT30) top

Crystal data top

LiNb_0.70O₃Ta_0.30	D_x = 5.472 Mg m⁻³
M_r = 174.26	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 3520 reflections
a = 5.145 (1) Å	θ = 4.4–37.2°
c = 13.841 (5) Å	µ = 19.23 mm⁻¹
V = 317.30 (17) Å³	T = 293 K
Z = 6	Block, clear green
F(000) = 466	0.26 × 0.20 × 0.19 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	375 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	367 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.057
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.4°, θ_min = 5.4°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro 1.171.38.43d (Rigaku Oxford Diffraction, 2015) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.038, T_max = 0.136	l = −23→23
3965 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0415P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.025	(Δ/σ)_max < 0.001
wR(F²) = 0.061	Δρ_max = 1.71 e Å⁻³
S = 1.21	Δρ_min = −1.54 e Å⁻³
375 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
17 parameters	Extinction coefficient: 0.113 (8)
1 restraint	Absolute structure: Flack x determined using 178 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
Primary atom site location: Other	Absolute structure parameter: 0.05 (8)

Special details top

Refinement. n

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ta	0.0000	0.0000	0.0034 (4)	0.0081 (2)	0.3
Nb	0.0000	0.0000	0.0034 (4)	0.0081 (2)	0.7
O	0.0481 (3)	0.3433 (4)	0.0683 (4)	0.0074 (4)
Li	0.0000	0.0000	0.281 (3)	0.011 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.0083 (3)	0.0083 (3)	0.0078 (3)	0.00415 (13)	0.000	0.000
Nb	0.0083 (3)	0.0083 (3)	0.0078 (3)	0.00415 (13)	0.000	0.000
O	0.0077 (9)	0.0065 (6)	0.0077 (6)	0.0034 (8)	−0.0009 (8)	−0.0017 (4)
Li	0.009 (6)	0.009 (6)	0.014 (9)	0.005 (3)	0.000	0.000

Geometric parameters (Å, º) top

Ta—O	1.885 (3)	O—Li^viii	2.30 (3)
Ta—Oⁱ	2.113 (4)	O—Li^xii	2.038 (11)
Ta—Oⁱⁱ	2.113 (4)	Li—Ta^xiii	3.070 (9)
Ta—Oⁱⁱⁱ	1.885 (3)	Li—Ta^xiv	3.070 (9)
Ta—O^iv	1.885 (3)	Li—Ta^xv	3.070 (9)
Ta—O^v	2.113 (4)	Li—Nb^xiv	3.070 (9)
Ta—Li^vi	3.070 (9)	Li—Nb^xiii	3.070 (9)
Ta—Liⁱ	3.342 (16)	Li—Nb^xv	3.070 (9)
Ta—Li^vii	3.08 (4)	Li—O^xvi	2.038 (11)
Ta—Li^viii	3.070 (9)	Li—O^xvii	2.038 (11)
Ta—Li^ix	3.342 (16)	Li—O^xviii	2.30 (3)
Ta—Li^x	3.070 (9)	Li—O^xix	2.038 (11)
O—Ta^xi	2.113 (4)	Li—O^xx	2.30 (3)
O—Nb^xi	2.113 (4)	Li—O^xiv	2.30 (3)

O—Ta—Oⁱⁱⁱ	99.2 (2)	Ta—O—Li^viii	93.9 (5)
O^iv—Ta—Oⁱ	166.6 (3)	Nb^xi—O—Li^viii	88.6 (6)
O^iv—Ta—O^v	88.74 (6)	Li^xii—O—Ta^xi	95.4 (7)
O—Ta—O^iv	99.2 (2)	Li^xii—O—Nb^xi	95.4 (7)
O—Ta—O^v	90.15 (6)	Li^xii—O—Li^viii	120.2 (7)
Oⁱⁱⁱ—Ta—O^iv	99.2 (2)	Ta^xiii—Li—Ta^xiv	113.8 (5)
Oⁱⁱⁱ—Ta—Oⁱ	90.15 (6)	Ta^xiii—Li—Ta^xv	113.8 (5)
O—Ta—Oⁱⁱ	166.6 (3)	Ta^xiv—Li—Ta^xv	113.8 (5)
Oⁱⁱ—Ta—Oⁱ	80.4 (2)	Ta^xiv—Li—Nb^xv	113.8 (5)
Oⁱⁱⁱ—Ta—Oⁱⁱ	88.74 (6)	Ta^xiii—Li—Nb^xiii	0.0 (2)
Oⁱⁱⁱ—Ta—O^v	166.6 (3)	Ta^xiii—Li—Nb^xv	113.8 (5)
O^iv—Ta—Oⁱⁱ	90.15 (6)	Ta^xv—Li—Nb^xv	0.0 (2)
Oⁱⁱ—Ta—O^v	80.4 (2)	Ta^xiv—Li—Nb^xiv	0.0
O—Ta—Oⁱ	88.73 (6)	Ta^xiii—Li—Nb^xiv	113.8 (5)
Oⁱ—Ta—O^v	80.4 (2)	Nb^xiii—Li—Ta^xiv	113.8
Oⁱⁱ—Ta—Li^x	41.4 (5)	Nb^xiv—Li—Ta^xv	113.8
O^iv—Ta—Li^ix	32.98 (12)	Nb^xiii—Li—Ta^xv	113.8
O—Ta—Li^x	142.7 (3)	Nb^xiv—Li—Nb^xv	113.8 (5)
O^v—Ta—Li^x	119.4 (6)	Nb^xiii—Li—Nb^xv	113.8 (5)
Oⁱ—Ta—Li^viii	41.4 (5)	Nb^xiii—Li—Nb^xiv	113.8 (5)
O^iv—Ta—Li^vii	118.47 (17)	O^xx—Li—Ta^xiv	83.5 (6)
O^iv—Ta—Li^x	103.3 (3)	O^xviii—Li—Ta^xv	37.76 (14)
Oⁱ—Ta—Li^vii	48.19 (13)	O^xx—Li—Ta^xv	110.6 (10)
Oⁱ—Ta—Li^ix	147.2 (3)	O^xiv—Li—Ta^xiii	110.6 (10)
O—Ta—Liⁱ	71.4 (2)	O^xvii—Li—Ta^xiv	149.79 (16)
O^v—Ta—Li^viii	75.8 (4)	O^xvii—Li—Ta^xiii	43.2 (2)
O^iv—Ta—Liⁱ	120.2 (5)	O^xiv—Li—Ta^xv	83.5 (6)
Oⁱⁱⁱ—Ta—Li^x	48.3 (6)	O^xviii—Li—Ta^xiv	110.6 (10)
Oⁱ—Ta—Liⁱ	72.5 (5)	O^xvi—Li—Ta^xiv	43.2 (2)
O—Ta—Li^ix	120.2 (5)	O^xvi—Li—Ta^xiii	95.72 (7)
Oⁱ—Ta—Li^x	75.8 (4)	O^xviii—Li—Ta^xiii	83.5 (6)
O—Ta—Li^vi	103.3 (3)	O^xx—Li—Ta^xiii	37.76 (14)
Oⁱⁱⁱ—Ta—Li^vii	118.47 (17)	O^xix—Li—Ta^xiii	149.79 (16)
Oⁱⁱⁱ—Ta—Li^vi	142.7 (3)	O^xix—Li—Ta^xv	43.2 (2)
Oⁱⁱ—Ta—Li^vii	48.19 (13)	O^xix—Li—Ta^xiv	95.72 (7)
O^iv—Ta—Li^vi	48.3 (6)	O^xvii—Li—Ta^xv	95.72 (7)
O^v—Ta—Li^vii	48.19 (13)	O^xvi—Li—Ta^xv	149.79 (16)
Oⁱⁱ—Ta—Li^vi	75.7 (4)	O^xiv—Li—Ta^xiv	37.76 (14)
Oⁱⁱⁱ—Ta—Liⁱ	32.98 (12)	O^xix—Li—Nb^xiv	95.72 (7)
Oⁱ—Ta—Li^vi	119.4 (6)	O^xviii—Li—Nb^xv	37.76 (14)
Oⁱⁱ—Ta—Liⁱ	112.1 (3)	O^xvii—Li—Nb^xv	95.72 (7)
O^v—Ta—Li^vi	41.4 (5)	O^xvii—Li—Nb^xiv	149.79 (16)
O^v—Ta—Liⁱ	147.2 (3)	O^xviii—Li—Nb^xiii	83.5 (6)
O—Ta—Li^viii	48.3 (6)	O^xvi—Li—Nb^xiv	43.2 (2)
Oⁱⁱⁱ—Ta—Li^ix	71.4 (2)	O^xx—Li—Nb^xv	110.6 (10)
Oⁱⁱⁱ—Ta—Li^viii	103.3 (3)	O^xx—Li—Nb^xiv	83.5 (6)
Oⁱⁱ—Ta—Li^ix	72.5 (5)	O^xiv—Li—Nb^xiii	110.6 (10)
O^iv—Ta—Li^viii	142.7 (3)	O^xiv—Li—Nb^xiv	37.76 (14)
O^v—Ta—Li^ix	112.1 (3)	O^xix—Li—Nb^xv	43.2 (2)
Oⁱⁱ—Ta—Li^viii	119.4 (6)	O^xviii—Li—Nb^xiv	110.6 (10)
O—Ta—Li^vii	118.47 (17)	O^xvi—Li—Nb^xv	149.79 (16)
Li^vi—Ta—Liⁱ	167.4 (12)	O^xix—Li—Nb^xiii	149.79 (16)
Li^vi—Ta—Li^vii	75.4 (6)	O^xiv—Li—Nb^xv	83.5 (6)
Li^vii—Ta—Li^ix	117.3 (5)	O^xvi—Li—Nb^xiii	95.72 (7)
Li^viii—Ta—Liⁱ	71.68 (12)	O^xx—Li—Nb^xiii	37.76 (14)
Li^viii—Ta—Li^vii	75.4 (6)	O^xvii—Li—Nb^xiii	43.2 (2)
Li^x—Ta—Liⁱ	71.68 (12)	O^xiv—Li—O^xviii	72.8 (9)
Li^vi—Ta—Li^viii	113.8 (5)	O^xvi—Li—O^xviii	150.7 (15)
Li^vii—Ta—Liⁱ	117.3 (5)	O^xx—Li—O^xiv	72.8 (9)
Li^vi—Ta—Li^ix	71.68 (12)	O^xix—Li—O^xvii	110.8 (9)
Li^x—Ta—Li^vii	75.4 (6)	O^xvii—Li—O^xiv	150.7 (15)
Li^x—Ta—Li^ix	71.68 (12)	O^xix—Li—O^xvi	110.8 (9)
Li^vi—Ta—Li^x	113.8 (5)	O^xx—Li—O^xviii	72.8 (9)
Liⁱ—Ta—Li^ix	100.7 (7)	O^xix—Li—O^xiv	88.7 (4)
Li^viii—Ta—Li^x	113.8 (5)	O^xvii—Li—O^xviii	88.7 (4)
Li^viii—Ta—Li^ix	167.4 (12)	O^xvii—Li—O^xvi	110.8 (9)
Ta—O—Ta^xi	140.34 (12)	O^xvi—Li—O^xiv	80.2 (4)
Ta^xi—O—Nb^xi	0.0 (2)	O^xix—Li—O^xx	150.7 (15)
Ta—O—Nb^xi	140.3	O^xix—Li—O^xviii	80.2 (4)
Ta—O—Li^xii	116.8 (4)	O^xvii—Li—O^xx	80.2 (4)
Ta^xi—O—Li^viii	88.6 (6)	O^xvi—Li—O^xx	88.7 (4)

