The γ-phase of SrTeO₃ at 583 K

As a part of current systematic investigations of strontium tellurite, SrTeO₃, with particular emphasis on crystal chemistry and phase transitions, the structure of the γ phase has been determined at 583 K using a single-crystal analysis. Both structural and nonlinear optical measurements indicate a β–γ first-order phase transition temperature that is close to 563 K. The structure of the γ phase is monoclinic (C2) and does not differ essentially from the α phase (C2). Comparison of the α and γ structures shows that the main atomic shifts and tiltings are connected with Te4, Te5 and Te6 pyramids.

Key indicators

• Single-crystal X-ray study
• T = 583 K
• Mean [sigma](e-O) = 0.027 Å
• R factor = 0.042
• wR factor = 0.103
• Data-to-parameter ratio = 12.5

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT432_ALERT_2_A Short Inter X...Y Contact  Te3    ..  O11     ..       2.92 Ang.

Author Response: see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O31     ..       2.87 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O33     ..       2.79 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.

PLAT432_ALERT_2_A Short Inter X...Y Contact  Te6    ..  O33     ..       2.79 Ang.

Author Response: see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O31     ..       2.87 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O33     ..       2.79 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.

PLAT432_ALERT_2_A Short Inter X...Y Contact  Te6    ..  O31     ..       2.87 Ang.

Author Response: see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O31     ..       2.87 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O33     ..       2.79 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.


Alert level B
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        Te1
PLAT430_ALERT_2_B Short Inter D...A Contact  O33    ..  O61     ..       2.82 Ang.
PLAT430_ALERT_2_B Short Inter D...A Contact  O51    ..  O61     ..       2.84 Ang.

Alert level C
CELLV02_ALERT_1_C  The supplied cell volume s.u. differs from that
            calculated from the cell parameter s.u.'s by > 2
            Calculated cell volume su =      10.27
            Cell volume su given      =       8.00
RADNW01_ALERT_1_C  The radiation wavelength lies outside the expected range
            for the supplied radiation type. Expected range 0.56080-0.56085
            Wavelength given =    0.56086
PLAT034_ALERT_1_C No Flack Parameter Given. Z .GT. Si, NonCentro .          ?
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT220_ALERT_2_C Large Non-Solvent    O     Ueq(max)/Ueq(min) ...       2.77 Ratio
PLAT220_ALERT_2_C Large Non-Solvent    O     Ueq(max)/Ueq(min) ...       2.69 Ratio
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Te2
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Te3
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Te4
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Te5
PLAT430_ALERT_2_C Short Inter D...A Contact  O23    ..  O42     ..       2.87 Ang.
PLAT432_ALERT_2_C Short Inter X...Y Contact  Te5    ..  O32     ..       3.28 Ang.

Author Response: see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O31     ..       2.87 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.

 PROBLEM: Short Inter X...Y Contact  Te6    ..  O33     ..       2.79 Ang.
 RESPONSE: see _publ_section_comment.
  see _publ_section_comment.


Alert level G
ABSTM02_ALERT_3_G  The ratio of expected to reported Tmax/Tmin(RR) is > 2.00
            Tmin and Tmax reported:      0.141     0.389
            Tmin and Tmax expected:      0.056     0.338
            RR =      2.203
            Please check that your absorption correction is appropriate.
REFLT03_ALERT_4_G  WARNING: Large fraction of Friedel related reflns may
                     be needed to determine absolute structure
           From the CIF: _diffrn_reflns_theta_max           19.97
           From the CIF: _reflns_number_total               2285
           Count of symmetry unique reflns         2293
           Completeness (_total/calc)             99.65%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present        yes
PLAT794_ALERT_5_G Check Predicted Bond Valency for Te1         (4)       4.69
PLAT794_ALERT_5_G Check Predicted Bond Valency for Te2         (4)       4.27
PLAT794_ALERT_5_G Check Predicted Bond Valency for Te3         (4)       4.10
PLAT794_ALERT_5_G Check Predicted Bond Valency for Te4         (4)       4.31
PLAT794_ALERT_5_G Check Predicted Bond Valency for Te5         (4)       4.02
PLAT794_ALERT_5_G Check Predicted Bond Valency for Te6         (4)       4.09
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   3 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
  12 ALERT level C = Check and explain
   9 ALERT level G = General alerts; check

