Structure of strontium barium niobate Sr_xBa_1 − xNb₂O₆ (SBN) in the composition range 0.32 ≤ x ≤ 0.82

The structure of strontium barium niobate crystals Sr_xBa_1 − xNb₂O₆ is comprehensively studied in the whole range of the tetragonal tungsten bronze phase (x = 0.32–0.82) using both powder and single-crystal X-ray diffraction measurements. Unit-cell parameters, density, site-occupancy factors and interionic distances show an explicit composition dependence which can be consistently explained using simple model calculations. The temperature dependence of the unit-cell parameters exhibits a remarkable anisotropy in a broad temperature region below the phase transition temperature. This proves that the electrostrictive contribution to the thermal expansion plays an important role in strontium barium niobate.

1. Introduction

Strontium barium niobate, Sr_xBa_1-xNb₂O₆ (SBN), is an extensively studied ferroelectric material for electrooptic and photorefractive applications owing to its high electrooptic (r₃₃ = 420 pm V⁻¹ for x = 0.61) and piezoelectric coefficients (Neurgaonkar et al., 1984). Utilizing the high four-wave coupling coefficient in Ce-doped SBN, holographic applications of doped SBN (Volk et al., 1997) were also investigated. Most investigations were restricted to the congruently melting composition with x = 0.61, because for this composition crystals of high optical quality are available. The motivation to study SBN crystals with other strontium concentrations is the strong compositional dependence of the phase transition temperature. It changes from 503 K for x = 0.32 to ca 283 K for x = 0.82 (David et al., 2004). Taking advantage of this dependence, the electrooptic coefficients for room temperature can be optimized using appropriate Sr concentrations (r₃₃ = 1400 for x = 0.75; Neurgaonkar et al., 1984).

SBN belongs to the group of relaxor ferroelectrics. A typical phenomenon for this class is a broadened phase transition which is probably caused by the wide variation of the non-equivalent crystallographic positions in its structure. A first structural characterization was made in 1969 (Jamieson et al., 1968) for the composition x = 0.75. The ferroelectric relaxor SBN belongs to the structure type of tetragonal tungsten bronze (TTB) with the space group P4bm at room temperature (see Fig. 1). Sr and Ba occupy the A1 and A2 positions; while the smaller 12-fold coordinated A1 site is occupied only by Sr, both Sr and Ba are found in the larger 15-fold coordinated A2 site. This cation distribution was recently confirmed for SBN crystals with x = 0.61 (Chernaya et al., 1997) and 0.75 (Chernaya et al., 2000).

Figure 1 Crystal structure of the tetragonal tungsten bronze.

The compositional range of the ferroelectric TTB phase has usually been defined as x = 0.25–0.75. The existence range of tetragonal SBN was recently corrected to be x = 0.32–0.82 (Ulex et al., 2004). The aim of this work is a structure determination for the whole compositional range of SBN by means of X-ray diffraction measurements for both single-crystal and powder samples, with special attention on the cation distribution and the parameters of the Nb coordination polyhedron in the unit cell.

2. Experimental

2.1. Crystals

Single crystals of SBN (x = 0.32–0.82) were grown by the Czochralski technique using resistance heating. The detailed description of growth procedures can be found elsewhere (Ulex et al., 2004). The crystals were grown along the [001] direction; they exhibit a slight yellow colouration and show the form of prisms with 16 natural facets. The crystal diameter is between 5 and 7 mm. For the single-crystal X-ray measurements, as-grown (unpoled) single crystals were ground in an agate mortar followed by grinding in a ball mill. These operations produced single-crystalline spherical particles with diameters between 50 and 100m. The samples for the powder X-ray diffractometry were also produced by grinding grown crystals.

2.2. X-ray diffraction measurements

X-ray powder diffraction measurements were performed on crystal powder samples consisting of 40 mg SBN and 12 mg F-phlogopite as standard, using Cu K radiation. The single-crystal X-ray diffraction measurements were carried out on a four-circle kappa diffractometer (Xcalibur from Oxford Diffraction) equipped with a Sapphire2 CCD area detector. Graphite-monochromatized Mo K radiation was used. The sample-to-detector distance was 44.4 mm. With one and four scans, 93.2% of reciprocal space was covered which corresponds to 100% completeness under Laue group 4/m mm at a resolution of 0.8 Å. Data reduction and numerical absorption correction were carried out with the program CrysAlisRED (Oxford Diffraction, 2002). The crystal structure was refined with the program SHELXL97 (Sheldrick, 1997).