Symmetry codes: (i) −y+2/3, −x+1/3, z−1/6; (ii) −x+y−1/3, y−2/3, z−1/6; (iii) −x+y, −x, z; (iv) −y, x−y, z; (v) x−1/3, x−y+1/3, z−1/6; (vi) x−2/3, y−1/3, z−1/3; (vii) −y, −x, z−1/2; (viii) x+1/3, y+2/3, z−1/3; (ix) −y−1/3, −x−2/3, z−1/6; (x) x+1/3, y−1/3, z−1/3; (xi) −y+1/3, −x+2/3, z+1/6; (xii) −y−1/3, −x+1/3, z−1/6; (xiii) x+2/3, y+1/3, z+1/3; (xiv) x−1/3, y−2/3, z+1/3; (xv) x−1/3, y+1/3, z+1/3; (xvi) −y+1/3, −x−1/3, z+1/6; (xvii) x+1/3, x−y+2/3, z+1/6; (xviii) −x+y−1/3, −x+1/3, z+1/3; (xix) −x+y−2/3, y−1/3, z+1/6; (xx) −y+2/3, x−y+1/3, z+1/3.

lithium niobate tantalate (LNT53) top

Crystal data top

LiNb_0.47O₃Ta_0.53	D_x = 6.106 Mg m⁻³
M_r = 194.51	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 1391 reflections
a = 5.147 (1) Å	θ = 5.4–32.1°
c = 13.834 (5) Å	µ = 29.87 mm⁻¹
V = 317.39 (17) Å³	T = 293 K
Z = 6	Cube, clear green
F(000) = 510	0.15 × 0.12 × 0.08 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	255 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	255 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.033
Detector resolution: 10.2833 pixels mm^-1	θ_max = 32.6°, θ_min = 5.4°
ω scans	h = −7→7
Absorption correction: analytical CrysAlisPro 1.171.38.43d (Rigaku Oxford Diffraction, 2015) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm	k = −7→7
T_min = 0.069, T_max = 0.183	l = −20→20
1800 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0452P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.024	(Δ/σ)_max < 0.001
wR(F²) = 0.062	Δρ_max = 1.61 e Å⁻³
S = 1.16	Δρ_min = −0.95 e Å⁻³
255 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
17 parameters	Extinction coefficient: 0.150 (12)
1 restraint	Absolute structure: Flack x determined using 116 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
Primary atom site location: Other	Absolute structure parameter: −0.01 (6)

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ta	0.0000	0.0000	0.9983 (6)	0.0118 (4)	0.53
Nb	0.0000	0.0000	0.9983 (6)	0.0118 (4)	0.47
O	0.9519 (5)	0.6572 (7)	0.9321 (7)	0.0092 (7)
Li	0.0000	0.0000	0.718 (4)	0.007 (7)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.0115 (4)	0.0115 (4)	0.0124 (5)	0.0057 (2)	0.000	0.000
Nb	0.0115 (4)	0.0115 (4)	0.0124 (5)	0.0057 (2)	0.000	0.000
O	0.0088 (16)	0.0082 (11)	0.0109 (11)	0.0045 (17)	−0.0009 (18)	−0.0015 (6)
Li	0.003 (9)	0.003 (9)	0.016 (15)	0.001 (4)	0.000	0.000

Geometric parameters (Å, º) top

Ta—Oⁱ	1.891 (6)	O—Nb^xii	1.891 (6)
Ta—Oⁱⁱ	1.891 (6)	O—Li^xi	2.29 (4)
Ta—Oⁱⁱⁱ	1.891 (6)	O—Li^xiv	2.045 (16)
Ta—O^iv	2.102 (8)	Li—Ta^xv	3.062 (12)
Ta—O^v	2.102 (8)	Li—Ta^xvi	3.05 (5)
Ta—O^vi	2.102 (8)	Li—Ta^xvii	3.062 (12)
Ta—Li^vii	3.05 (5)	Li—Nb^xvii	3.062 (12)
Ta—Li^viii	3.062 (12)	Li—Nb^xv	3.062 (12)
Ta—Li^ix	3.062 (12)	Li—Nb^xvi	3.05 (5)
Ta—Li^x	3.36 (2)	Li—O^xviii	2.045 (16)
Ta—Li^xi	3.062 (12)	Li—O^xix	2.29 (4)
Ta—Li^iv	3.36 (2)	Li—O^xx	2.045 (16)
O—Ta^xii	1.891 (6)	Li—O^xxi	2.045 (16)
O—Ta^xiii	2.102 (8)	Li—O^xxii	2.29 (4)
O—Nb^xiii	2.102 (8)	Li—O^xvii	2.29 (4)

Oⁱ—Ta—Oⁱⁱⁱ	98.5 (4)	Nb^xii—O—Nb^xiii	140.7 (2)
O^v—Ta—O^iv	81.0 (4)	Nb^xiii—O—Li^xi	87.8 (9)
O^v—Ta—O^vi	81.0 (4)	Nb^xii—O—Li^xiv	117.1 (6)
Oⁱⁱ—Ta—O^iv	167.5 (5)	Nb^xii—O—Li^xi	93.8 (8)
Oⁱⁱⁱ—Ta—O^vi	167.5 (5)	Li^xiv—O—Ta^xiii	95.2 (10)
Oⁱⁱ—Ta—O^vi	88.88 (9)	Li^xiv—O—Nb^xiii	95.2 (10)
Oⁱ—Ta—O^v	167.5 (5)	Li^xiv—O—Li^xi	120.4 (10)
Oⁱ—Ta—Oⁱⁱ	98.5 (4)	Ta^xvii—Li—Ta^xv	114.4 (7)
Oⁱⁱⁱ—Ta—O^v	88.88 (10)	Ta^xvi—Li—Ta^xvii	76.0 (9)
Oⁱ—Ta—O^vi	90.21 (10)	Ta^xvi—Li—Ta^xv	76.0 (9)
Oⁱⁱ—Ta—O^v	90.21 (10)	Ta^xv—Li—Nb^xv	0.0 (3)
Oⁱⁱⁱ—Ta—Oⁱⁱ	98.5 (4)	Ta^xvii—Li—Nb^xv	114.4 (7)
Oⁱ—Ta—O^iv	88.88 (10)	Ta^xvi—Li—Nb^xvii	76.0 (9)
Oⁱⁱⁱ—Ta—O^iv	90.22 (10)	Ta^xvii—Li—Nb^xvii	0.0
O^iv—Ta—O^vi	81.0 (4)	Ta^xvi—Li—Nb^xv	76.0 (9)
O^iv—Ta—Li^viii	41.7 (7)	Ta^xvi—Li—Nb^xvi	0.000 (1)
Oⁱⁱ—Ta—Li^xi	48.2 (8)	Nb^xvii—Li—Ta^xv	114.4
Oⁱⁱⁱ—Ta—Li^viii	103.1 (4)	Nb^xvi—Li—Ta^xv	76.0
Oⁱⁱⁱ—Ta—Li^ix	48.2 (8)	Nb^xvi—Li—Ta^xvii	76.0
O^vi—Ta—Li^xi	41.7 (7)	Nb^xvi—Li—Nb^xv	76.0 (9)
O^v—Ta—Li^ix	41.7 (7)	Nb^xvi—Li—Nb^xvii	76.0 (9)
Oⁱ—Ta—Li^iv	119.3 (8)	Nb^xvii—Li—Nb^xv	114.4 (7)
O^v—Ta—Li^vii	48.6 (2)	O^xix—Li—Ta^xvii	38.0 (2)
O^v—Ta—Li^xi	76.2 (6)	O^xxii—Li—Ta^xvii	84.1 (9)
O^iv—Ta—Li^vii	48.6 (2)	O^xx—Li—Ta^xvi	108.5 (13)
Oⁱⁱ—Ta—Li^x	119.3 (8)	O^xvii—Li—Ta^xv	38.0 (2)
O^vi—Ta—Li^vii	48.6 (2)	O^xxi—Li—Ta^xvi	108.5 (13)
O^iv—Ta—Li^x	72.6 (7)	O^xx—Li—Ta^xv	95.56 (12)
Oⁱ—Ta—Li^xi	103.1 (4)	O^xxi—Li—Ta^xv	149.7 (3)
Oⁱⁱⁱ—Ta—Li^xi	142.3 (5)	O^xix—Li—Ta^xvi	43.6 (9)
Oⁱ—Ta—Li^vii	119.0 (3)	O^xviii—Li—Ta^xvi	108.5 (13)
O^v—Ta—Li^viii	120.4 (9)	O^xxii—Li—Ta^xvi	43.6 (9)
Oⁱⁱⁱ—Ta—Li^vii	119.0 (3)	O^xviii—Li—Ta^xv	43.1 (4)
Oⁱⁱ—Ta—Li^iv	32.83 (17)	O^xvii—Li—Ta^xvii	111.4 (15)
Oⁱⁱ—Ta—Li^vii	119.0 (3)	O^xvii—Li—Ta^xvi	43.6 (9)
Oⁱ—Ta—Li^viii	48.2 (8)	O^xix—Li—Ta^xv	84.1 (9)
Oⁱⁱⁱ—Ta—Li^x	32.83 (18)	O^xviii—Li—Ta^xvii	95.56 (11)
Oⁱ—Ta—Li^ix	142.3 (5)	O^xx—Li—Ta^xvii	149.7 (3)
O^v—Ta—Li^x	112.4 (5)	O^xxii—Li—Ta^xv	111.4 (15)
O^iv—Ta—Li^xi	120.4 (9)	O^xxi—Li—Ta^xvii	43.1 (4)
O^vi—Ta—Li^x	147.5 (5)	O^xviii—Li—Nb^xvii	95.56 (11)
Oⁱⁱ—Ta—Li^ix	103.1 (4)	O^xxii—Li—Nb^xvi	43.6 (9)
Oⁱⁱⁱ—Ta—Li^iv	71.0 (3)	O^xx—Li—Nb^xvi	108.5 (13)
Oⁱⁱ—Ta—Li^viii	142.3 (5)	O^xxi—Li—Nb^xvii	43.1 (4)
O^v—Ta—Li^iv	72.6 (7)	O^xvii—Li—Nb^xv	38.0 (2)
O^iv—Ta—Li^ix	76.2 (6)	O^xxii—Li—Nb^xv	111.4 (15)
O^vi—Ta—Li^iv	112.4 (5)	O^xvii—Li—Nb^xvi	43.6 (9)
O^iv—Ta—Li^iv	147.5 (4)	O^xx—Li—Nb^xvii	149.7 (3)
O^vi—Ta—Li^viii	76.2 (6)	O^xxii—Li—Nb^xvii	84.1 (9)
Oⁱ—Ta—Li^x	71.0 (3)	O^xix—Li—Nb^xv	84.1 (9)
O^vi—Ta—Li^ix	120.4 (9)	O^xxi—Li—Nb^xvi	108.5 (13)
Li^vii—Ta—Li^x	117.8 (8)	O^xix—Li—Nb^xvii	38.0 (2)
Li^vii—Ta—Li^iv	117.8 (8)	O^xviii—Li—Nb^xvi	108.5 (13)
Li^xi—Ta—Li^viii	114.4 (7)	O^xix—Li—Nb^xvi	43.6 (9)
Li^vii—Ta—Li^ix	76.0 (9)	O^xxi—Li—Nb^xv	149.7 (3)
Li^vii—Ta—Li^viii	76.0 (9)	O^xvii—Li—Nb^xvii	111.4 (15)
Li^ix—Ta—Li^iv	71.54 (19)	O^xx—Li—Nb^xv	95.56 (12)
Li^ix—Ta—Li^x	71.54 (19)	O^xviii—Li—Nb^xv	43.1 (4)
Li^xi—Ta—Li^x	166.2 (17)	O^xxi—Li—O^xvii	151 (2)
Li^viii—Ta—Li^ix	114.4 (7)	O^xxi—Li—O^xviii	110.4 (13)
Li^xi—Ta—Li^iv	71.54 (18)	O^xviii—Li—O^xix	88.9 (6)
Li^x—Ta—Li^iv	100.0 (10)	O^xvii—Li—O^xxii	73.3 (14)
Li^viii—Ta—Li^x	71.54 (18)	O^xviii—Li—O^xx	110.4 (13)
Li^vii—Ta—Li^xi	76.0 (9)	O^xxi—Li—O^xix	80.3 (6)
Li^xi—Ta—Li^ix	114.4 (7)	O^xix—Li—O^xxii	73.3 (14)
Li^viii—Ta—Li^iv	166.2 (17)	O^xviii—Li—O^xvii	80.3 (6)
Ta^xii—O—Ta^xiii	140.7 (2)	O^xxi—Li—O^xxii	88.9 (6)
Ta^xiii—O—Nb^xiii	0.000 (1)	O^xxi—Li—O^xx	110.4 (13)
Ta^xii—O—Nb^xiii	140.7 (2)	O^xviii—Li—O^xxii	151 (2)
Ta^xiii—O—Li^xi	87.8 (9)	O^xx—Li—O^xvii	88.9 (6)
Ta^xii—O—Li^xiv	117.1 (6)	O^xx—Li—O^xxii	80.3 (6)
Ta^xii—O—Li^xi	93.8 (8)	O^xx—Li—O^xix	151 (2)
Nb^xii—O—Ta^xii	0.0	O^xix—Li—O^xvii	73.3 (14)
Nb^xii—O—Ta^xiii	140.7