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
  14 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   6 ALERT type 5 Informative message, check

---

S1. Comment

Although ferroelectric STO has been under intensive investigation for a long time (Yamada & Iwasaki,1972,1973; Simon et al.,1979; Libertz & Sadovskaya, 1980, Antonenko et al., 1982; Kudzin et al.,1988) there is still no a complete understanding of its rich polymorphism. Recently, in the two first papers of the present series the structures of α and β phases of STO were published (Zavodnik et al., 2007a, 2007b). The purpose of this communication is to report on the structure of γ-phase. There is a number of experimental studies of physical properties near the reversible first order β-γ phase transition (Libertz & Sadovskaya, 1980; Kudzin et al.,1982,1988, Sadovskaya, 1984). All the measured constants exhibit abrupt changes, a small thermal hysteresis and a remarkably discontinuous volume change were found (Ismailzade et al., 1979, Simon et al.,1979, Dityatiev et al., 2006). At 563 K the second harmonic generation (SHG) signal appeared, reflecting a transition to the noncentrosymmetric structure. The value of the spontaneous polarization along [010] polar axis was estimated as 0.037 c/m² at 585 K (Yamada & Iwasaki, 1972,1973). It was determined (Sadovskaya, 1984, Kudzin et al., 1988) that β-γ phase transition is connected with the formation and motion interfaces which are formed by crystallographic planes with indices (0 0 1) and (2 0 3). The peculiarities of the interface motion are the same as during the martensite transformation. No success was obtained in attempts to determine the γ-phase structure using X-ray and neutron powder diffraction (Simon et al.,1979; Ismailzade et al., 1979, Dityatiev et al., 2006). Last investigator (Dityatiev et al., 2006) believed that γ-STO at to be monoclinic C2/c. The polyhedral representation of γ-STO structure is presented on Figure 1. The current research indicates that γ-phase structure is supposed to be the same in many respects to α-phase structure. The Te—O bond lengths for Te3 and Te6 cations are located at distances greater than 2.7 Å and do not contribute to the first coordination sphere of Te⁴⁺. Figure 2 illustrates a comparison of α and γ-STO structures. The main atomic shifts and tiltings are connected with Te4, Te5 and Te6 pyramids while the maximum these values were observed for Te5 (O52α-O52γ 0.93 Å, O52α-Te5—O52γ 28.4°). It is not unreasonable to ask why the α and γ-phases separated by β-phase are structurally same. Full determination of the absolute configuration of γ-phase awaits the additional measurements and provides the means for tackling this important question. The relationship between the structures of the different phases will be describe later.

Related literature

Single crystals of SrTeO₃ (STO) were prepared by Sadovskaya (1984). Structural phase transitions of STO have been studied by X-ray powder diffraction by Ismailzade et al. (1979) and Simon et al. (1979), by neutron powder diffraction by Dityatiev et al. (2006), and by second harmonic generation by Libertz & Sadovskaya (1980). The temperature dependence of physical properties of STO was analysed by Yamada & Iwasaki (1972, 1973), Yamada (1975) and Kudzin et al. (1988). For related literature, see: Antonenko et al. (1982); Avramenko et al.(1984); Kudzin et al. (1982); Zavodnik et al. (2007a,b).

S2. Experimental

The single crystals of STO were grown by Czochralski technique as described earlier (Libertz & Sadovskaya, 1980; Avramenko et al., 1984). The products were characterized in a scanning electron microscope (Jeol 820) with an energy-dispersive spectrometer (LINK AN10000), confirming the presence and stoichiometry of Sr and Te. SHG measurements showed that there is no a symmetry centre in γ-phase which is stable between 563 K and 633 K with small thermal hysteresis (near 5 K). This conclusion is in a full agreement with the results of Libertz & Sadovskaya (1980). A special Enraf–Nonius mini-heater based on a goniometer head was used. The tested single-crystal was maintained by a special high-temperature silicate-based glue. The temperature interval of existence of the γ-phase was controlled by well calibrated thermocouple and with help of an appearance (or vanishing) of superstructural reflections (for example, (021) diffraction peak).