All measurements (except those for the temperature dependence of the unit-cell parameters) were carried out at room temperature.

3. Results and discussion

3.1. Unit-cell parameters

Powder X-ray measurements were performed throughout the compositional range x(Sr) from 0.32 to 0.82 with composition steps of ca 0.03. From these measurements, the unit-cell parameters a and c could be derived with an accuracy of approximately 3×10^-5.

The a parameter lies between 1248.5 and 1241.1 pm and the c parameter varies from 397.4 to 389.9 pm. Both a and c unit-cell parameters decrease with increasing Sr concentration. The dependence of the unit-cell parameters on the Sr concentration is shown in Fig. 2. The unit-cell parameters for the composition x = 0.61 are in good agreement with previously reported data (Chernaya et al., 1997). For comparison, the unit-cell parameters resulting from the single-crystal measurements (see below) are also plotted.

Figure 2 Unit-cell parameters of strontium barium niobate SrxBa1-xNb2O6 as a function of the strontium content x derived from powder (circles and squares) and single-crystal (filled triangles) X-ray measurements. Lines denote fits to the powder data.

The composition dependence of the unit-cell parameters can be described using second-order polynomial fits to the powder data

plotted as lines in Fig. 2. A quadratic term is included in both (1) and (2) to account for the slight deviations from Vegard's rule visible in the data. From Vegard's rule, a strictly linear dependence would be expected.

The overall variation of the unit-cell volume is approximately 3%. This can be fully ascribed to the variation of the effective average radii r_eff of the cations occupying the A1 and A2 sites (r_eff = 142–134 pm for r_Ba = 147 pm and r_Sr = 131 pm (Shannon & Prewitt, 1969, 1970), if one takes into account that approximately 15% of the unit-cell volume belongs to the A1 and A2 sites.

In Fig. 3 the measured unit-cell values are compared with the data for other ferroelectrics with the TTB structure. The Sr-rich compositions of SBN show rather small unit-cell parameters. This could be one of the reasons for the high values of the spontaneous polarization P_s and in turn the electrooptic coefficient r_ij in SBN.

Figure 3 SBN unit-cell parameters compared with other ferroelectrics from the TTB family (after Neurgaonkar & Cory, 1986).

3.2. Density

The density of the crystals was measured by hydrostatic technique on SBN samples with a typical volume of some cubic centimeters using distilled water as the immersion liquid. Thus, a good accuracy was achieved. The results are plotted in Fig. 4 together with the calculated X-ray density. For the calculation, the composition-dependent unit-cell parameters as given in (1) and (2) are used. A second-order polynomial fit to the X-ray density yields

Again the quadratic term is included to account for deviations from Vegard's rule.

Figure 4 Density of SBN as a function of the Sr content. Squares denote measured data (Archimedes principle); the line shows the X-ray density calculated using the unit-cell parameters.

3.3. Site-occupancy factors

Single-crystal X-ray diffraction measurements were performed on Sr_xBa_1-xNb₂O₆ crystals with x equal to 0.342, 0.477, 0.613 and 0.822. For all these compositions the structure refinement led to the tetragonal structure type with the space group P4bm.

The site-occupancy factors (s.o.f.) for the cation sites A1 and A2, derived from the measurement, are shown in Fig. 5. Site-occupancy factors are defined as

where M_i is the number of atoms per formula unit on site i, N the number of formula units per unit cell and Z the number of symmetry-equivalent sites in the unit cell. For SBN, N = 5, Z = 8, and the sum of the M_i for the A1 and A2 sites is 1. The 12-fold coordinated A1 sites are occupied by Sr cations only, the site-occupancy factor s.o.f.(Sr—A1) depends only slightly on the composition and varies between 0.16 and 0.18 corresponding to a relative occupancy between 66 and 72%. The 15-fold coordinated A2 sites are occupied by both Sr and Ba cations with an approximately linear composition dependence of the respective s.o.f. values. The total relative occupancy for the A2 sites is ca 90%.