Symmetry codes: (i) x−1, y−1, z; (ii) −y+1, x−y, z; (iii) −x+y, −x+1, z; (iv) −y+1/3, −x+2/3, z+1/6; (v) −x+y+1/3, y−1/3, z+1/6; (vi) x−2/3, x−y−1/3, z+1/6; (vii) −y, −x, z+1/2; (viii) x−1/3, y−2/3, z+1/3; (ix) x−1/3, y+1/3, z+1/3; (x) −y−2/3, −x−1/3, z+1/6; (xi) x+2/3, y+1/3, z+1/3; (xii) x+1, y+1, z; (xiii) −y+2/3, −x+1/3, z−1/6; (xiv) −y+4/3, −x+2/3, z+1/6; (xv) x+1/3, y+2/3, z−1/3; (xvi) −y, −x, z−1/2; (xvii) x−2/3, y−1/3, z−1/3; (xviii) −y+2/3, −x+4/3, z−1/6; (xix) −y+1/3, x−y−1/3, z−1/3; (xx) −x+y+2/3, y−2/3, z−1/6; (xxi) x−4/3, x−y−2/3, z−1/6; (xxii) −x+y+1/3, −x+2/3, z−1/3.

lithium niobate tantalate (LNT60) top

Crystal data top

LiNb_0.40O₃Ta_0.60	D_x = 6.316 Mg m⁻³
M_r = 200.67	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 2949 reflections
a = 5.147 (1) Å	θ = 4.8–37.2°
c = 13.798 (5) Å	µ = 33.19 mm⁻¹
V = 316.56 (17) Å³	T = 294 K
Z = 6	Block, clear green
F(000) = 523	0.22 × 0.15 × 0.13 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	372 independent reflections
Radiation source: Enhance (Mo) X-ray Source	365 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.043
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.4°, θ_min = 5.5°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.015, T_max = 0.099	l = −23→22
3999 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0225P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.014	(Δ/σ)_max < 0.001
wR(F²) = 0.036	Δρ_max = 2.17 e Å⁻³
S = 1.18	Δρ_min = −0.79 e Å⁻³
372 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
18 parameters	Extinction coefficient: 0.0277 (15)
1 restraint	Absolute structure: Refined as an inversion twin.
Primary atom site location: Other	Absolute structure parameter: 0.29 (10)

Special details top

Refinement. Refined as a 2-component inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ta	0.0000	0.0000	0.0018 (4)	0.00362 (13)	0.6
Nb	0.0000	0.0000	0.0018 (4)	0.00362 (13)	0.4
O	0.0491 (3)	0.3431 (4)	0.0695 (4)	0.0071 (3)
Li	0.0000	0.0000	0.283 (2)	0.015 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.00367 (15)	0.00367 (15)	0.00351 (16)	0.00184 (7)	0.000	0.000
Nb	0.00367 (15)	0.00367 (15)	0.00351 (16)	0.00184 (7)	0.000	0.000
O	0.0071 (8)	0.0065 (5)	0.0076 (4)	0.0034 (8)	−0.0014 (7)	−0.0016 (3)
Li	0.014 (6)	0.014 (6)	0.018 (9)	0.007 (3)	0.000	0.000

Geometric parameters (Å, º) top

Ta—O	1.900 (3)	O—Li^vi	2.28 (2)
Ta—Oⁱ	1.900 (3)	O—Li^xii	2.048 (10)
Ta—Oⁱⁱ	1.900 (3)	Li—Ta^xiii	3.02 (3)
Ta—Oⁱⁱⁱ	2.084 (4)	Li—Ta^xiv	3.058 (8)
Ta—O^iv	2.084 (4)	Li—Ta^xv	3.058 (8)
Ta—O^v	2.084 (4)	Li—Nb^xv	3.058 (8)
Ta—Liⁱⁱⁱ	3.364 (15)	Li—Nb^xiv	3.058 (8)
Ta—Li^vi	3.058 (8)	Li—Nb^xiii	3.02 (3)
Ta—Li^vii	3.364 (15)	Li—O^xvi	2.048 (10)
Ta—Li^viii	3.058 (8)	Li—O^xvii	2.28 (2)
Ta—Li^ix	3.058 (8)	Li—O^xviii	2.048 (10)
Ta—Li^x	3.02 (3)	Li—O^xix	2.048 (10)
O—Ta^xi	2.084 (4)	Li—O^xiv	2.28 (2)
O—Nb^xi	2.084 (4)	Li—O^xx	2.28 (2)

O—Ta—Oⁱⁱ	97.90 (18)	Ta^xi—O—Li^vi	87.4 (6)
O^iv—Ta—Oⁱⁱⁱ	81.70 (17)	Nb^xi—O—Li^vi	87.4 (6)
O^iv—Ta—O^v	81.70 (17)	Li^xii—O—Ta^xi	95.5 (6)
Oⁱ—Ta—Oⁱⁱⁱ	168.4 (3)	Li^xii—O—Nb^xi	95.5 (6)
Oⁱⁱ—Ta—O^v	168.4 (3)	Li^xii—O—Li^vi	120.2 (6)
Oⁱ—Ta—O^v	88.93 (4)	Ta^xv—Li—Ta^xiv	114.6 (4)
O—Ta—O^iv	168.4 (3)	Ta^xiii—Li—Ta^xv	76.3 (6)
O—Ta—Oⁱ	97.91 (18)	Ta^xiii—Li—Ta^xiv	76.3 (6)
Oⁱⁱ—Ta—O^iv	88.93 (4)	Ta^xv—Li—Nb^xiv	114.6 (4)
O—Ta—O^v	90.31 (5)	Ta^xiii—Li—Nb^xv	76.3 (6)
Oⁱ—Ta—O^iv	90.31 (5)	Ta^xv—Li—Nb^xv	0.00 (19)
Oⁱⁱ—Ta—Oⁱ	97.90 (18)	Ta^xiii—Li—Nb^xiv	76.3 (6)
O—Ta—Oⁱⁱⁱ	88.93 (4)	Ta^xiv—Li—Nb^xiv	0.0
Oⁱⁱ—Ta—Oⁱⁱⁱ	90.31 (5)	Ta^xiii—Li—Nb^xiii	0.0
Oⁱⁱⁱ—Ta—O^v	81.70 (17)	Nb^xiii—Li—Ta^xv	76.3
Oⁱⁱⁱ—Ta—Li^vi	41.8 (4)	Nb^xv—Li—Ta^xiv	114.6
Oⁱ—Ta—Li^ix	48.2 (5)	Nb^xiii—Li—Ta^xiv	76.3
Oⁱⁱ—Ta—Li^vi	103.2 (3)	Nb^xv—Li—Nb^xiv	114.6 (4)
Oⁱⁱ—Ta—Li^viii	48.2 (5)	Nb^xiii—Li—Nb^xv	76.3 (6)
O^v—Ta—Li^ix	41.8 (4)	Nb^xiii—Li—Nb^xiv	76.3 (6)
O^iv—Ta—Li^viii	41.8 (4)	O^xvii—Li—Ta^xv	38.32 (13)
O—Ta—Li^vii	118.7 (5)	O^xiv—Li—Ta^xv	111.6 (10)
O^iv—Ta—Li^x	49.05 (11)	O^xviii—Li—Ta^xiii	108.3 (9)
O^iv—Ta—Li^ix	76.3 (4)	O^xx—Li—Ta^xiv	111.6 (10)
Oⁱⁱⁱ—Ta—Li^x	49.05 (11)	O^xx—Li—Ta^xiii	43.5 (6)
Oⁱ—Ta—Liⁱⁱⁱ	118.7 (5)	O^xvii—Li—Ta^xiv	84.4 (6)
O^v—Ta—Li^x	49.05 (11)	O^xviii—Li—Ta^xv	149.6 (2)
Oⁱⁱⁱ—Ta—Liⁱⁱⁱ	72.3 (5)	O^xiv—Li—Ta^xiii	43.5 (6)
O—Ta—Li^ix	103.2 (3)	O^xvi—Li—Ta^xiii	108.3 (9)
Oⁱⁱ—Ta—Li^ix	141.9 (3)	O^xix—Li—Ta^xv	42.7 (2)
O—Ta—Li^x	119.44 (14)	O^xvii—Li—Ta^xiii	43.5 (6)
O^iv—Ta—Li^vi	121.2 (6)	O^xix—Li—Ta^xiii	108.3 (9)
Oⁱⁱ—Ta—Li^x	119.44 (14)	O^xviii—Li—Ta^xiv	95.45 (6)
Oⁱ—Ta—Li^vii	32.88 (11)	O^xiv—Li—Ta^xiv	38.32 (13)
O^v—Ta—Li^viii	121.2 (6)	O^xvi—Li—Ta^xiv	42.7 (2)
O—Ta—Li^vi	48.2 (5)	O^xx—Li—Ta^xv	84.4 (6)
Oⁱⁱ—Ta—Liⁱⁱⁱ	32.88 (11)	O^xvi—Li—Ta^xv	95.45 (5)
O^v—Ta—Li^vi	76.3 (4)	O^xix—Li—Ta^xiv	149.6 (2)
O^iv—Ta—Liⁱⁱⁱ	112.4 (3)	O^xviii—Li—Nb^xv	149.6 (2)
Oⁱⁱⁱ—Ta—Li^ix	121.2 (6)	O^xix—Li—Nb^xiii	108.3 (9)
O^v—Ta—Liⁱⁱⁱ	147.6 (3)	O^xvi—Li—Nb^xiv	42.7 (2)
Oⁱ—Ta—Li^viii	103.2 (3)	O^xx—Li—Nb^xiv	111.6 (10)
Oⁱⁱ—Ta—Li^vii	70.6 (2)	O^xviii—Li—Nb^xiv	95.45 (6)
Oⁱ—Ta—Li^vi	141.9 (3)	O^xix—Li—Nb^xiv	149.6 (2)
O^iv—Ta—Li^vii	72.3 (5)	O^xiv—Li—Nb^xiv	38.32 (13)
Oⁱⁱⁱ—Ta—Li^viii	76.3 (4)	O^xix—Li—Nb^xv	42.7 (2)
O^v—Ta—Li^vii	112.4 (3)	O^xiv—Li—Nb^xv	111.6 (10)
Oⁱⁱⁱ—Ta—Li^vii	147.6 (3)	O^xx—Li—Nb^xiii	43.5 (6)
O—Ta—Li^viii	141.9 (3)	O^xx—Li—Nb^xv	84.4 (6)
O—Ta—Liⁱⁱⁱ	70.6 (2)	O^xvi—Li—Nb^xv	95.45 (5)
Oⁱ—Ta—Li^x	119.44 (14)	O^xviii—Li—Nb^xiii	108.3 (9)
Li^x—Ta—Liⁱⁱⁱ	118.0 (5)	O^xvii—Li—Nb^xiv	84.4 (6)
Li^x—Ta—Li^vii	118.0 (5)	O^xvi—Li—Nb^xiii	108.3 (9)
Li^ix—Ta—Li^vi	114.6 (4)	O^xvii—Li—Nb^xv	38.32 (13)
Li^x—Ta—Li^viii	76.3 (6)	O^xiv—Li—Nb^xiii	43.5 (6)
Li^x—Ta—Li^vi	76.3 (6)	O^xvii—Li—Nb^xiii	43.5 (6)
Li^viii—Ta—Li^vii	71.44 (12)	O^xiv—Li—O^xx	73.2 (9)
Li^viii—Ta—Liⁱⁱⁱ	71.44 (12)	O^xix—Li—O^xx	88.8 (4)
Li^ix—Ta—Liⁱⁱⁱ	165.7 (11)	O^xviii—Li—O^xx	80.1 (4)
Li^vi—Ta—Li^vii	165.7 (11)	O^xvi—Li—O^xx	151.1 (14)
Li^ix—Ta—Li^viii	114.6 (4)	O^xvi—Li—O^xiv	80.1 (4)
Liⁱⁱⁱ—Ta—Li^vii	99.8 (6)	O^xvii—Li—O^xiv	73.2 (9)
Li^vi—Ta—Liⁱⁱⁱ	71.44 (12)	O^xvi—Li—O^xvii	88.8 (4)
Li^ix—Ta—Li^vii	71.44 (12)	O^xviii—Li—O^xix	110.6 (8)
Li^x—Ta—Li^ix	76.3 (6)	O^xix—Li—O^xvi	110.6 (8)
Li^vi—Ta—Li^viii	114.6 (4)	O^xix—Li—O^xiv	151.1 (14)
Ta—O—Ta^xi	141.18 (9)	O^xviii—Li—O^xvii	151.1 (14)
Ta^xi—O—Nb^xi	0.0 (2)	O^xviii—Li—O^xvi	110.6 (8)
Ta—O—Nb^xi	141.2	O^xix—Li—O^xvii	80.1 (4)
Ta—O—Li^xii	116.9 (4)	O^xvii—Li—O^xx	73.2 (9)
Ta—O—Li^vi	93.5 (5)	O^xviii—Li—O^xiv	88.8 (4)