S3. Refinement

The structure of STO was solved by the direct method in space group C2 where the atomic coordinates of all Sr and Te cations were found. The O atoms were localized by difference Fourier maps. The selection of space group C2 for description of crystal structure of γ-phase STO was based on the experimental data of second harmonic generation (SHG) obtained on tested single crystals. The temperature dependence of SHG signal confirms that the structure of γ-phase STO is noncentrosymmetric with the polar axis along (010) direction. The choice of the portion of reciprocal space (k >0), used in our experiments results from the constructional features of high-temperature equipment. Secondly, the data collection of two equivalent sets of reflections was used for a performance evaluation of empirical absorption correction because the HABITUS of tested single-crystal was very far from a proper polyhedral shape. Absorption coefficient for used crystal is very high (µ=12.3 mm^-1 for Ag-radiation and µ=22.8 mm^-1 for Mo-radiation). We were unable to rely on the possibility to fix the effect of anomalous scattering using Ag-radiation because the maximum value Δf' for Te cations is equal to -1.212 (only 2.3%). Several additional experiments at 583 K on Mo-radiation were performed (as a supplementary to our experiment on Ag-radiation) using the identical single crystals with a significantly less size because of very strong absorbtion.In this case the maximum value of Δ f' for Sr cations is equal to -1.657 (4.5%). The absolute configuration of this phase was determined making use of anomalous scattering. For these additional data collections, the special modifications of Enraf–Nonius mini-heater were made in order to determine the intensities of Friedel pairs (hkl) and (-h-k-l). For the experiment with best accuracy the following results were obtained: 1857 non-zero reflections including the Friedel pairs, the agreement factors- 0.041 and 0.045, Flack parameters- 0.11 (3) and 0.72 (4) for absolute and inverted structures, correspondingly. Precise X-ray diffraction study of single crystals at high temperatures is a challenging task because there is usually only a small number of measured X-ray reflections in the data and they cover a rather limited range of sinθ/λ. The thermal vibration parameters for oxygen anions were very high and strongly anisotropic. It was difficult to use an anisotropic approximation in these high-temperature refinements because the ratio of statistically reliable reflections to a number of refined parameters was very far from an optimal value. A positive definite refinements with anisotropic atomic displacement parameters were impossible for O atoms at 583 K. It was a main reason why the oxygen atoms were refined isotropically. A special attention must be given to the accuracy of interatomic distances of Te—O which are not rather similar as in the case of room temperature experiment for α-phase (Zavodnik et al.,2007a). But all these Te—O bond lengths can be found acceptable if we take into account the standard deviation. For polar space group C2 the origin was fixed along the polar b axis in least square refinements. The highest residual electron density peak is located 0.92Å from atom Te6 and the deepest hole is located 0.74 Å from atom O22. Several atoms (Te4,Te5, Sr6, O12, O42 and O52) have increased isotropic atomic displacement parameters. These atoms are located inside significant voids which are larger than the voids for the rest of the atoms. The same peculiarity was also observed for the α- and β-STO structures. At the heating of γ-phase there is structural phase transition C2->C2/m and at 583 K some indicators on the mirror plane m are remarkable.

Computing details

Data collection: CAD-4-PC (Enraf–Nonius, 1993); cell refinement: CAD-4-PC; data reduction: CAD-4-PC; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The crystal structure of γ-SrTeO3 at 583 K. The sequence of Sr polyhedra are presented, Te cations occupy two different kinds of voids in a three-dimensional lattice.
	Fig. 2. A comapison of crystal structure of α and γ phases of STO. The TeO3 units are shown. The Sr positions have been omitted for clarity.

strontium tellurite

Crystal data

SrTeO3	F(000) = 2736
Mr = 263.22	Dx = 4.789 Mg m^−3
Monoclinic, C2	Ag Kα radiation, λ = 0.56086 Å
Hall symbol: C 2y	Cell parameters from 24 reflections
a = 28.262 (6) Å	θ = 12.3–14.5°
b = 5.935 (1) Å	µ = 12.04 mm^−1
c = 15.434 (3) Å	T = 583 K
β = 122.21 (3)°	Prism, colourless
V = 2190.4 (8) Å^3	0.24 × 0.22 × 0.09 mm
Z = 24