Figure 5 Site-occupancy factors for A1 and A2 sites in SBN. Dots indicate measured data: – this work; ▵ – Jamieson et al. (1968); □ – Chernaya et al. (1997); ▿ – Woike et al. (2003). The lines represent the results of a model calculation (see text).

The site-occupancy factors and their compositional dependence can be described by a simple statistical model. Assuming that Ba occupies only A2 sites and Sr randomly occupies A1 and the remaining A2 sites with different preferences yields the respective s.o.f. values as a function of the strontium fraction x

K is a factor denoting the preference of Sr for the A2 site compared with A1, with K = 1 for equal preferences. The results of the model calculation for K = 1.1, i.e. a slight preference for A2, are sketched as gray lines in Fig. 5. A satisfactory agreement with the experimental data was found.

3.4. Nb—O bond lengths

The Nb—O bond lengths for all the compositions studied lie between 180 and 214 pm. The mean bond length which characterizes the NbO₆ octahedron size decreases monotonically with increasing Sr concentration and reaches 195.8 pm for the x(Sr) = 0.82, which is only slightly larger than the value of 195.2 pm calculated for the `ideal' oxygen (ion radius 138 pm) octahedron. The maximal difference between Nb—O bond lengths describes the asymmetry of the Nb position within the octahedron and also becomes smaller for the Sr-richer crystals. The measured unit-cell parameters, site-occupancy factors and Nb—O distances are shown in Table 1. All experimental data are given in Table 2.¹

Table 1
Results of the X-ray diffraction measurements on Sr_xBa_1 − xNb₂O₆ single crystals of different strontium fraction x

Crystal		SBN-34	SBN-48	SBN-61	SBN-82
Strontium fraction	x	0.342	0.477	0.613	0.822
Cell parameters	a (pm)	1248.40 (4)	1248.52 (6)	1245.9 (1)	1241.1 (5)
	c (pm)	397.42 (3)	395.66 (5)	393.6 (1)	389.9 (2)
Site occupancy	Sr—A1	0.1659 (3)	0.1777 (3)	0.1796 (3)	0.1758 (5)
	Ba—A2	0.4150 (4)	0.3300 (4)	0.2438 (4)	0.0942 (6)
	Sr—A2	0.0444 (4)	0.1170 (4)	0.2019 (4)	0.3550 (6)
Nb—O distance	Nb1 (pm)	197.10	197.01	196.66	195.78
Nb—O	Nb1 (pm)	30.1	28.3	33.4	16.1
Nb—O distance	Nb2 (pm)	198.16	197.83	197.19	196.57
Nb—O	Nb2 (pm)	30.2	28.2	23.9	7.7