Symmetry codes: (i) −y, x−y, z; (ii) −x+y, −x, z; (iii) −y+2/3, −x+1/3, z−1/6; (iv) −x+y−1/3, y−2/3, z−1/6; (v) x−1/3, x−y+1/3, z−1/6; (vi) x+1/3, y+2/3, z−1/3; (vii) −y−1/3, −x−2/3, z−1/6; (viii) x+1/3, y−1/3, z−1/3; (ix) x−2/3, y−1/3, z−1/3; (x) −y, −x, z−1/2; (xi) −y+1/3, −x+2/3, z+1/6; (xii) −y−1/3, −x+1/3, z−1/6; (xiii) −y, −x, z+1/2; (xiv) x−1/3, y−2/3, z+1/3; (xv) x+2/3, y+1/3, z+1/3; (xvi) −y+1/3, −x−1/3, z+1/6; (xvii) −y+2/3, x−y+1/3, z+1/3; (xviii) −x+y−2/3, y−1/3, z+1/6; (xix) x+1/3, x−y+2/3, z+1/6; (xx) −x+y−1/3, −x+1/3, z+1/3.

lithium niobate tantalate (LNT64) top

Crystal data top

LiNb_0.36O₃Ta_0.64	D_x = 6.427 Mg m⁻³
M_r = 204.20	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 2942 reflections
a = 5.149 (1) Å	θ = 4.8–37.2°
c = 13.786 (5) Å	µ = 35.05 mm⁻¹
V = 316.53 (17) Å³	T = 294 K
Z = 6	Block, clear green
F(000) = 531	0.18 × 0.14 × 0.13 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	372 independent reflections
Radiation source: Enhance (Mo) X-ray Source	355 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.048
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.4°, θ_min = 5.5°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.027, T_max = 0.106	l = −23→23
4354 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0247P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.016	(Δ/σ)_max < 0.001
wR(F²) = 0.042	Δρ_max = 0.78 e Å⁻³
S = 1.22	Δρ_min = −3.34 e Å⁻³
372 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
18 parameters	Extinction coefficient: 0.0243 (16)
1 restraint	Absolute structure: Refined as an inversion twin.
Primary atom site location: Other	Absolute structure parameter: 0.33 (12)

Special details top

Refinement. Refined as a 2-component inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ta	0.0000	0.0000	0.0020 (4)	0.00343 (16)	0.64
Nb	0.0000	0.0000	0.0020 (4)	0.00343 (16)	0.36
O	0.0485 (4)	0.3420 (6)	0.0692 (5)	0.0094 (4)
Li	0.0000	0.0000	0.285 (3)	0.015 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.00366 (18)	0.00366 (18)	0.00297 (19)	0.00183 (9)	0.000	0.000
Nb	0.00366 (18)	0.00366 (18)	0.00297 (19)	0.00183 (9)	0.000	0.000
O	0.0091 (11)	0.0093 (7)	0.0096 (6)	0.0044 (12)	−0.0007 (11)	−0.0017 (5)
Li	0.014 (7)	0.014 (7)	0.018 (11)	0.007 (4)	0.000	0.000

Geometric parameters (Å, º) top

Ta—O	1.893 (4)	O—Li^vi	2.26 (3)
Ta—Oⁱ	2.091 (5)	O—Li^xii	2.059 (12)
Ta—Oⁱⁱ	2.091 (5)	Li—Ta^xiii	2.99 (4)
Ta—Oⁱⁱⁱ	1.893 (4)	Li—Ta^xiv	3.052 (8)
Ta—O^iv	1.893 (4)	Li—Ta^xv	3.052 (8)
Ta—O^v	2.091 (5)	Li—Nb^xiv	3.052 (8)
Ta—Li^vi	3.052 (8)	Li—Nb^xiii	2.99 (4)
Ta—Li^vii	2.99 (4)	Li—Nb^xv	3.052 (8)
Ta—Li^viii	3.052 (8)	Li—O^xvi	2.059 (12)
Ta—Li^ix	3.378 (18)	Li—O^xv	2.26 (3)
Ta—Li^x	3.052 (8)	Li—O^xvii	2.059 (12)
Ta—Liⁱⁱ	3.378 (18)	Li—O^xviii	2.26 (3)
O—Ta^xi	2.091 (5)	Li—O^xix	2.26 (3)
O—Nb^xi	2.091 (5)	Li—O^xx	2.059 (12)