Data collection

Enraf–Nonius CAD-4 with high-temperature device diffractometer	1156 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.079
β-filter monochromator	θmax = 20.0°, θmin = 2.1°
ω/2θ scans	h = −30→34
Absorption correction: analytical (Alcock, 1970)	k = −7→0
Tmin = 0.141, Tmax = 0.389	l = −15→18
2335 measured reflections	3 standard reflections every 60 min
2285 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.042	w = 1/[σ^2(Fo^2) + (0.0585P)^2]
wR(F^2) = 0.103	(Δ/σ)max < 0.001
S = 0.94	Δρmax = 2.51 e Å^−3
2285 reflections	Δρmin = −2.18 e Å^−3
183 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.00036 (5)

Special details

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Te1	−0.01952 (6)	0.4326 (9)	0.14806 (10)	0.0371 (4)
Te2	0.49454 (5)	0.4367 (8)	0.65532 (10)	0.0286 (4)
Te3	0.11356 (5)	−0.0611 (7)	0.27897 (10)	0.0267 (4)
Te4	0.35558 (6)	−0.0645 (9)	0.22906 (13)	0.0434 (5)
Te5	0.14933 (6)	0.9420 (9)	−0.00044 (10)	0.0406 (4)
Te6	0.26226 (5)	0.4413 (7)	0.41764 (9)	0.0236 (3)
Sr1	0.12299 (7)	0.4497 (9)	0.42053 (14)	0.0296 (5)
Sr2	0.24724 (8)	0.4533 (9)	0.11004 (15)	0.0295 (5)
Sr3	0.24269 (9)	−0.0454 (11)	0.27598 (14)	0.0370 (6)
Sr4	0.37712 (8)	0.4159 (8)	0.39581 (16)	0.0282 (8)
Sr5	0.12480 (7)	0.4440 (12)	0.15394 (14)	0.0356 (6)
Sr6	0.0000	−0.079 (2)	0.0000	0.0601 (16)
Sr7	0.5000	0.9165 (19)	0.5000	0.0445 (15)
O11	0.0545 (8)	0.508 (4)	0.2171 (13)	0.048 (5)*
O12	−0.0152 (16)	0.145 (7)	0.108 (3)	0.133 (14)*
O13	−0.0485 (10)	0.573 (5)	0.0288 (17)	0.067 (7)*
O21	0.4447 (10)	0.656 (4)	0.5752 (18)	0.048 (7)*
O22	0.5460 (8)	0.527 (4)	0.6244 (14)	0.046 (5)*
O23	0.4556 (13)	0.202 (5)	0.564 (2)	0.065 (9)*
O31	0.1610 (9)	0.183 (4)	0.3309 (15)	0.037 (5)*
O32	0.0979 (7)	−0.011 (4)	0.1455 (11)	0.040 (5)*
O33	0.1708 (14)	−0.268 (6)	0.315 (2)	0.084 (10)*
O41	0.3210 (12)	−0.307 (5)	0.249 (2)	0.051 (8)*
O42	0.4061 (12)	0.010 (6)	0.363 (2)	0.103 (10)*
O43	0.3094 (11)	0.151 (5)	0.231 (2)	0.050 (8)*
O51	0.1802 (9)	0.719 (4)	0.1100 (16)	0.039 (5)*
O52	0.2047 (13)	1.015 (6)	−0.024 (2)	0.105 (11)*
O53	0.1681 (11)	1.195 (5)	0.0773 (19)	0.061 (8)*
O61	0.2331 (5)	0.418 (5)	0.2787 (9)	0.028 (3)*
O62	0.3166 (10)	0.657 (4)	0.4485 (18)	0.034 (6)*
O63	0.3064 (9)	0.190 (3)	0.4327 (16)	0.023 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Te1	0.0249 (6)	0.0491 (13)	0.0340 (7)	−0.001 (3)	0.0136 (6)	0.002 (3)
Te2	0.0245 (7)	0.0286 (10)	0.0334 (6)	−0.003 (2)	0.0160 (5)	0.001 (2)
Te3	0.0261 (7)	0.0251 (9)	0.0321 (6)	0.008 (2)	0.0176 (5)	0.012 (2)
Te4	0.0353 (8)	0.0342 (11)	0.0720 (11)	−0.003 (3)	0.0361 (8)	−0.002 (3)
Te5	0.0302 (7)	0.0469 (11)	0.0319 (7)	0.003 (3)	0.0079 (6)	0.005 (2)
Te6	0.0187 (5)	0.0240 (8)	0.0278 (6)	−0.004 (2)	0.0122 (5)	−0.004 (2)
Sr1	0.0267 (9)	0.0209 (13)	0.0326 (9)	−0.008 (2)	0.0099 (7)	−0.002 (2)
Sr2	0.0266 (9)	0.0217 (14)	0.0423 (10)	0.005 (2)	0.0197 (8)	0.002 (2)
Sr3	0.0384 (10)	0.0375 (17)	0.0323 (9)	0.001 (3)	0.0169 (8)	−0.002 (3)
Sr4	0.0218 (8)	0.024 (2)	0.0374 (9)	−0.0008 (14)	0.0151 (8)	0.0041 (15)
Sr5	0.0261 (9)	0.0453 (16)	0.0329 (9)	0.011 (3)	0.0141 (8)	0.010 (3)
Sr6	0.0311 (15)	0.077 (5)	0.0444 (17)	0.000	0.0016 (13)	0.000
Sr7	0.0217 (13)	0.062 (4)	0.0467 (16)	0.000	0.0161 (12)	0.000