Table 2
Experimental details

	k2shape	sr477	shape137	sbn159k3
Crystal data
Chemical formula	Ba0.67Nb2O6Sr0.33	Ba0.52Nb2O6Sr0.48	Ba0.39Nb2O6Sr0.61	Ba0.14Nb2O6Sr0.86
Mr	402.26	395.44	388.68	378.29
Cell setting, space group	Tetragonal, P4bm	Tetragonal, P4bm	Tetragonal, P4bm	Tetragonal, P4bm
Temperature (K)	298 (2)	298 (2)	298 (2)	298 (2)
a, c (Å)	12.4840 (4), 3.9742 (3)	12.4844 (5), 3.9572 (3)	12.4575 (7), 3.9382 (3)	12.4179 (9), 3.9074 (5)
V (Å^3)	619.38 (5)	616.77 (6)	611.17 (7)	602.54 (10)
Z	5	5	5	5
Dx (Mg m^−3)	5.392	5.323	5.282	5.216
Radiation type	Mo Kα	Mo Kα	Mo Kα	Mo Kα
μ (mm^−1)	13.33	13.78	14.31	15.13
Crystal form, colour	Sphere, colourless	Sphere, colourless	Sphere, colourless	Sphere, colourless
Crystal size (mm)	0.26 × 0.22 × 0.19	0.18 × 0.17 × 0.16	0.20 × 0.19 × 0.13	0.17 × 0.17 × 0.12
Data collection
Diffractometer	Xcalibur CCD	Xcalibur CCD	Xcalibur CCD	Xcalibur CCD
Data collection method	ω and φ	ω and φ	ω and φ	ω and φ
Absorption correction	Numerical	Numerical	Numerical	Numerical
Tmin	0.097	0.159	0.130	0.099
Tmax	0.177	0.221	0.267	0.169
No. of measured, independent and observed reflections	11 682, 2077, 1852	11 771, 2157, 1635	11 458, 2096, 1740	11 273, 2153, 1365
Criterion for observed reflections	I > 2σ(I)	I > 2σ(I)	I> 2σ(I)	I > 2σ(I)
Rint	0.034	0.038	0.039	0.060
θmax (°)	40.3	41.3	39.5	43.3
Refinement
Refinement on	F^2	F^2	F^2	F^2
R[F^2 > 2σ(F^2)], wR(F^2), S	0.027, 0.065, 1.12	0.030, 0.055, 1.00	0.033, 0.076, 1.14	0.045, 0.091, 0.96
No. of reflections	2077	2157	2096	2153
No. of parameters	65	65	65	65
Weighting scheme	w = 1/[σ^2(Fo^2) + (0.0303P)^2 + 1.1155P], where P = (Fo^2 + 2Fc^2)/3	w = 1/[σ^2(Fo^2) + (0.021P)^2], where P = (Fo^2 + 2Fc^2)/3	w = 1/[σ^2(Fo^2) + (0.0334P)^2 + 0.3182P], where P = (Fo^2 + 2Fc^2)/3	w = 1/[σ^2(Fo^2) + (0.0383P)^2], where P = (Fo^2 + 2Fc^2)/3
(Δ/σ)max	0.009	0.005	0.001	0.010
Δρmax, Δρmin (e Å^−3)	2.18, −2.79	2.12, −2.80	2.54, −3.17	3.63, −3.54
Extinction method	SHELXL	SHELXL	SHELXL	SHELXL
Extinction coefficient	0.0137 (3)	0.00421 (12)	0.0108 (3)	0.0118 (4)
Absolute structure	Flack (1983), 807 Friedel pairs	Flack (1983), 877 Friedel pairs	Flack (1983), 866 Friedel pairs	Flack (1983), 891 Friedel pairs
Computer programs used: CrysAlisCCD Oxford Diffraction, 2002), SHELXL97 (Sheldrick, 1997), WinGX (Farrugia, 1999).

3.5. Temperature dependence of the unit-cell parameters

Usually the unit-cell parameters of crystals increase monotonically with increasing temperature owing to the amplitudes of the ionic oscillations, increasing with increasing temperature. Thermal expansion measurements of SBN with x = 0.5 (Shorrocks et al., 1982) and x = 0.6 (Bhalla et al., 1987), however, show a negative temperature coefficient for the unit-cell parameter c at low temperatures and a positive one at higher temperatures with a minimum value of c near the phase-transition temperature. In contrast to this, the unit-cell parameter a always strictly increases with increasing temperature. Dilatometric measurements, however, are problematic in ferroelectric crystals owing to domain effects. Recent X-ray measurements (Qadri et al., 2005) for SBN with x = 0.75 confirm this anisotropic behavior – with a negative temperature coefficient for c, a positive one for a – throughout the temperature range investigated. To clarify the behavior, we extended the measurements of Quadri et al. (2005) up to higher temperatures on SBN with x = 0.822. The results are plotted in Fig. 6.

Figure 6 Temperature dependence of the unit-cell parameters a and c of SBN with an Sr content of 0.822 (black dots with error bars). For lower temperatures, the results taken from Quadri et al. (2005) were plotted (squares) and converted to different compositions (0.75 versus 0.822). The gray arrows denote the piezoelectric contributions to the thermal expansion (see text).

Our measurements show that X-ray measurements exhibit a similar behavior as found by thermal expansion measurements for other compositions: the a parameter strictly increases with temperature, whereas c decreases at low temperatures and increases at higher ones. An analog behavior has just been shown by neutron scattering measurements (Schefer et al., 2006).