O—Ta—O^iv	98.1 (2)	Ta—O—Li^vi	94.1 (6)
O^iv—Ta—Oⁱ	88.92 (6)	Nb^xi—O—Li^vi	86.7 (7)
O—Ta—Oⁱⁱ	88.92 (6)	Li^xii—O—Ta^xi	94.7 (7)
Oⁱ—Ta—Oⁱⁱ	81.7 (2)	Li^xii—O—Nb^xi	94.7 (7)
Oⁱⁱⁱ—Ta—Oⁱ	90.15 (6)	Li^xii—O—Li^vi	120.7 (7)
Oⁱ—Ta—O^v	81.7 (2)	Ta^xiii—Li—Ta^xv	76.9 (7)
O—Ta—Oⁱⁱⁱ	98.1 (2)	Ta^xiv—Li—Ta^xv	115.0 (5)
Oⁱⁱⁱ—Ta—Oⁱⁱ	168.3 (3)	Ta^xiii—Li—Ta^xiv	76.9 (7)
O—Ta—O^v	90.14 (6)	Ta^xiv—Li—Nb^xv	115.0 (5)
O^iv—Ta—O^v	168.3 (3)	Ta^xiii—Li—Nb^xiii	0.0
O^iv—Ta—Oⁱⁱⁱ	98.1 (2)	Ta^xv—Li—Nb^xv	0.0
Oⁱⁱⁱ—Ta—O^v	88.92 (6)	Ta^xiv—Li—Nb^xiv	0.0 (2)
O^iv—Ta—Oⁱⁱ	90.15 (6)	Ta^xiii—Li—Nb^xv	76.9 (7)
O—Ta—Oⁱ	168.3 (3)	Ta^xiii—Li—Nb^xiv	76.9 (7)
Oⁱⁱ—Ta—O^v	81.7 (2)	Nb^xiii—Li—Ta^xiv	76.9
O—Ta—Li^vii	119.32 (18)	Nb^xiv—Li—Ta^xv	115.0
Oⁱⁱ—Ta—Li^ix	147.8 (3)	Nb^xiii—Li—Ta^xv	76.9
Oⁱⁱ—Ta—Liⁱⁱ	72.7 (5)	Nb^xiv—Li—Nb^xv	115.0 (5)
O^iv—Ta—Li^vii	119.32 (18)	Nb^xiii—Li—Nb^xv	76.9 (7)
Oⁱⁱⁱ—Ta—Liⁱⁱ	118.4 (5)	Nb^xiii—Li—Nb^xiv	76.9 (7)
O^v—Ta—Li^x	121.7 (7)	O^xviii—Li—Ta^xiv	38.21 (14)
O^iv—Ta—Li^viii	141.7 (4)	O^xvii—Li—Ta^xv	149.5 (3)
O^v—Ta—Li^vi	76.6 (4)	O^xx—Li—Ta^xv	95.34 (8)
O—Ta—Liⁱⁱ	70.5 (2)	O^xv—Li—Ta^xiv	112.6 (11)
Oⁱⁱ—Ta—Li^viii	121.7 (7)	O^xviii—Li—Ta^xiii	44.3 (7)
O^v—Ta—Li^vii	49.04 (14)	O^xx—Li—Ta^xiii	109.2 (10)
Oⁱⁱⁱ—Ta—Li^x	102.8 (3)	O^xvi—Li—Ta^xv	43.1 (2)
O—Ta—Li^viii	102.8 (3)	O^xix—Li—Ta^xv	112.6 (11)
Oⁱⁱⁱ—Ta—Li^vi	141.7 (4)	O^xvii—Li—Ta^xiv	43.1 (2)
Oⁱⁱ—Ta—Li^x	76.6 (4)	O^xix—Li—Ta^xiii	44.3 (7)
Oⁱ—Ta—Li^vi	121.7 (7)	O^xvii—Li—Ta^xiii	109.2 (10)
Oⁱⁱ—Ta—Li^vi	42.2 (5)	O^xviii—Li—Ta^xv	85.1 (6)
Oⁱⁱⁱ—Ta—Li^ix	32.74 (12)	O^xv—Li—Ta^xv	38.21 (14)
Oⁱⁱⁱ—Ta—Li^viii	47.7 (6)	O^xx—Li—Ta^xiv	149.5 (3)
O^iv—Ta—Liⁱⁱ	32.74 (12)	O^xvi—Li—Ta^xiv	95.34 (8)
O^iv—Ta—Li^vi	102.8 (3)	O^xv—Li—Ta^xiii	44.3 (7)
Oⁱ—Ta—Liⁱⁱ	112.7 (3)	O^xvi—Li—Ta^xiii	109.2 (10)
O^iv—Ta—Li^x	47.7 (6)	O^xix—Li—Ta^xiv	85.1 (6)
O^v—Ta—Liⁱⁱ	147.8 (3)	O^xx—Li—Nb^xiv	149.5 (3)
O^v—Ta—Li^viii	42.2 (5)	O^xviii—Li—Nb^xiii	44.3 (7)
O^iv—Ta—Li^ix	70.5 (2)	O^xx—Li—Nb^xiii	109.2 (10)
Oⁱ—Ta—Li^x	42.2 (5)	O^xvii—Li—Nb^xiii	109.2 (10)
Oⁱ—Ta—Li^ix	72.7 (5)	O^xix—Li—Nb^xiv	85.1 (6)
O—Ta—Li^ix	118.4 (5)	O^xvi—Li—Nb^xv	43.1 (2)
O^v—Ta—Li^ix	112.7 (3)	O^xvi—Li—Nb^xiii	109.2 (10)
Oⁱ—Ta—Li^vii	49.04 (14)	O^xix—Li—Nb^xv	112.6 (11)
O—Ta—Li^x	141.7 (4)	O^xix—Li—Nb^xiii	44.3 (7)
Oⁱ—Ta—Li^viii	76.6 (4)	O^xx—Li—Nb^xv	95.34 (8)
Oⁱⁱⁱ—Ta—Li^vii	119.32 (18)	O^xvi—Li—Nb^xiv	95.34 (8)
Oⁱⁱ—Ta—Li^vii	49.04 (14)	O^xvii—Li—Nb^xv	149.5 (3)
O—Ta—Li^vi	47.7 (6)	O^xviii—Li—Nb^xv	85.1 (6)
Li^vii—Ta—Liⁱⁱ	118.4 (6)	O^xv—Li—Nb^xv	38.21 (14)
Li^vi—Ta—Li^ix	164.8 (12)	O^xviii—Li—Nb^xiv	38.21 (14)
Li^vii—Ta—Li^viii	76.9 (7)	O^xvii—Li—Nb^xiv	43.1 (2)
Li^vii—Ta—Li^ix	118.4 (6)	O^xv—Li—Nb^xiv	112.6 (11)
Li^vi—Ta—Liⁱⁱ	71.30 (15)	O^xv—Li—Nb^xiii	44.3 (7)
Li^viii—Ta—Li^vi	115.0 (5)	O^xv—Li—O^xix	74.4 (10)
Li^viii—Ta—Liⁱⁱ	164.8 (12)	O^xvii—Li—O^xvi	109.7 (10)
Li^vii—Ta—Li^x	76.9 (7)	O^xvii—Li—O^xviii	80.4 (4)
Liⁱⁱ—Ta—Li^ix	99.3 (7)	O^xvii—Li—O^xix	89.1 (4)
Li^vii—Ta—Li^vi	76.9 (7)	O^xx—Li—O^xviii	152.8 (16)
Li^viii—Ta—Li^ix	71.30 (15)	O^xx—Li—O^xix	80.4 (4)
Li^x—Ta—Li^ix	71.30 (15)	O^xx—Li—O^xv	89.1 (4)
Li^vi—Ta—Li^x	115.0 (5)	O^xvi—Li—O^xix	152.8 (16)
Li^x—Ta—Liⁱⁱ	71.30 (15)	O^xvii—Li—O^xv	152.8 (16)
Li^viii—Ta—Li^x	115.0 (5)	O^xvi—Li—O^xv	80.4 (4)
Ta—O—Ta^xi	141.09 (12)	O^xx—Li—O^xvi	109.7 (10)
Ta^xi—O—Nb^xi	0.0 (2)	O^xviii—Li—O^xv	74.4 (10)
Ta—O—Nb^xi	141.1	O^xviii—Li—O^xix	74.4 (10)
Ta—O—Li^xii	117.4 (4)	O^xvi—Li—O^xviii	89.1 (4)
Ta^xi—O—Li^vi	86.7 (7)	O^xx—Li—O^xvii	109.7 (10)

Symmetry codes: (i) −x+y−1/3, y−2/3, z−1/6; (ii) −y+2/3, −x+1/3, z−1/6; (iii) −y, x−y, z; (iv) −x+y, −x, z; (v) x−1/3, x−y+1/3, z−1/6; (vi) x+1/3, y+2/3, z−1/3; (vii) −y, −x, z−1/2; (viii) x−2/3, y−1/3, z−1/3; (ix) −y−1/3, −x−2/3, z−1/6; (x) x+1/3, y−1/3, z−1/3; (xi) −y+1/3, −x+2/3, z+1/6; (xii) −y−1/3, −x+1/3, z−1/6; (xiii) −y, −x, z+1/2; (xiv) x+2/3, y+1/3, z+1/3; (xv) x−1/3, y−2/3, z+1/3; (xvi) −y+1/3, −x−1/3, z+1/6; (xvii) x+1/3, x−y+2/3, z+1/6; (xviii) −y+2/3, x−y+1/3, z+1/3; (xix) −x+y−1/3, −x+1/3, z+1/3; (xx) −x+y−2/3, y−1/3, z+1/6.

lithium niobate tantalate (LNT89) top

Crystal data top

LiNb_0.11O₃Ta_0.89	D_x = 7.120 Mg m⁻³
M_r = 226.21	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 3255 reflections
a = 5.151 (1) Å	θ = 4.8–37.2°
c = 13.776 (5) Å	µ = 46.64 mm⁻¹
V = 316.55 (17) Å³	T = 293 K
Z = 6	Block, clear green
F(000) = 579	0.30 × 0.24 × 0.19 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	375 independent reflections
Radiation source: Enhance (Mo) X-ray Source	371 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.053
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.6°, θ_min = 5.5°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.005, T_max = 0.043	l = −23→22
4378 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.027P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.017	(Δ/σ)_max < 0.001
wR(F²) = 0.042	Δρ_max = 2.57 e Å⁻³
S = 1.23	Δρ_min = −1.16 e Å⁻³
375 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
18 parameters	Extinction coefficient: 0.0193 (12)
1 restraint	Absolute structure: Refined as an inversion twin.
Primary atom site location: Other	Absolute structure parameter: 0.53 (12)

Special details top

Refinement. Refined as a 2-component inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ta	0.0000	0.0000	0.0014 (5)	0.00457 (15)	0.89
Nb	0.0000	0.0000	0.0014 (5)	0.00457 (15)	0.11
O	0.0497 (3)	0.3438 (3)	0.0700 (5)	0.0066 (3)
Li	0.0000	0.0000	0.282 (3)	0.012 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.00532 (16)	0.00532 (16)	0.00307 (18)	0.00266 (8)	0.000	0.000
Nb	0.00532 (16)	0.00532 (16)	0.00307 (18)	0.00266 (8)	0.000	0.000
O	0.0077 (7)	0.0060 (5)	0.0063 (4)	0.0035 (7)	−0.0018 (7)	−0.0024 (3)
Li	0.010 (7)	0.010 (7)	0.016 (12)	0.005 (4)	0.000	0.000

Geometric parameters (Å, º) top

Ta—Oⁱ	1.908 (4)	O—Li^vi	2.30 (3)
Ta—Oⁱⁱ	2.073 (5)	O—Li^xii	2.044 (13)
Ta—Oⁱⁱⁱ	2.073 (5)	Li—Ta^xiii	3.02 (4)
Ta—O	1.908 (4)	Li—Ta^xiv	3.062 (10)
Ta—O^iv	1.908 (4)	Li—Ta^xv	3.062 (10)
Ta—O^v	2.073 (5)	Li—Nb^xiv	3.062 (10)
Ta—Li^vi	3.062 (10)	Li—Nb^xiii	3.02 (4)
Ta—Li^vii	3.02 (4)	Li—Nb^xv	3.062 (10)
Ta—Li^viii	3.062 (10)	Li—O^xvi	2.044 (13)
Ta—Li^ix	3.36 (2)	Li—O^xv	2.30 (3)
Ta—Li^x	3.062 (10)	Li—O^xvii	2.044 (13)
Ta—Liⁱⁱⁱ	3.36 (2)	Li—O^xviii	2.30 (3)
O—Ta^xi	2.073 (5)	Li—O^xix	2.30 (3)
O—Nb^xi	2.073 (5)	Li—O^xx	2.044 (13)