Geometric parameters (Å, º)

Te1—O13	1.77 (2)	Sr4—O43	2.72 (3)
Te1—O11	1.827 (19)	Sr4—O21	2.78 (2)
Te1—O12	1.84 (4)	Sr5—O53^v	2.58 (3)
Te2—O21	1.83 (2)	Sr5—O51	2.59 (2)
Te2—O22	1.84 (2)	Sr5—O13^vii	2.59 (2)
Te2—O23	1.86 (3)	Sr5—O61	2.611 (12)
Te3—O31	1.84 (2)	Sr5—O11	2.66 (2)
Te3—O33	1.86 (4)	Sr5—O33^iii	2.71 (3)
Te3—O32	1.886 (16)	Sr5—O32	2.79 (2)
Te4—O42	1.84 (3)	Sr5—O31	2.82 (2)
Te4—O43	1.84 (3)	Sr5—O32^iii	3.31 (2)
Te4—O41	1.85 (3)	Sr6—O12	2.34 (4)
Te5—O53	1.81 (3)	Sr6—O12^vii	2.34 (4)
Te5—O52	1.84 (3)	Sr6—O32	2.496 (16)
Te5—O51	1.96 (2)	Sr6—O32^vii	2.496 (16)
Te6—O61	1.848 (12)	Sr6—O13^viii	2.65 (3)
Te6—O62	1.85 (2)	Sr6—O13^v	2.65 (3)
Te6—O63	1.88 (2)	Sr7—O42^ix	2.42 (3)
Sr1—O63^i	2.52 (2)	Sr7—O42^iii	2.42 (3)
Sr1—O62^ii	2.52 (2)	Sr7—O23^ix	2.60 (3)
Sr1—O21^ii	2.61 (3)	Sr7—O23^iii	2.60 (3)
Sr1—O31	2.68 (2)	Sr7—O22^vi	2.84 (2)
Sr1—O11	2.692 (18)	Sr7—O22	2.84 (2)
Sr1—O23^i	2.79 (3)	Sr7—O21	2.85 (3)
Sr1—O33^iii	3.10 (4)	Sr7—O21^vi	2.85 (3)
Sr2—O52^iv	2.37 (3)	O13—Sr5^vii	2.59 (2)
Sr2—O51	2.47 (2)	O13—Sr6^iii	2.65 (3)
Sr2—O41^iii	2.49 (3)	O21—Sr1^i	2.61 (3)
Sr2—O43	2.51 (3)	O22—Sr4^vi	2.44 (2)
Sr2—O53^v	2.53 (3)	O23—Sr7^v	2.60 (3)
Sr2—O61	2.844 (13)	O23—Sr1^ii	2.79 (3)
Sr2—O52^v	3.14 (3)	O32—Sr5^v	3.31 (2)
Sr3—O63	2.53 (2)	O33—Sr5^v	2.71 (3)
Sr3—O43	2.61 (3)	O33—Sr1^v	3.10 (4)
Sr3—O51^v	2.61 (2)	O41—Sr2^v	2.49 (3)
Sr3—O33	2.75 (4)	O41—Sr4^v	2.55 (3)
Sr3—O61	2.77 (3)	O42—Sr7^v	2.42 (3)
Sr3—O41	2.91 (3)	O51—Sr3^iii	2.61 (2)
Sr3—O62^v	2.94 (2)	O52—Sr2^x	2.37 (3)
Sr3—O53^v	3.00 (3)	O52—Sr2^iii	3.14 (3)
Sr3—O31	3.16 (2)	O53—Sr2^iii	2.53 (3)
Sr3—O61^v	3.20 (3)	O53—Sr5^iii	2.58 (3)
Sr4—O22^vi	2.44 (2)	O53—Sr3^iii	3.00 (3)
Sr4—O41^iii	2.55 (3)	O61—Sr3^iii	3.20 (3)
Sr4—O62	2.67 (3)	O62—Sr1^i	2.52 (2)
Sr4—O23	2.67 (3)	O62—Sr3^iii	2.94 (2)
Sr4—O42	2.68 (4)	O63—Sr1^ii	2.52 (2)
Sr4—O63	2.71 (2)
