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Single-crystal synchrotron X-ray diffraction reveals partial structural disorder of Tb atoms at 293 K in flux-grown Tb3RuO7 (triterbium ruthenium hepta­oxide) crystals. The structure is noncentrosymmetric and composed of infinite single chains of corner-linked RuO6 octa­hedra embedded in a Tb3O matrix. Two Tb atom sites out of the six crystallographically independent Tb sites are split into two positions. The split sites are separated by approximately 0.3-0.4 Å, with slightly different coordination environments. The RuO6 octa­hedra in the present P21nb modification have two tilt systems about the a and c axes, in contrast with a single tilt about c in the other Cmcm modifications of Ln3RuO7 (Ln = lanthanoid elements).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107021993/sq3070sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107021993/sq3070Isup2.hkl
Contains datablock I

Comment top

The series of Ln3MO7 crystals composed of trivalent lanthanide (Ln) and pentavalent transition metal (M = Ru or Os) oxides is known to form Cmcm and P21nb modifications. The latter is noncentrosymmetric, with a doubled b length compared with the centrosymmetric Cmcm structure. The two modifications are related by a phase transition, with transition temperatures of 190 K for Sm3RuO7, 280 K for Eu3RuO7, 235 K for Sm3OsO7, 330 K for Eu3OsO7 and 430 K for Gd3OsO7 (Gemmill et al., 2004, 2005). The P21nb modification of Gd3RuO7 (Ishizawa et al., 2006) shows a curious structural feature: two Gd atom sites out of the six crystallographically independent positions have relatively large atomic displacement ellipsoids prolate along b. The present paper focuses on Tb3RuO7, which has been identified as a new member of the Ln3RuO7 structural family for the first time, and deals with the partial structural disorder found in the P21nb modification using single-crystal synchrotron X-ray diffraction data collected with a relatively high resolution of d > 0.42 Å.

The structure of Tb3RuO7 is composed of infinite [RuO5] single chains of corner-linked [RuO6] octahedra embedded in a matrix of Ln and O atoms, as shown in Fig. 1. There are two crystallographically independent octahedra, [Ru1O6] and [Ru2O6], alternately repeated along the chain. The [Ru1O6] octahedron accommodates two tilt systems of approximately 11° about the c axis and 19° about the a axis. Although the [Ru2O6] octahedron is allowed by symmetry to have two tilt systems similar to [Ru1O6], the tilt about c is negligibly small and it can be considered as having practically only one tilt system of 19° about a.

The Ru—O bond distances range from 1.907 (4) to 1.985 (3) Å for Ru1, and from 1.926 (3) to 1.970 (3) Å for Ru2. The mean Ru—O distance is 1.944 Å, which is slightly shorter than that of 1.951 Å in Gd3RuO7 (Ishizawa et al., 2006).

Due to the octahedral tilts, the Ru–O–Ru angles along the chain direction differ markedly from 180°, being 140.8 (2)° for Ru1–O1–Ru2 and 142.3 (2)° for Ru1–O2–Ru2, with a mean value 0.6° smaller than for Gd3RuO7. The decrease of Ru–O–Ru angle along the chain provides a closer Ru···Ru intermetallic distance of 3.665 Å. The Ln3MO7 structural family is known to possess quasi one-dimensional conduction along the [RuO5] single chains. The conductivity is believed to increase with decreasing Ru···Ru intermetallic distance. For example, the resistivity at room temperature, the mean Ru···Ru distance and the mean Ru—O—Ru angle for Eu3RuO7 are 170 Ω cm (Harada & Hinatsu, 2001), 3.706 Å and 143.9°, respectively (Gemmill et al., 2004), while those for Gd3RuO7 are 2 Ω cm (Bontchev et al., 2000), 3.692 Å and 142.2°, respectively (Ishizawa et al., 2006). If this is the case in all Ln3RuO7, an enhanced conductivity is expected for Tb3RuO7 compared with Gd3RuO7.

As described in the refinement section, the Tb5 and Tb6 atom sites in the non-split atom model have relatively large atomic displacement ellipsoids prolate along b compared with the other four Tb atoms. The structure can be best described by assuming a split-atom model for these Tb sites (i.e. Tb5a and Tb5b instead of Tb5, and Tb6a and Tb6b instead of Tb6), as shown in Fig. 2. The distance between Tb5a and Tb5b is 0.322 (5) Å and that between Tb6a and Tb6b is 0.390 (5) Å. These large separation distances indicate that the split-atom model is preferable to the anharmonic vibration model.