Oⁱ—Ta—O^iv	97.6 (2)	Ta—O—Li^vi	93.1 (6)
O^iv—Ta—Oⁱⁱ	90.36 (5)	Nb^xi—O—Li^vi	87.5 (7)
Oⁱ—Ta—Oⁱⁱⁱ	90.36 (5)	Li^xii—O—Ta^xi	96.1 (8)
Oⁱⁱ—Ta—Oⁱⁱⁱ	82.1 (2)	Li^xii—O—Nb^xi	96.1 (8)
O—Ta—Oⁱⁱ	168.9 (3)	Li^xii—O—Li^vi	119.8 (9)
Oⁱⁱ—Ta—O^v	82.1 (2)	Ta^xiii—Li—Ta^xv	76.2 (8)
Oⁱ—Ta—O	97.6 (2)	Ta^xiv—Li—Ta^xv	114.5 (6)
O—Ta—Oⁱⁱⁱ	88.89 (5)	Ta^xiii—Li—Ta^xiv	76.2 (8)
Oⁱ—Ta—O^v	168.9 (3)	Ta^xiv—Li—Nb^xv	114.5 (6)
O^iv—Ta—O^v	88.89 (5)	Ta^xiii—Li—Nb^xiii	0.0
O^iv—Ta—O	97.6 (2)	Ta^xv—Li—Nb^xv	0.0
O—Ta—O^v	90.36 (5)	Ta^xiv—Li—Nb^xiv	0.0 (2)
O^iv—Ta—Oⁱⁱⁱ	168.9 (3)	Ta^xiii—Li—Nb^xv	76.2 (8)
Oⁱ—Ta—Oⁱⁱ	88.89 (5)	Ta^xiii—Li—Nb^xiv	76.2 (8)
Oⁱⁱⁱ—Ta—O^v	82.1 (2)	Nb^xiii—Li—Ta^xiv	76.2
Oⁱ—Ta—Li^vii	119.67 (19)	Nb^xiv—Li—Ta^xv	114.5
Oⁱⁱⁱ—Ta—Li^ix	147.6 (4)	Nb^xiii—Li—Ta^xv	76.2
Oⁱⁱⁱ—Ta—Liⁱⁱⁱ	71.9 (6)	Nb^xiv—Li—Nb^xv	114.5 (6)
O^iv—Ta—Li^vii	119.67 (19)	Nb^xiii—Li—Nb^xv	76.2 (8)
O—Ta—Liⁱⁱⁱ	70.5 (3)	Nb^xiii—Li—Nb^xiv	76.2 (8)
O^v—Ta—Li^x	121.3 (7)	O^xviii—Li—Ta^xiv	38.48 (16)
O^iv—Ta—Li^viii	48.5 (7)	O^xvii—Li—Ta^xv	42.3 (3)
O^v—Ta—Li^vi	76.3 (5)	O^xx—Li—Ta^xv	149.6 (2)
Oⁱ—Ta—Liⁱⁱⁱ	32.96 (14)	O^xv—Li—Ta^xiv	111.2 (13)
Oⁱⁱⁱ—Ta—Li^viii	121.3 (7)	O^xviii—Li—Ta^xiii	43.2 (7)
O^v—Ta—Li^vii	49.31 (15)	O^xx—Li—Ta^xiii	107.8 (11)
O—Ta—Li^x	141.8 (4)	O^xvi—Li—Ta^xv	95.43 (6)
Oⁱ—Ta—Li^viii	141.8 (4)	O^xix—Li—Ta^xv	111.2 (13)
O—Ta—Li^vi	48.5 (7)	O^xvii—Li—Ta^xiv	95.43 (6)
Oⁱⁱⁱ—Ta—Li^x	76.3 (5)	O^xix—Li—Ta^xiii	43.2 (7)
Oⁱⁱ—Ta—Li^vi	121.3 (7)	O^xvii—Li—Ta^xiii	107.8 (11)
Oⁱⁱⁱ—Ta—Li^vi	41.6 (6)	O^xviii—Li—Ta^xv	84.3 (7)
O—Ta—Li^ix	118.7 (6)	O^xv—Li—Ta^xv	38.48 (16)
O—Ta—Li^viii	103.3 (4)	O^xx—Li—Ta^xiv	42.3 (3)
O^iv—Ta—Liⁱⁱⁱ	118.7 (6)	O^xvi—Li—Ta^xiv	149.6 (2)
O^iv—Ta—Li^vi	141.8 (4)	O^xv—Li—Ta^xiii	43.2 (7)
Oⁱⁱ—Ta—Liⁱⁱⁱ	112.3 (4)	O^xvi—Li—Ta^xiii	107.8 (11)
O^iv—Ta—Li^x	103.3 (4)	O^xix—Li—Ta^xiv	84.3 (7)
O^v—Ta—Liⁱⁱⁱ	147.6 (4)	O^xx—Li—Nb^xiv	42.3 (3)
O^v—Ta—Li^viii	41.6 (6)	O^xviii—Li—Nb^xiii	43.2 (7)
O^iv—Ta—Li^ix	32.96 (14)	O^xx—Li—Nb^xiii	107.8 (11)
Oⁱⁱ—Ta—Li^x	41.6 (6)	O^xvii—Li—Nb^xiii	107.8 (11)
Oⁱⁱ—Ta—Li^ix	71.9 (6)	O^xix—Li—Nb^xiv	84.3 (7)
Oⁱ—Ta—Li^ix	70.5 (3)	O^xvi—Li—Nb^xv	95.43 (6)
O^v—Ta—Li^ix	112.3 (4)	O^xvi—Li—Nb^xiii	107.8 (11)
Oⁱⁱ—Ta—Li^vii	49.31 (15)	O^xix—Li—Nb^xv	111.2 (13)
Oⁱ—Ta—Li^x	48.5 (7)	O^xix—Li—Nb^xiii	43.2 (7)
Oⁱⁱ—Ta—Li^viii	76.3 (5)	O^xx—Li—Nb^xv	149.6 (2)
O—Ta—Li^vii	119.67 (19)	O^xvi—Li—Nb^xiv	149.6 (2)
Oⁱⁱⁱ—Ta—Li^vii	49.31 (15)	O^xvii—Li—Nb^xv	42.3 (3)
Oⁱ—Ta—Li^vi	103.3 (4)	O^xviii—Li—Nb^xv	84.3 (7)
Li^vii—Ta—Liⁱⁱⁱ	117.8 (6)	O^xv—Li—Nb^xv	38.48 (16)
Li^vi—Ta—Li^ix	165.9 (14)	O^xviii—Li—Nb^xiv	38.48 (16)
Li^vii—Ta—Li^viii	76.2 (8)	O^xvii—Li—Nb^xiv	95.43 (6)
Li^vii—Ta—Li^ix	117.8 (6)	O^xv—Li—Nb^xiv	111.2 (13)
Li^vi—Ta—Liⁱⁱⁱ	71.41 (16)	O^xv—Li—Nb^xiii	43.2 (7)
Li^viii—Ta—Li^vi	114.5 (6)	O^xv—Li—O^xix	72.8 (11)
Li^viii—Ta—Liⁱⁱⁱ	165.9 (14)	O^xvii—Li—O^xvi	111.1 (11)
Li^vii—Ta—Li^x	76.2 (8)	O^xvii—Li—O^xviii	88.6 (5)
Liⁱⁱⁱ—Ta—Li^ix	100.0 (8)	O^xvii—Li—O^xix	150.3 (18)
Li^vii—Ta—Li^vi	76.2 (8)	O^xx—Li—O^xviii	79.8 (5)
Li^viii—Ta—Li^ix	71.41 (16)	O^xx—Li—O^xix	88.6 (5)
Li^x—Ta—Li^ix	71.42 (16)	O^xx—Li—O^xv	150.3 (18)
Li^vi—Ta—Li^x	114.5 (6)	O^xvi—Li—O^xix	79.8 (5)
Li^x—Ta—Liⁱⁱⁱ	71.42 (16)	O^xvii—Li—O^xv	79.8 (5)
Li^viii—Ta—Li^x	114.5 (6)	O^xvi—Li—O^xv	88.6 (5)
Ta—O—Ta^xi	141.37 (11)	O^xx—Li—O^xvi	111.1 (11)
Ta^xi—O—Nb^xi	0.0 (3)	O^xviii—Li—O^xv	72.8 (11)
Ta—O—Nb^xi	141.4	O^xviii—Li—O^xix	72.8 (11)
Ta—O—Li^xii	116.5 (5)	O^xvi—Li—O^xviii	150.3 (18)
Ta^xi—O—Li^vi	87.5 (7)	O^xx—Li—O^xvii	111.1 (11)

Symmetry codes: (i) −x+y, −x, z; (ii) −x+y−1/3, y−2/3, z−1/6; (iii) −y+2/3, −x+1/3, z−1/6; (iv) −y, x−y, z; (v) x−1/3, x−y+1/3, z−1/6; (vi) x+1/3, y+2/3, z−1/3; (vii) −y, −x, z−1/2; (viii) x−2/3, y−1/3, z−1/3; (ix) −y−1/3, −x−2/3, z−1/6; (x) x+1/3, y−1/3, z−1/3; (xi) −y+1/3, −x+2/3, z+1/6; (xii) −y−1/3, −x+1/3, z−1/6; (xiii) −y, −x, z+1/2; (xiv) x+2/3, y+1/3, z+1/3; (xv) x−1/3, y−2/3, z+1/3; (xvi) −x+y−2/3, y−1/3, z+1/6; (xvii) −y+1/3, −x−1/3, z+1/6; (xviii) −y+2/3, x−y+1/3, z+1/3; (xix) −x+y−1/3, −x+1/3, z+1/3; (xx) x+1/3, x−y+2/3, z+1/6.

lithium niobate tantalate (LNT92) top

Crystal data top

LiNb_0.08O₃Ta_0.92	D_x = 7.206 Mg m⁻³
M_r = 228.85	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 1673 reflections
a = 5.149 (1) Å	θ = 5.4–37.2°
c = 13.781 (5) Å	µ = 48.06 mm⁻¹
V = 316.41 (17) Å³	T = 293 K
Z = 6	Block, clear green
F(000) = 585	0.22 × 0.16 × 0.15 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	371 independent reflections
Radiation source: Enhance (Mo) X-ray Source	358 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.045
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.5°, θ_min = 5.5°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.014, T_max = 0.067	l = −22→23
2340 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0313P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.019	(Δ/σ)_max < 0.001
wR(F²) = 0.048	Δρ_max = 2.14 e Å⁻³
S = 1.15	Δρ_min = −1.56 e Å⁻³
371 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
18 parameters	Extinction coefficient: 0.0238 (15)
1 restraint	Absolute structure: Refined as an inversion twin.
Primary atom site location: Other	Absolute structure parameter: 0.48 (13)

Special details top

Refinement. Refined as a 2-component inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ta	0.0000	0.0000	0.0015 (5)	0.00400 (18)	0.92
Nb	0.0000	0.0000	0.0015 (5)	0.00400 (18)	0.08
O	0.0503 (4)	0.3445 (4)	0.0698 (6)	0.0061 (3)
Li	0.0000	0.0000	0.284 (3)	0.009 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.0041 (2)	0.0041 (2)	0.0039 (2)	0.00204 (10)	0.000	0.000
Nb	0.0041 (2)	0.0041 (2)	0.0039 (2)	0.00204 (10)	0.000	0.000
O	0.0067 (9)	0.0048 (6)	0.0072 (5)	0.0032 (9)	−0.0018 (9)	−0.0019 (4)
Li	0.006 (8)	0.006 (8)	0.015 (13)	0.003 (4)	0.000	0.000

Geometric parameters (Å, º) top

Ta—O	1.908 (4)	O—Li^vi	2.28 (3)
Ta—Oⁱ	2.072 (6)	O—Li^xii	2.052 (14)
Ta—Oⁱⁱ	2.072 (6)	Li—Ta^xiii	3.00 (4)
Ta—Oⁱⁱⁱ	1.908 (4)	Li—Ta^xiv	3.056 (10)
Ta—O^iv	1.908 (4)	Li—Ta^xv	3.056 (10)
Ta—O^v	2.072 (6)	Li—Nb^xiv	3.056 (10)
Ta—Li^vi	3.056 (10)	Li—Nb^xiii	3.00 (4)
Ta—Li^vii	3.00 (4)	Li—Nb^xv	3.056 (10)
Ta—Li^viii	3.056 (10)	Li—O^xvi	2.052 (14)
Ta—Li^ix	3.37 (2)	Li—O^xv	2.28 (3)
Ta—Li^x	3.056 (10)	Li—O^xvii	2.052 (14)
Ta—Liⁱⁱ	3.37 (2)	Li—O^xviii	2.28 (3)
O—Ta^xi	2.072 (6)	Li—O^xix	2.28 (3)
O—Nb^xi	2.072 (6)	Li—O^xx	2.052 (14)