O13—Te1—O11	104.0 (10)	O22^vi—Sr4—O62	130.8 (7)
O13—Te1—O12	99.3 (15)	O41^iii—Sr4—O62	74.3 (9)
O11—Te1—O12	99.4 (14)	O22^vi—Sr4—O23	85.3 (8)
O21—Te2—O22	92.8 (11)	O41^iii—Sr4—O23	165.8 (9)
O21—Te2—O23	95.1 (9)	O62—Sr4—O23	107.0 (8)
O22—Te2—O23	104.6 (12)	O22^vi—Sr4—O42	80.6 (9)
O31—Te3—O33	94.2 (12)	O41^iii—Sr4—O42	121.4 (9)
O31—Te3—O32	92.5 (9)	O62—Sr4—O42	148.2 (9)
O33—Te3—O32	95.2 (12)	O23—Sr4—O42	65.0 (9)
O42—Te4—O43	86.8 (14)	O22^vi—Sr4—O63	165.1 (7)
O42—Te4—O41	99.3 (13)	O41^iii—Sr4—O63	109.1 (8)
O43—Te4—O41	95.5 (10)	O62—Sr4—O63	62.3 (5)
O53—Te5—O52	87.6 (14)	O23—Sr4—O63	83.3 (8)
O53—Te5—O51	98.4 (11)	O42—Sr4—O63	85.9 (8)
O52—Te5—O51	107.6 (12)	O22^vi—Sr4—O43	105.5 (8)
O61—Te6—O62	98.4 (10)	O41^iii—Sr4—O43	75.5 (6)
O61—Te6—O63	86.5 (10)	O62—Sr4—O43	110.3 (8)
O62—Te6—O63	96.4 (8)	O23—Sr4—O43	116.1 (9)
O63^i—Sr1—O62^ii	78.2 (6)	O42—Sr4—O43	55.8 (8)
O63^i—Sr1—O21^ii	126.5 (8)	O63—Sr4—O43	71.3 (8)
O62^ii—Sr1—O21^ii	73.2 (8)	O22^vi—Sr4—O21	78.7 (7)
O63^i—Sr1—O31	117.1 (7)	O41^iii—Sr4—O21	109.0 (8)
O62^ii—Sr1—O31	73.7 (7)	O62—Sr4—O21	68.4 (8)
O21^ii—Sr1—O31	96.9 (8)	O23—Sr4—O21	60.0 (6)
O63^i—Sr1—O11	135.2 (7)	O42—Sr4—O21	122.2 (8)
O62^ii—Sr1—O11	141.5 (8)	O63—Sr4—O21	103.7 (8)
O21^ii—Sr1—O11	92.0 (7)	O43—Sr4—O21	174.4 (8)
O31—Sr1—O11	73.2 (6)	O53^v—Sr5—O51	74.9 (7)
O63^i—Sr1—O23^i	84.5 (8)	O53^v—Sr5—O13^vii	89.6 (8)
O62^ii—Sr1—O23^i	122.2 (9)	O51—Sr5—O13^vii	78.3 (7)
O21^ii—Sr1—O23^i	74.4 (8)	O53^v—Sr5—O61	69.3 (7)
O31—Sr1—O23^i	156.7 (7)	O51—Sr5—O61	66.2 (7)
O11—Sr1—O23^i	85.4 (7)	O13^vii—Sr5—O61	142.1 (7)
O63^i—Sr1—O33^iii	78.9 (8)	O53^v—Sr5—O11	151.6 (8)
O62^ii—Sr1—O33^iii	119.7 (9)	O51—Sr5—O11	132.7 (7)
O21^ii—Sr1—O33^iii	154.4 (8)	O13^vii—Sr5—O11	90.3 (7)
O31—Sr1—O33^iii	68.9 (6)	O61—Sr5—O11	123.2 (5)
O11—Sr1—O33^iii	64.0 (7)	O53^v—Sr5—O33^iii	132.1 (10)