The population and coordination numbers differ slightly between these sites. Sites Tb5a and Tb6a are populated with 91.5 (3)% and 94.4 (2)% Tb atoms, respectively, and are coordinated by seven O atoms in the range 2.268 (4)–2.556 (3) Å with a mean of 2.40 Å. The next longer Tb–O distances for these Tb atoms exceed 3.30 Å and can be excluded from the coordination polyhedron. On the other hand, sites Tb5b and Tb6b are much less populated, with 8.5 (3)% and 5.6 (2)% occupation by Tb atoms, respectively. They are surrounded by five O atoms in the range 2.197 (6)–2.459 (5) Å with a mean of 2.30 Å. There are three additional O atoms in the range 2.736 (6)–3.019 (6) Å. Thus, the b sites of atoms Tb5 and Tb6 are considered to have fivefold coordination or perhaps 5 + 3 coordination. This complicated geometry contrasts with the rather simple coordination of atoms Tb1–Tb4, which are distinctly sevenfold, with the mean Tb–O distances falling in a relatively small range between 2.34 and 2.37 Å. No such disorder was found around the periphery of these Tb atom sites.

We currently have no clear explanation as to why this partial structural disorder occurs at the Tb5 and Tb6 sites. We note, however, two peculiarities associated with these sites. One is that these sites play an important role in the phase transition between Cmcm and P21nb. There are two crystallographically independent Ln sites in the Cmcm modification, i.e. Ln1 corresponding to Ln1–4 in P21nb, and Ln2 corresponding to Ln5–6 in P21nb. The Ln1 site (Cmcm) has sevenfold coordination and has little effect on the transition. On the other hand, the Ln2 site (Cmcm) has eightfold coordination, and differentiates into sites Ln5 and Ln6 in P21nb with sevenfold coordination on the transition. The reduction in coordination is geometrically associated with tilts about c for half of the RuO6 octahedra. The second peculiarity is the systematic difference between Tb1–4 and Tb5–6 in the bond-valence sums (BVS; Standard reference?), as given in Table 1. The mean BVS of sites Tb1–Tb4 are 3.18 (11), larger than the value of 3 that is expected from the formal oxidation state. On the other hand, they show smaller mean values of 2.82 (6) for sites Tb5a and Tb6a, and 2.97 (3) for sites Tb5b and Tb6b.

It would be interesting to determine whether such partial disorder at sites Ln5 and Ln6 is common in all P21nb modifications of the Ln3MO7 family. Large prolate atomic displacement parameters for Gd1 and Gd2 have been reported in Gd3RuO7 (Ishizawa et al., 2006). On the other hand, such a tendency in Ln3RuO7 (Ln = Eu and Sm) is less apparent (Gemmel, 2004, 2005; Should these be Gemmill et al., 2004, 2005?). It is worth mentioning that such disorder is easily obscured when the resolution of the measurement is reduced. The effect of the resolution level on the results of the refinement has been simulated using the present dataset and is shown in Table 2. The residual electrons around Tb5 and Tb6 decrease from 34 e Å-3 (d > 0.42 Å) to a negligibly small value of 1 e Å-3 (d > 1.01 Å) as a function of resolution. Although the prolate feature of the atomic displacement parameters still flags potentially serious problems underlying these sites in all data sets, it is difficult to refine the disordered positions from data taken at low resolutions. The resolution should be better than 0.54 Å to distinguish the split-atom model from the single-atom model at a reasonable level of significance.

Related literature top

For related literature, see: Bontchev et al. (2000); Gemmill et al. (2004, 2005); Hall et al. (2003); Harada & Hinatsu (2001); Ishizawa et al. (2006); Kishimoto et al. (1998); Sasaki (1989, 1990).