O—Ta—O^iv	97.7 (3)	Ta—O—Li^vi	93.4 (7)
O^iv—Ta—Oⁱ	88.87 (6)	Nb^xi—O—Li^vi	87.3 (8)
O—Ta—Oⁱⁱ	88.86 (6)	Li^xii—O—Ta^xi	95.6 (9)
Oⁱ—Ta—Oⁱⁱ	81.9 (3)	Li^xii—O—Nb^xi	95.6 (9)
Oⁱⁱⁱ—Ta—Oⁱ	90.43 (6)	Li^xii—O—Li^vi	120.4 (9)
Oⁱ—Ta—O^v	81.9 (3)	Ta^xiii—Li—Ta^xv	76.6 (8)
O—Ta—Oⁱⁱⁱ	97.7 (3)	Ta^xiv—Li—Ta^xv	114.8 (6)
Oⁱⁱⁱ—Ta—Oⁱⁱ	168.7 (4)	Ta^xiii—Li—Ta^xiv	76.6 (8)
O—Ta—O^v	90.43 (6)	Ta^xiv—Li—Nb^xv	114.8 (6)
O^iv—Ta—O^v	168.7 (4)	Ta^xiii—Li—Nb^xiii	0.0
O^iv—Ta—Oⁱⁱⁱ	97.7 (3)	Ta^xv—Li—Nb^xv	0.0
Oⁱⁱⁱ—Ta—O^v	88.86 (6)	Ta^xiv—Li—Nb^xiv	0.0 (2)
O^iv—Ta—Oⁱⁱ	90.43 (6)	Ta^xiii—Li—Nb^xv	76.6 (8)
O—Ta—Oⁱ	168.7 (4)	Ta^xiii—Li—Nb^xiv	76.6 (8)
Oⁱⁱ—Ta—O^v	81.9 (3)	Nb^xiii—Li—Ta^xiv	76.6
O—Ta—Li^vii	119.6 (2)	Nb^xiv—Li—Ta^xv	114.8
Oⁱⁱ—Ta—Li^ix	147.7 (4)	Nb^xiii—Li—Ta^xv	76.6
Oⁱⁱ—Ta—Liⁱⁱ	72.4 (7)	Nb^xiv—Li—Nb^xv	114.8 (6)
O^iv—Ta—Li^vii	119.6 (2)	Nb^xiii—Li—Nb^xv	76.6 (8)
Oⁱⁱⁱ—Ta—Liⁱⁱ	118.5 (7)	Nb^xiii—Li—Nb^xiv	76.6 (8)
O^v—Ta—Li^x	121.6 (8)	O^xviii—Li—Ta^xiv	38.57 (18)
O^iv—Ta—Li^viii	141.5 (4)	O^xvii—Li—Ta^xv	149.4 (3)
O^v—Ta—Li^vi	76.5 (5)	O^xx—Li—Ta^xv	95.54 (7)
O—Ta—Liⁱⁱ	70.3 (3)	O^xv—Li—Ta^xiv	111.9 (13)
Oⁱⁱ—Ta—Li^viii	121.6 (8)	O^xviii—Li—Ta^xiii	43.6 (8)
O^v—Ta—Li^vii	49.18 (18)	O^xx—Li—Ta^xiii	108.4 (12)
Oⁱⁱⁱ—Ta—Li^x	103.2 (4)	O^xvi—Li—Ta^xv	42.4 (3)
O—Ta—Li^viii	103.2 (4)	O^xix—Li—Ta^xv	111.9 (13)
Oⁱⁱⁱ—Ta—Li^vi	141.5 (4)	O^xvii—Li—Ta^xiv	42.4 (3)
Oⁱⁱ—Ta—Li^x	76.5 (5)	O^xix—Li—Ta^xiii	43.6 (8)
Oⁱ—Ta—Li^vi	121.6 (8)	O^xvii—Li—Ta^xiii	108.4 (12)
Oⁱⁱ—Ta—Li^vi	41.9 (6)	O^xviii—Li—Ta^xv	84.7 (8)
Oⁱⁱⁱ—Ta—Li^ix	32.96 (15)	O^xv—Li—Ta^xv	38.57 (18)
Oⁱⁱⁱ—Ta—Li^viii	48.0 (8)	O^xx—Li—Ta^xiv	149.4 (3)
O^iv—Ta—Liⁱⁱ	32.96 (15)	O^xvi—Li—Ta^xiv	95.54 (7)
O^iv—Ta—Li^vi	103.2 (4)	O^xv—Li—Ta^xiii	43.6 (8)
Oⁱ—Ta—Liⁱⁱ	112.5 (4)	O^xvi—Li—Ta^xiii	108.4 (12)
O^iv—Ta—Li^x	48.0 (8)	O^xix—Li—Ta^xiv	84.7 (8)
O^v—Ta—Liⁱⁱ	147.7 (4)	O^xx—Li—Nb^xiv	149.4 (3)
O^v—Ta—Li^viii	41.9 (6)	O^xviii—Li—Nb^xiii	43.6 (8)
O^iv—Ta—Li^ix	70.3 (3)	O^xx—Li—Nb^xiii	108.4 (12)
Oⁱ—Ta—Li^x	41.9 (6)	O^xvii—Li—Nb^xiii	108.4 (12)
Oⁱ—Ta—Li^ix	72.4 (7)	O^xix—Li—Nb^xiv	84.7 (8)
O—Ta—Li^ix	118.5 (7)	O^xvi—Li—Nb^xv	42.4 (3)
O^v—Ta—Li^ix	112.5 (4)	O^xvi—Li—Nb^xiii	108.4 (12)
Oⁱ—Ta—Li^vii	49.18 (18)	O^xix—Li—Nb^xv	111.9 (13)
O—Ta—Li^x	141.5 (4)	O^xix—Li—Nb^xiii	43.6 (8)
Oⁱ—Ta—Li^viii	76.5 (5)	O^xx—Li—Nb^xv	95.54 (7)
Oⁱⁱⁱ—Ta—Li^vii	119.6 (2)	O^xvi—Li—Nb^xiv	95.54 (7)
Oⁱⁱ—Ta—Li^vii	49.18 (18)	O^xvii—Li—Nb^xv	149.4 (3)
O—Ta—Li^vi	48.0 (8)	O^xviii—Li—Nb^xv	84.7 (8)
Li^vii—Ta—Liⁱⁱ	118.1 (7)	O^xv—Li—Nb^xv	38.57 (18)
Li^vi—Ta—Li^ix	165.2 (15)	O^xviii—Li—Nb^xiv	38.57 (18)
Li^vii—Ta—Li^viii	76.6 (8)	O^xvii—Li—Nb^xiv	42.4 (3)
Li^vii—Ta—Li^ix	118.1 (7)	O^xv—Li—Nb^xiv	111.9 (13)
Li^vi—Ta—Liⁱⁱ	71.34 (18)	O^xv—Li—Nb^xiii	43.6 (8)
Li^viii—Ta—Li^vi	114.8 (6)	O^xv—Li—O^xix	73.3 (12)
Li^viii—Ta—Liⁱⁱ	165.2 (15)	O^xvii—Li—O^xvi	110.5 (12)
Li^vii—Ta—Li^x	76.6 (8)	O^xvii—Li—O^xviii	80.1 (5)
Liⁱⁱ—Ta—Li^ix	99.6 (9)	O^xvii—Li—O^xix	89.0 (6)
Li^vii—Ta—Li^vi	76.6 (8)	O^xx—Li—O^xviii	151.2 (19)
Li^viii—Ta—Li^ix	71.34 (18)	O^xx—Li—O^xix	80.1 (5)
Li^x—Ta—Li^ix	71.35 (18)	O^xx—Li—O^xv	89.0 (6)
Li^vi—Ta—Li^x	114.8 (6)	O^xvi—Li—O^xix	151.2 (19)
Li^x—Ta—Liⁱⁱ	71.35 (18)	O^xvii—Li—O^xv	151.2 (19)
Li^viii—Ta—Li^x	114.8 (6)	O^xvi—Li—O^xv	80.1 (5)
Ta—O—Ta^xi	141.37 (14)	O^xx—Li—O^xvi	110.5 (12)
Ta^xi—O—Nb^xi	0.0 (3)	O^xviii—Li—O^xv	73.3 (12)
Ta—O—Nb^xi	141.4	O^xviii—Li—O^xix	73.3 (12)
Ta—O—Li^xii	116.6 (5)	O^xvi—Li—O^xviii	89.0 (6)
Ta^xi—O—Li^vi	87.3 (8)	O^xx—Li—O^xvii	110.5 (12)

Lithium tantalate (LNT100) top

Crystal data top

LiO₃Ta	D_x = 7.438 Mg m⁻³
M_r = 235.89	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 2836 reflections
a = 5.148 (1) Å	θ = 5.4–37.2°
c = 13.767 (5) Å	µ = 51.84 mm⁻¹
V = 315.97 (17) Å³	T = 293 K
Z = 6	Block, clear green
F(000) = 600	0.29 × 0.23 × 0.20 mm

Data collection top

Xcalibur, Ruby, Gemini diffractometer	374 independent reflections
Radiation source: Enhance (Mo) X-ray Source	369 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.060
Detector resolution: 10.2833 pixels mm^-1	θ_max = 37.5°, θ_min = 5.5°
ω scans	h = −8→8
Absorption correction: analytical CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −8→8
T_min = 0.004, T_max = 0.039	l = −23→23
3971 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: Other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0244P)² + 0.0565P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.017	(Δ/σ)_max < 0.001
wR(F²) = 0.044	Δρ_max = 2.12 e Å⁻³
S = 1.25	Δρ_min = −1.25 e Å⁻³
374 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
18 parameters	Extinction coefficient: 0.0323 (18)
1 restraint	Absolute structure: Refined as an inversion twin.
Primary atom site location: Other	Absolute structure parameter: 0.37 (13)

Special details top

Refinement. Refined as a 2-component inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ta	0.0000	0.0000	0.0013 (6)	0.00433 (16)
O	0.0502 (3)	0.3443 (4)	0.0701 (6)	0.0062 (3)
Li	0.0000	0.0000	0.282 (4)	0.013 (7)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.00448 (18)	0.00448 (18)	0.0040 (2)	0.00224 (9)	0.000	0.000
O	0.0067 (8)	0.0044 (6)	0.0071 (5)	0.0025 (8)	−0.0024 (8)	−0.0018 (4)
Li	0.007 (8)	0.007 (8)	0.027 (18)	0.003 (4)	0.000	0.000