O23^i—Sr1—O33^iii	110.1 (10)	O51—Sr5—O33^iii	77.3 (9)
O52^iv—Sr2—O51	124.7 (10)	O13^vii—Sr5—O33^iii	121.8 (10)
O52^iv—Sr2—O41^iii	85.8 (11)	O61—Sr5—O33^iii	63.9 (9)
O51—Sr2—O41^iii	85.7 (9)	O11—Sr5—O33^iii	70.2 (9)
O52^iv—Sr2—O43	98.3 (11)	O53^v—Sr5—O32	66.9 (7)
O51—Sr2—O43	133.6 (9)	O51—Sr5—O32	141.8 (6)
O41^iii—Sr2—O43	80.4 (8)	O13^vii—Sr5—O32	100.7 (7)
O52^iv—Sr2—O53^v	133.5 (10)	O61—Sr5—O32	99.2 (7)
O51—Sr2—O53^v	77.9 (7)	O11—Sr5—O32	85.3 (6)
O41^iii—Sr2—O53^v	139.7 (9)	O33^iii—Sr5—O32	129.7 (8)
O43—Sr2—O53^v	84.8 (9)	O53^v—Sr5—O31	96.5 (8)
O52^iv—Sr2—O61	157.2 (8)	O51—Sr5—O31	130.0 (6)
O51—Sr2—O61	64.2 (7)	O13^vii—Sr5—O31	151.6 (7)
O41^iii—Sr2—O61	73.5 (8)	O61—Sr5—O31	64.8 (6)
O43—Sr2—O61	69.4 (8)	O11—Sr5—O31	71.4 (6)
O53^v—Sr2—O61	66.3 (7)	O33^iii—Sr5—O31	73.0 (8)
O52^iv—Sr2—O52^v	83.7 (8)	O32—Sr5—O31	57.5 (5)
O51—Sr2—O52^v	120.4 (8)	O53^v—Sr5—O32^iii	134.3 (7)
O41^iii—Sr2—O52^v	153.1 (9)	O51—Sr5—O32^iii	62.1 (6)
O43—Sr2—O52^v	76.7 (9)	O13^vii—Sr5—O32^iii	68.2 (7)
O53^v—Sr2—O52^v	51.7 (9)	O61—Sr5—O32^iii	104.0 (7)
O61—Sr2—O52^v	110.6 (8)	O11—Sr5—O32^iii	71.0 (6)
O63—Sr3—O43	76.0 (8)	O33^iii—Sr5—O32^iii	53.7 (8)
O63—Sr3—O51^v	176.9 (7)	O32—Sr5—O32^iii	153.2 (6)
O43—Sr3—O51^v	100.8 (8)	O31—Sr5—O32^iii	122.2 (6)
O63—Sr3—O33	106.8 (9)	O12—Sr6—O12^vii	111 (2)
O43—Sr3—O33	177.1 (10)	O12—Sr6—O32	78.8 (11)
O51^v—Sr3—O33	76.4 (8)	O12^vii—Sr6—O32	90.8 (11)
O63—Sr3—O61	57.4 (5)	O12—Sr6—O32^vii	90.8 (11)
O43—Sr3—O61	69.4 (7)	O12^vii—Sr6—O32^vii	78.8 (11)
O51^v—Sr3—O61	121.8 (6)	O32—Sr6—O32^vii	161.6 (12)
O33—Sr3—O61	112.7 (8)	O12—Sr6—O13^viii	150.5 (10)
O63—Sr3—O41	102.9 (7)	O12^vii—Sr6—O13^viii	90.9 (12)
O43—Sr3—O41	59.2 (6)	O32—Sr6—O13^viii	81.5 (7)
O51^v—Sr3—O41	75.1 (7)	O32^vii—Sr6—O13^viii	113.5 (7)
O33—Sr3—O41	118.9 (10)	O12—Sr6—O13^v	90.9 (12)
O61—Sr3—O41	128.3 (6)	O12^vii—Sr6—O13^v	150.5 (10)