Experimental top

Reagent grade powders (Kojundo Chemical Laboratory Co. Ltd.) of Tb4O7 (99.9% purity), RuO2 (99.9% purity) and SrCl2 (99% purity) were mixed together in a molar ratio of 7.5:10:90 in a 25 ml platinum crucible and heated at 1373 K in air for 10 h. The sample was then cooled at 5 K h-1 to 973 K, followed by a discharge in ambient conditions. The sample batch was washed in warm water to dissolve the flux. Black crystals smaller than 0.1 mm in length were found. Most crystals have a columnar shape surrounded by well developed {120} side planes and capped by {101}. EDS [Energy-dispersive spectometry?] analysis identified the existence of the elements Tb, Ru and O in the crystal, indicating no contamination from the SrCl2 flux within experimental error.

Refinement top

Single-crystal diffraction data were collected using the horizontal-type high-speed four-circle diffractometer at beamline 14 A of the Photon Factory, Tsukuba. X-rays of 0.6886 (1) Å were focused through a pinhole 0.4 mm in diameter on the sample using an Si(111) double-crystal monochromator and a Pt-coated toroidal mirror. The wavelength was calibrated by a spherical Si standard crystal 75 µ [Please give correct units] in diameter. Dispersion and absorption coefficients at this wavelength were taken from tables given by Sasaki (1989, 1990). An eight-channel avalanche photodiode detector was used for photon counting (Kishimoto et al., 1998). Since the detector has a counting linearity above 109 counts per s, neither absorbers nor attenuators were employed. The Xtal3.7 program package was used for further calculations (Hall et al., 2003).

The least-squares refinement applying anisotropic atomic displacement parameters for all fully populated atom sites yielded R/Rw factors of 0.027/0.039 for 7216 reflections. However, large residual electron-density peaks of 33–34 e Å-3 were found about 0.42 Å away from both Tb5 and Tb6 in the difference Fourier map after the refinement. Further refinement to examine the population of Tb and Ru atom sites did not significantly affect the R/Rw factors or the residual electron-density peaks. The deviation of the populations from 100% was marginal. A split-atom model for Tb5 into Tb5a and Ta5b, and for Tb6 into Tb6a and Tb6b, was then undertaken. The refinement decreased the R/Rw factors to 0.017/0.027 for 7216 independent reflections and 208 parameters. Thus, this model was adopted according to Hamilton's significance test [Reference needed?]. The residual electron density near Tb5 and Tb6 decreased to less than 3.5 e Å-3. The refined Flack parameter of nearly 50% suggested the presence of very fine micro-twins related by an inversion operation, as is common for most P21nb modifications of Ln3RuO7 and Ln3OsO7. These twins were supposedly introduced by the phase transition from the centrosymmetric base-centred lattice to the noncentrosymmetric primitive lattice with doubled cell volume, allowing the generation of eight possible variants at room temperature.

The refinement with anisotropic atomic displacement parameters for all atoms revealed a prolate feature for O14. The isotropic atomic displacement parameter of O14 was normal compared with the other O atoms. No significant residual electrons were found near O14 before or after refinement assuming anisotropic atomic displacement parameters. Therefore, the prolate feature of O14 could be an artifact that occurred during the least-squares procedure.

Computing details top

Data collection: BL14A diffractometer control software (Satow et al., 2005); cell refinement: LATCON in Xtal3.7 (Hall et al., 2003); data reduction: DIFDAT, ABSORB, SORTRF and ADDREF, all in Xtal3.7; program(s) used to solve structure: Xtal3.7; program(s) used to refine structure: CRYLSQ in Xtal3.7; molecular graphics: ATOMS (Dowty, 2005); software used to prepare material for publication: BONDLA and CIFIO, both in Xtal3.7.