Geometric parameters (Å, º) top

Ta—Oⁱ	1.910 (4)	O—Li^vi	2.29 (4)
Ta—Oⁱⁱ	2.068 (6)	Li—Ta^xi	3.36 (3)
Ta—Oⁱⁱⁱ	2.068 (6)	Li—Ta^xiii	3.02 (5)
Ta—O	1.910 (4)	Li—Ta^xiv	3.058 (13)
Ta—O^iv	1.910 (4)	Li—Ta^xv	3.058 (13)
Ta—O^v	2.068 (6)	Li—Ta^xvi	3.36 (3)
Ta—Li^vi	3.058 (13)	Li—Ta^xvii	3.058 (13)
Ta—Li^vii	3.02 (5)	Li—O^xviii	2.045 (17)
Ta—Li^viii	3.058 (13)	Li—O^xv	2.29 (4)
Ta—Li^ix	3.36 (3)	Li—O^xix	2.29 (4)
Ta—Li^x	3.058 (13)	Li—O^xx	2.045 (17)
Ta—Liⁱⁱⁱ	3.36 (3)	Li—O^xxi	2.045 (17)
O—Ta^xi	2.068 (6)	Li—O^xxii	2.29 (4)
O—Li^xii	2.045 (17)

Oⁱ—Ta—O^iv	97.5 (3)	Ta^xi—O—Li^vi	87.4 (9)
O^iv—Ta—Oⁱⁱ	90.42 (6)	Li^xii—O—Ta^xi	96.1 (11)
Oⁱ—Ta—Oⁱⁱⁱ	90.42 (6)	Li^xii—O—Li^vi	120.0 (11)
Oⁱⁱ—Ta—Oⁱⁱⁱ	82.1 (3)	Ta^xiv—Li—Ta^xvi	165.7 (18)
O—Ta—Oⁱⁱ	169.0 (4)	Ta^xiv—Li—Ta^xi	71.4 (2)
Oⁱⁱ—Ta—O^v	82.1 (3)	Ta^xvii—Li—Ta^xvi	71.4 (2)
Oⁱ—Ta—O	97.5 (3)	Ta^xiii—Li—Ta^xv	76.4 (10)
O—Ta—Oⁱⁱⁱ	88.88 (6)	Ta^xv—Li—Ta^xvii	114.6 (7)
Oⁱ—Ta—O^v	169.0 (4)	Ta^xiii—Li—Ta^xvii	76.4 (10)
O^iv—Ta—O^v	88.88 (6)	Ta^xvii—Li—Ta^xi	71.4 (2)
O^iv—Ta—O	97.5 (3)	Ta^xiv—Li—Ta^xv	114.6 (7)
O—Ta—O^v	90.42 (6)	Ta^xv—Li—Ta^xvi	71.4 (2)
O^iv—Ta—Oⁱⁱⁱ	169.0 (4)	Ta^xvi—Li—Ta^xi	99.9 (10)
Oⁱ—Ta—Oⁱⁱ	88.88 (6)	Ta^xiii—Li—Ta^xiv	76.4 (10)
Oⁱⁱⁱ—Ta—O^v	82.1 (3)	Ta^xiv—Li—Ta^xvii	114.6 (7)
Oⁱ—Ta—Li^vii	119.7 (2)	Ta^xv—Li—Ta^xi	165.7 (18)
Oⁱⁱⁱ—Ta—Li^ix	147.6 (4)	Ta^xiii—Li—Ta^xi	117.9 (8)
Oⁱⁱⁱ—Ta—Liⁱⁱⁱ	72.0 (8)	Ta^xiii—Li—Ta^xvi	117.9 (8)
O^iv—Ta—Li^vii	119.7 (2)	O^xxi—Li—Ta^xv	42.3 (3)
O—Ta—Liⁱⁱⁱ	70.4 (3)	O^xxii—Li—Ta^xvii	111.4 (16)
Oⁱ—Ta—Li^vi	103.3 (5)	O^xviii—Li—Ta^xvii	42.3 (3)
O^iv—Ta—Li^viii	48.4 (9)	O^xviii—Li—Ta^xiii	107.9 (14)
Oⁱ—Ta—Li^x	48.4 (9)	O^xxii—Li—Ta^xiii	43.2 (9)
Oⁱ—Ta—Liⁱⁱⁱ	32.98 (18)	O^xv—Li—Ta^xiv	111.4 (16)
Oⁱⁱⁱ—Ta—Li^viii	121.5 (9)	O^xx—Li—Ta^xvii	95.48 (7)
O^v—Ta—Li^vii	49.33 (18)	O^xxii—Li—Ta^xv	84.4 (9)
O—Ta—Li^x	141.6 (5)	O^xxi—Li—Ta^xi	126.5 (19)
Oⁱ—Ta—Li^viii	141.6 (5)	O^xix—Li—Ta^xvi	105.9 (2)
O—Ta—Li^vi	48.4 (9)	O^xv—Li—Ta^xi	153.6 (12)
Oⁱⁱⁱ—Ta—Li^x	76.4 (6)	O^xx—Li—Ta^xiii	107.9 (14)
Oⁱⁱ—Ta—Li^vi	121.5 (9)	O^xix—Li—Ta^xiv	84.4 (9)
O^v—Ta—Li^vi	76.4 (6)	O^xxii—Li—Ta^xi	105.9 (2)
O—Ta—Li^ix	118.6 (8)	O^xviii—Li—Ta^xv	95.48 (7)
O—Ta—Li^viii	103.3 (5)	O^xix—Li—Ta^xv	111.4 (16)
O^iv—Ta—Liⁱⁱⁱ	118.6 (8)	O^xxii—Li—Ta^xvi	153.6 (12)
O^iv—Ta—Li^vi	141.6 (5)	O^xv—Li—Ta^xvii	84.4 (9)
Oⁱⁱ—Ta—Liⁱⁱⁱ	112.3 (5)	O^xv—Li—Ta^xvi	81.58 (13)
O^iv—Ta—Li^x	103.3 (5)	O^xix—Li—Ta^xvii	38.6 (2)
O^v—Ta—Liⁱⁱⁱ	147.6 (4)	O^xxi—Li—Ta^xvii	149.5 (3)
O^v—Ta—Li^viii	41.7 (7)	O^xv—Li—Ta^xiii	43.2 (9)
O^iv—Ta—Li^ix	32.98 (18)	O^xx—Li—Ta^xi	30.6 (4)
O—Ta—Li^vii	119.7 (2)	O^xix—Li—Ta^xiii	43.2 (9)
Oⁱⁱ—Ta—Li^ix	72.0 (8)	O^xx—Li—Ta^xiv	42.3 (3)
Oⁱ—Ta—Li^ix	70.4 (3)	O^xviii—Li—Ta^xiv	149.5 (3)
O^v—Ta—Li^ix	112.3 (5)	O^xxi—Li—Ta^xiv	95.48 (7)
Oⁱⁱ—Ta—Li^vii	49.33 (18)	O^xviii—Li—Ta^xvi	30.6 (4)
Oⁱⁱⁱ—Ta—Li^vi	41.7 (7)	O^xxii—Li—Ta^xiv	38.6 (2)
Oⁱⁱ—Ta—Li^viii	76.4 (6)	O^xx—Li—Ta^xvi	126.5 (19)
Oⁱⁱ—Ta—Li^x	41.7 (7)	O^xix—Li—Ta^xi	81.58 (13)
Oⁱⁱⁱ—Ta—Li^vii	49.33 (18)	O^xv—Li—Ta^xv	38.6 (2)
O^v—Ta—Li^x	121.5 (9)	O^xviii—Li—Ta^xi	80.5 (9)
Li^viii—Ta—Liⁱⁱⁱ	165.7 (18)	O^xx—Li—Ta^xv	149.5 (3)
Li^viii—Ta—Li^ix	71.4 (2)	O^xxi—Li—Ta^xiii	107.9 (14)
Li^viii—Ta—Li^x	114.6 (7)	O^xxi—Li—Ta^xvi	80.5 (9)
Li^vii—Ta—Li^viii	76.4 (10)	O^xviii—Li—O^xv	88.7 (7)
Li^x—Ta—Liⁱⁱⁱ	71.4 (2)	O^xviii—Li—O^xix	79.8 (6)
Li^vii—Ta—Li^x	76.4 (10)	O^xxi—Li—O^xix	150 (2)
Li^vi—Ta—Liⁱⁱⁱ	71.4 (2)	O^xviii—Li—O^xx	111.0 (13)
Li^vi—Ta—Li^x	114.6 (7)	O^xx—Li—O^xix	88.7 (7)
Li^vii—Ta—Liⁱⁱⁱ	117.9 (8)	O^xx—Li—O^xxii	79.8 (6)
Li^viii—Ta—Li^vi	114.6 (7)	O^xxii—Li—O^xv	72.8 (14)
Li^vii—Ta—Li^vi	76.4 (10)	O^xv—Li—O^xix	72.8 (14)
Li^x—Ta—Li^ix	71.4 (2)	O^xviii—Li—O^xxi	111.0 (13)
Li^vii—Ta—Li^ix	117.9 (8)	O^xx—Li—O^xxi	111.0 (13)
Liⁱⁱⁱ—Ta—Li^ix	99.9 (10)	O^xxi—Li—O^xv	79.8 (6)
Li^vi—Ta—Li^ix	165.7 (18)	O^xviii—Li—O^xxii	150 (2)
Ta—O—Ta^xi	141.43 (13)	O^xxi—Li—O^xxii	88.7 (7)
Ta—O—Li^xii	116.5 (6)	O^xxii—Li—O^xix	72.8 (14)
Ta—O—Li^vi	93.1 (8)	O^xx—Li—O^xv	150 (2)

Symmetry codes: (i) −x+y, −x, z; (ii) −x+y−1/3, y−2/3, z−1/6; (iii) −y+2/3, −x+1/3, z−1/6; (iv) −y, x−y, z; (v) x−1/3, x−y+1/3, z−1/6; (vi) x+1/3, y+2/3, z−1/3; (vii) −y, −x, z−1/2; (viii) x−2/3, y−1/3, z−1/3; (ix) −y−1/3, −x−2/3, z−1/6; (x) x+1/3, y−1/3, z−1/3; (xi) −y+1/3, −x+2/3, z+1/6; (xii) −y−1/3, −x+1/3, z−1/6; (xiii) −y, −x, z+1/2; (xiv) x+2/3, y+1/3, z+1/3; (xv) x−1/3, y−2/3, z+1/3; (xvi) −y−2/3, −x−1/3, z+1/6; (xvii) x−1/3, y+1/3, z+1/3; (xviii) −x+y−2/3, y−1/3, z+1/6; (xix) −x+y−1/3, −x+1/3, z+1/3; (xx) x+1/3, x−y+2/3, z+1/6; (xxi) −y+1/3, −x−1/3, z+1/6; (xxii) −y+2/3, x−y+1/3, z+1/3.

Acknowledgements

The PANalytical MPD diffractometer used in this research was obtained through the Science City Energy Futures Project: Hydrogen Energy, with support from Advantage West Midlands (AWM). The Oxford Diffraction Gemini CCD and Panalytical MRD diffractometers used in this research were obtained through the Science City Advanced Materials Project: Creating and Characterizing Next Generation Advanced Materials, with support from AWM and part funded by the European Regional Development Fund (ERDF).

Funding information

Funding for this research was provided by: Engineering and Physical Sciences Research Council (award No. EP/F042787/1); Labex ACTION program (award No. ANR-11-LABX-0001-01).

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Volume 73| Part 3| June 2017| Pages 498-506

https://doi.org/10.1107/S2052520617004711

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