O63—Sr3—O62^v	70.5 (4)	O32—Sr6—O13^v	113.5 (7)
O43—Sr3—O62^v	104.1 (8)	O32^vii—Sr6—O13^v	81.5 (7)
O51^v—Sr3—O62^v	110.4 (7)	O13^viii—Sr6—O13^v	77.1 (12)
O33—Sr3—O62^v	76.3 (9)	O42^ix—Sr7—O42^iii	153.4 (18)
O61—Sr3—O62^v	127.8 (5)	O42^ix—Sr7—O23^ix	69.8 (10)
O41—Sr3—O62^v	65.2 (7)	O42^iii—Sr7—O23^ix	92.6 (11)
O63—Sr3—O53^v	118.0 (7)	O42^ix—Sr7—O23^iii	92.6 (11)
O43—Sr3—O53^v	74.3 (8)	O42^iii—Sr7—O23^iii	69.8 (10)
O51^v—Sr3—O53^v	60.8 (6)	O23^ix—Sr7—O23^iii	98.5 (14)
O33—Sr3—O53^v	104.7 (9)	O42^ix—Sr7—O22^vi	132.3 (10)
O61—Sr3—O53^v	61.4 (6)	O42^iii—Sr7—O22^vi	72.7 (10)
O41—Sr3—O53^v	106.3 (8)	O23^ix—Sr7—O22^vi	114.5 (7)
O62^v—Sr3—O53^v	170.0 (7)	O23^iii—Sr7—O22^vi	130.4 (8)
O63—Sr3—O31	75.8 (6)	O42^ix—Sr7—O22	72.7 (10)
O43—Sr3—O31	127.9 (8)	O42^iii—Sr7—O22	132.3 (10)
O51^v—Sr3—O31	106.5 (6)	O23^ix—Sr7—O22	130.4 (8)
O33—Sr3—O31	54.2 (7)	O23^iii—Sr7—O22	114.5 (7)
O61—Sr3—O31	58.5 (5)	O22^vi—Sr7—O22	70.9 (8)
O41—Sr3—O31	171.2 (7)	O42^ix—Sr7—O21	110.7 (9)
O62^v—Sr3—O31	106.5 (6)	O42^iii—Sr7—O21	84.0 (9)
O53^v—Sr3—O31	81.6 (7)	O23^ix—Sr7—O21	172.1 (11)
O63—Sr3—O61^v	124.0 (5)	O23^iii—Sr7—O21	73.6 (7)
O43—Sr3—O61^v	121.9 (7)	O22^vi—Sr7—O21	71.4 (7)
O51^v—Sr3—O61^v	57.4 (6)	O22—Sr7—O21	55.7 (7)
O33—Sr3—O61^v	56.0 (8)	O42^ix—Sr7—O21^vi	84.0 (9)
O61—Sr3—O61^v	168.6 (5)	O42^iii—Sr7—O21^vi	110.7 (9)
O41—Sr3—O61^v	63.1 (6)	O23^ix—Sr7—O21^vi	73.6 (7)
O62^v—Sr3—O61^v	54.1 (5)	O23^iii—Sr7—O21^vi	172.1 (11)
O53^v—Sr3—O61^v	118.0 (6)	O22^vi—Sr7—O21^vi	55.7 (7)
O31—Sr3—O61^v	110.2 (5)	O22—Sr7—O21^vi	71.4 (7)
O22^vi—Sr4—O41^iii	83.5 (8)	O21—Sr7—O21^vi	114.3 (11)

Symmetry codes: (i) −x+1/2, y+1/2, −z+1; (ii) −x+1/2, y−1/2, −z+1; (iii) x, y+1, z; (iv) −x+1/2, y−1/2, −z; (v) x, y−1, z; (vi) −x+1, y, −z+1; (vii) −x, y, −z; (viii) −x, y−1, −z; (ix) −x+1, y+1, −z+1; (x) −x+1/2, y+1/2, −z.