Figures top
[Figure 1] Fig. 1. The structure of Tb3RuO7, featuring RuO6 octahedral chains in the Tb (dark grey) and O (light grey) matrix. Displacement ellipsoids are drawn at the 97% probability level (non-spilt atom model).
[Figure 2] Fig. 2. Geometric relation between the octahedral tilt about c and the interatomic bonds of disordered Tb atoms. The seven bonds around the a site populated by most Tb atoms are drawn with thick lines. The five short bonds and additional two long bonds around the b site populated by trace amounts of Tb atoms are drawn by thin and dashed lines, respectively.
triterbium rubidium heptaoxide top
Crystal data top
Tb3RuO7F(000) = 2360
Mr = 689.86Dx = 8.096 Mg m3
Orthorhombic, P21nbSynchrotron radiation, λ = 0.6886 Å
Hall symbol: p -2bc 21Cell parameters from 12 reflections
a = 10.5672 (3) Åθ = 23–29°
b = 14.5838 (3) ŵ = 34.94 mm1
c = 7.3453 (3) ÅT = 293 K
V = 1131.98 (6) Å3, black
Z = 80.05 × 0.02 × 0.02 mm
Data collection top
Tsukuba
diffractometer
Rint = 0.017
BL14A four–circle diffractometer scansθmax = 55.0°, θmin = 2.7°
Absorption correction: numerical
(ABSORB in Xtal3.7; Hall et al., 2003)
h = 2525
Tmin = 0.320, Tmax = 0.546k = 3434
35935 measured reflectionsl = 717
17021 independent reflections6 standard reflections every 200 reflections reflections
14382 reflections with F2 > 3σ(F2) intensity decay: corrected by Xtal3.7 (Hall et al., 2003)
Refinement top
Refinement on F w = 1/[σ2(Fo) + 0.1(Fo)]
Least-squares matrix: full(Δ/σ)max = 0.037
R[F2 > 2σ(F2)] = 0.018Δρmax = 3.39 e Å3
wR(F2) = 0.027Δρmin = 2.68 e Å3
S = 1.17Extinction correction: Becker-Coppens
7216 reflectionsExtinction coefficient: 2323 (47)
208 parametersAbsolute structure: Flack (1983), with how many Friedel pairs?
0 restraintsAbsolute structure parameter: 0.486 (11)
0 constraints
Crystal data top
Tb3RuO7V = 1131.98 (6) Å3
Mr = 689.86Z = 8
Orthorhombic, P21nbSynchrotron radiation, λ = 0.6886 Å
a = 10.5672 (3) ŵ = 34.94 mm1
b = 14.5838 (3) ÅT = 293 K
c = 7.3453 (3) Å0.05 × 0.02 × 0.02 mm
Data collection top
Tsukuba
diffractometer
14382 reflections with F2 > 3σ(F2)
Absorption correction: numerical
(ABSORB in Xtal3.7; Hall et al., 2003)
Rint = 0.017
Tmin = 0.320, Tmax = 0.5466 standard reflections every 200 reflections reflections
35935 measured reflections intensity decay: corrected by Xtal3.7 (Hall et al., 2003)
17021 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0180 restraints
wR(F2) = 0.027Δρmax = 3.39 e Å3
S = 1.17Δρmin = 2.68 e Å3
7216 reflectionsAbsolute structure: Flack (1983), with how many Friedel pairs?
208 parametersAbsolute structure parameter: 0.486 (11)
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Tb10.22146 (5)0.022930 (15)0.23706 (2)0.00512 (5)
Tb20.23186 (5)0.222404 (15)0.246157 (17)0.00498 (6)
Tb30.28227 (5)0.273682 (15)0.256482 (18)0.00492 (5)
Tb40.27125 (5)0.028037 (15)0.251001 (18)0.00456 (6)
Tb5a0.00535 (6)0.38745 (3)0.00259 (3)0.00551 (6)0.915 (3)
Tb5b0.0028 (3)0.3657 (3)0.0016 (3)0.00551 (6)0.085 (3)
Tb6a0.00938 (6)0.36298 (2)0.49776 (2)0.00561 (5)0.9441 (15)
Tb6b0.0065 (4)0.3868 (4)0.5030 (4)0.00561 (5)0.0559 (15)
Ru10.000000.12616 (3)0.00175 (5)0.00322 (5)
Ru20.00160 (3)0.12495 (3)0.50147 (5)0.00323 (5)
O10.0066 (4)0.0811 (2)0.2511 (2)0.0054 (9)
O20.0094 (6)0.1681 (3)0.2485 (3)0.0091 (12)
O30.1223 (3)0.2201 (2)0.4652 (4)0.0077 (8)
O40.3669 (4)0.1066 (3)0.2357 (4)0.0075 (8)
O50.1257 (3)0.0323 (2)0.5423 (3)0.0082 (8)
O60.1303 (4)0.3825 (3)0.2365 (4)0.0078 (9)
O70.1328 (3)0.2189 (2)0.4627 (3)0.0071 (7)
O80.1346 (4)0.1442 (2)0.2621 (4)0.0064 (8)
O90.1305 (3)0.0316 (2)0.5345 (4)0.0081 (8)
O100.3693 (4)0.1309 (2)0.2432 (3)0.0057 (8)
O110.1053 (3)0.0155 (2)0.0412 (4)0.0091 (9)
O120.1043 (3)0.2357 (2)0.0408 (4)0.0101 (9)
O130.1549 (3)0.0605 (3)0.0423 (4)0.0129 (10)
O140.1516 (4)0.1931 (3)0.0483 (4)0.0176 (13)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Tb10.00448 (6)0.00553 (5)0.00536 (3)0.00070 (5)0.00033 (5)0.00092 (3)
Tb20.00523 (9)0.00496 (6)0.00476 (4)0.00127 (6)0.00004 (3)0.00008 (3)
Tb30.00460 (7)0.00511 (5)0.00504 (4)0.00034 (4)0.00087 (4)0.00032 (3)
Tb40.00436 (8)0.00439 (6)0.00492 (4)0.00006 (6)0.00055 (3)0.00026 (3)
Tb5a0.00439 (5)0.00847 (9)0.00368 (4)0.00048 (5)0.00016 (3)0.00048 (5)
Tb5b0.00439 (5)0.00847 (9)0.00368 (4)0.00048 (5)0.00016 (3)0.00048 (5)
Tb6a0.00499 (5)0.00805 (6)0.00379 (4)0.00041 (4)0.00011 (3)0.00056 (4)
Tb6b0.00499 (5)0.00805 (6)0.00379 (4)0.00041 (4)0.00011 (3)0.00056 (4)
Ru10.00288 (6)0.00408 (5)0.00270 (5)0.00023 (6)0.00009 (3)0.00005 (4)
Ru20.00330 (6)0.00369 (5)0.00270 (5)0.00011 (6)0.00017 (3)0.00023 (4)
O10.0049 (9)0.0096 (12)0.0016 (6)0.0004 (8)0.0006 (4)0.0001 (4)
O20.0156 (16)0.0074 (12)0.0042 (7)0.0013 (11)0.0007 (6)0.0001 (4)
O30.0087 (8)0.0084 (8)0.0059 (6)0.0031 (6)0.0003 (6)0.0010 (6)
O40.0056 (9)0.0080 (9)0.0088 (7)0.0025 (7)0.0016 (6)0.0023 (6)
O50.0085 (8)0.0096 (8)0.0065 (7)0.0036 (7)0.0001 (6)0.0011 (6)
O60.0074 (10)0.0083 (10)0.0078 (7)0.0004 (8)0.0036 (6)0.0019 (6)
O70.0052 (7)0.0097 (8)0.0064 (7)0.0029 (6)0.0017 (5)0.0008 (6)
O80.0070 (9)0.0040 (8)0.0082 (7)0.0023 (6)0.0021 (6)0.0011 (5)
O90.0069 (8)0.0107 (9)0.0067 (7)0.0047 (7)0.0010 (6)0.0000 (6)
O100.0039 (8)0.0049 (8)0.0082 (7)0.0008 (6)0.0014 (5)0.0001 (5)
O110.0126 (11)0.0084 (8)0.0063 (7)0.0051 (7)0.0005 (7)0.0011 (6)
O120.0116 (10)0.0113 (9)0.0073 (7)0.0049 (8)0.0009 (7)0.0001 (7)
O130.0090 (9)0.0221 (14)0.0077 (8)0.0077 (9)0.0007 (6)0.0029 (8)
O140.0148 (11)0.0317 (19)0.0063 (8)0.0179 (13)0.0017 (7)0.0042 (10)
Geometric parameters (Å, º) top
Tb1—O102.219 (4)Tb5a—O9x2.556 (3)
Tb1—O6i2.271 (4)Tb5b—O122.197 (6)
Tb1—O13ii2.288 (3)Tb5b—O62.239 (4)
Tb1—O112.387 (3)Tb5b—O8iv2.286 (4)
Tb1—O92.390 (3)Tb5b—O10viii2.330 (4)
Tb1—O5iii2.426 (3)Tb5b—O4ix2.405 (4)
Tb1—O12.557 (5)Tb5b—O5x2.774 (5)
Tb1—O142.938 (4)Tb5b—O9x2.812 (5)
Tb2—O8iv2.201 (4)Tb5b—O143.019 (6)
Tb2—O42.212 (4)Tb6a—O62.323 (4)
Tb2—O3v2.342 (3)Tb6a—O4ix2.325 (4)
Tb2—O142.362 (3)Tb6a—O10ix2.334 (3)
Tb2—O7vi2.381 (3)Tb6a—O8x2.352 (3)
Tb2—O12v2.412 (3)Tb6a—O11x2.465 (3)
Tb2—O22.480 (7)Tb6a—O72.486 (3)
Tb2—Ru13.3599 (5)Tb6a—O32.517 (3)
Tb3—O62.263 (4)Tb6b—O4ix2.208 (5)
Tb3—O102.279 (4)Tb6b—O10ix2.214 (5)
Tb3—O72.330 (3)Tb6b—O11x2.235 (6)
Tb3—O3v2.367 (3)Tb6b—O62.434 (5)
Tb3—O142.372 (4)Tb6b—O8x2.459 (5)
Tb3—O12vii2.411 (3)Tb6b—O32.736 (6)
Tb3—O2vii2.547 (7)Tb6b—O72.872 (6)
Tb3—O13vii2.911 (4)Tb6b—O13x2.993 (6)
Tb4—O42.212 (4)Ru1—O141.907 (4)
Tb4—O82.228 (4)Ru1—O131.924 (3)
Tb4—O9vi2.335 (3)Ru1—O21.939 (2)
Tb4—O13ii2.340 (3)Ru1—O11.948 (2)
Tb4—O5ii2.401 (3)Ru1—O121.962 (3)
Tb4—O112.420 (3)Ru1—O111.985 (3)
Tb4—O1ii2.472 (5)Ru2—O31.926 (3)
Tb5a—O62.268 (4)Ru2—O51.930 (3)
Tb5a—O10viii2.304 (3)Ru2—O91.941 (3)
Tb5a—O8iv2.321 (3)Ru2—O2xi1.943 (2)
Tb5a—O4ix2.382 (3)Ru2—O11.949 (2)
Tb5a—O122.468 (3)Ru2—O71.970 (3)
Tb5a—O5x2.483 (3)
O14—Ru1—O13178.79 (16)O3—Ru2—O9178.18 (13)
O14—Ru1—O288.0 (2)O3—Ru2—O2xi85.79 (18)
O14—Ru1—O191.98 (16)O3—Ru2—O194.35 (14)
O14—Ru1—O1291.64 (17)O3—Ru2—O787.57 (13)
O14—Ru1—O1188.52 (17)O5—Ru2—O988.77 (13)
O13—Ru1—O292.4 (2)O5—Ru2—O2xi96.29 (18)
O13—Ru1—O187.68 (16)O5—Ru2—O183.43 (14)
O13—Ru1—O1287.25 (15)O5—Ru2—O7179.22 (11)
O13—Ru1—O1192.59 (15)O9—Ru2—O2xi94.54 (18)
O2—Ru1—O1178.38 (18)O9—Ru2—O185.33 (15)
O2—Ru1—O1284.87 (17)O9—Ru2—O790.69 (13)
O2—Ru1—O1194.41 (17)O2xi—Ru2—O1179.69 (14)
O1—Ru1—O1296.75 (14)O2xi—Ru2—O783.19 (18)
O1—Ru1—O1183.97 (14)O1—Ru2—O797.09 (14)
O12—Ru1—O11179.25 (12)Ru1—O1—Ru2140.8 (2)
O3—Ru2—O592.98 (13)Ru1—O2—Ru2vi142.3 (2)
Symmetry codes: (i) x, y1/2, z1/2; (ii) x1/2, y, z; (iii) x1/2, y, z1; (iv) x, y+1/2, z+1/2; (v) x1/2, y+1/2, z+1/2; (vi) x, y, z+1; (vii) x1/2, y+1/2, z1/2; (viii) x+1/2, y+1/2, z+1/2; (ix) x+1/2, y+1/2, z1/2; (x) x, y+1/2, z1/2; (xi) x, y, z1.

Experimental details

Crystal data
Chemical formulaTb3RuO7
Mr689.86
Crystal system, space groupOrthorhombic, P21nb
Temperature (K)293
a, b, c (Å)10.5672 (3), 14.5838 (3), 7.3453 (3)
V3)1131.98 (6)
Z8
Radiation typeSynchrotron, λ = 0.6886 Å
µ (mm1)34.94
Crystal size (mm)0.05 × 0.02 × 0.02
Data collection
DiffractometerTsukuba
diffractometer
Absorption correctionNumerical
(ABSORB in Xtal3.7; Hall et al., 2003)
Tmin, Tmax0.320, 0.546
No. of measured, independent and
observed [F2 > 3σ(F2)] reflections
35935, 17021, 14382
Rint0.017
(sin θ/λ)max1)1.189
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.027, 1.17
No. of reflections7216
No. of parameters208
Δρmax, Δρmin (e Å3)3.39, 2.68
Absolute structureFlack (1983), with how many Friedel pairs?
Absolute structure parameter0.486 (11)

Computer programs: BL14A diffractometer control software (Satow et al., 2005), LATCON in Xtal3.7 (Hall et al., 2003), DIFDAT, ABSORB, SORTRF and ADDREF, all in Xtal3.7, CRYLSQ in Xtal3.7, ATOMS (Dowty, 2005), BONDLA and CIFIO, both in Xtal3.7.

Selected geometric parameters (Å, º) top
Tb5a—O62.268 (4)Tb6a—O62.323 (4)
Tb5a—O10i2.304 (3)Tb6a—O4iii2.325 (4)
Tb5a—O8ii2.321 (3)Tb6a—O10iii2.334 (3)
Tb5a—O4iii2.382 (3)Tb6a—O8iv2.352 (3)
Tb5a—O122.468 (3)Tb6a—O11iv2.465 (3)
Tb5a—O5iv2.483 (3)Tb6a—O72.486 (3)
Tb5a—O9iv2.556 (3)Tb6a—O32.517 (3)
Tb5b—O122.197 (6)Tb6b—O4iii2.208 (5)
Tb5b—O62.239 (4)Tb6b—O10iii2.214 (5)
Tb5b—O8ii2.286 (4)Tb6b—O11iv2.235 (6)
Tb5b—O10i2.330 (4)Tb6b—O62.434 (5)
Tb5b—O4iii2.405 (4)Tb6b—O8iv2.459 (5)
Tb5b—O5iv2.774 (5)Tb6b—O32.736 (6)
Tb5b—O9iv2.812 (5)Tb6b—O72.872 (6)
Tb5b—O143.019 (6)Tb6b—O13iv2.993 (6)
Ru1—O1—Ru2140.8 (2)Ru1—O2—Ru2v142.3 (2)
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x, y+1/2, z+1/2; (iii) x+1/2, y+1/2, z1/2; (iv) x, y+1/2, z1/2; (v) x, y, z+1.
Bond-valence sums (BVS) for Tb3RuO7 top
AtomBVSAtomBVS
Tb13.12Tb5b2.99
Tb23.29Tb6a2.78
Tb33.05Tb6b2.95
Tb43.25Ru15.34
Tb5a2.86Ru25.34
Effects of the resolution level on the results of the refinement. Isotropic atomic displacement parameters for O atoms are assumed in all calculations top
d (Å)sinθ/λ2θ (°)NRnΔρnPnRsΔρsPs
0.421.19011072160.03034 / 333.10.0206.12.3
0.451.11310059820.02827 / 263.20.0195.42.3
0.491.0279047710.02620 / 193.40.0184.52.4
0.540.9348036400.02515 / 144.00.0173.92.6
0.600.8337026230.0229 / 94.90.0173.02.5
0.690.7266017580.0205 / 55.20.0162.02.8
0.810.6145010690.0172 / 25.00.023*6.6a4.7a
1.010.497405880.0171 / 16.90.017*1.2a3.5a
d is the resolution level (Å) used in the refinement. N is the number of independent reflections used. Rn is the R factor of the non-split model using 133 parameters. Δρn is the Δρ (e Å-3) near the Tb5 and Tb6 sites of the non-split model. Pn is the maximum prolate ratio of atomic displacement ellipsoids of Tb5/Tb6 (non-split model). Rs is the R factor of the split model using 144 parameters. Δρs is the Δρ (e Å-3) near Tb5/Tb6 of the split model. Ps is the maximum prolate ratio of atomic displacement ellipsoids of Tb5 and Tb6 (split-atom model). a The refinement is unstable.
 

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