The explanation for this behavior had already been given by Cross et al. (1980) and Shrout et al. (1981a,b), who derived an additional electrostrictive contribution to the thermal expansion of ferroelectrics from energetic considerations using the Landau–Ginsburg–Devonshire phenomenological theory. These contributions, Q₃₁P² for the unit-cell parameter a and Q₃₃P² for the unit-cell parameter c, are plotted as gray arrows in Fig. 6. For the calculation, the electrostriction constants Q_ik given by Cross et al. (1980) and a typical saturation polarization P = 0.3 C m^-2 were used.

4. Conclusion

Structural properties of strontium barium niobate crystals, Sr_xBa_1-xNb₂O₆, in the whole range of the tetragonal tungsten bronze phase (x = 0.32–0.82) have been comprehensively studied using powder and single-crystal X-ray diffraction. It has been shown that both unit-cell parameters a and c decrease with increasing x, i.e. with increasing strontium fraction. This effect can be fully attributed to the composition-dependent fraction of strontium and barium cations on the A1 and A2 sites, which results in a corresponding dependence of the average effective radii of the cations. Both unit-cell parameters are small compared with those of other TTB-type ferroelectrics. This may be one factor responsible for the high spontaneous polarization and the high electrooptic coefficients of the material.

Using the unit-cell parameters, the X-ray densities were calculated which were in excellent agreement with the macroscopic densities measured. Densities decrease with increasing strontium fraction.

From single-crystal X-ray measurements the site-occupancy factors for the A1 and A2 sites were derived; they showed a total occupancy of ca 70% for the A1 sites and ca 90% for the A2 sites. Absolute values and composition dependence can be consistently described by a simple statistical model.

The Nb—O distances varied only slightly with composition, whereas the off-center displacements of the Nb atoms showed a pronounced composition dependence owing to the fact that the phase-transition temperature was near room temperature at higher strontium fractions.

Temperature-dependent measurements of the unit-cell parameters for a composition of x = 0.822 confirmed earlier results found for SBN with other compositions. The a parameter strictly increases with increasing temperature, whereas the c parameter shows a more complicated behavior. At low temperatures c decreases, at high temperatures it increases with rising temperature, exhibiting a broad minimum in the region of the phase transition temperature. The effect can be well explained by an electrostrictive contribution to the thermal expansion.

Supporting information

Computing details

For all compounds, data collection: CrysAlis CCD Oxford Diffraction, 2002); cell refinement: CrysAlis CCD Oxford Diffraction, 2002). Data reduction: CrysAlis RED Oxford Diffraction, 2002) for k2shape, sr477, sbn159k3; CrysAlisREDOxford Diffraction, 2002) for shape137. For all compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

(k2shape)

Crystal data

Ba0.67Nb2O6Sr0.33	Dx = 5.392 Mg m^−3
Mr = 402.26	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4bm	Cell parameters from 8363 reflections
Hall symbol: P 4 -2ab	θ = 3–40°
a = 12.4840 (4) Å	µ = 13.33 mm^−1
c = 3.9742 (3) Å	T = 298 K
V = 619.38 (5) Å^3	Sphere, colourless
Z = 5	0.26 × 0.22 × 0.19 × 0.11 (radius) mm
F(000) = 900

Data collection

Xcalibur CCD diffractometer	2077 independent reflections
Radiation source: fine-focus sealed tube	1852 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ω and ϕ scans	θmax = 40.3°, θmin = 3.3°
Absorption correction: numerical after shape optimisation	h = −23→22
Tmin = 0.097, Tmax = 0.177	k = −22→21
11682 measured reflections	l = −7→6

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0303P)^2 + 1.1155P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.027	(Δ/σ)max = 0.009
wR(F^2) = 0.065	Δρmax = 2.18 e Å^−3
S = 1.12	Δρmin = −2.79 e Å^−3
2077 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
65 parameters	Extinction coefficient: 0.0137 (3)
2 restraints	Absolute structure: Flack H D (1983), 807 Friedel pairs
Primary atom site location: structure-invariant direct methods

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	Occ. (<1)
Ba2	0.17214 (2)	0.67214 (2)	0.49324 (10)	0.02297 (4)	0.8354 (8)
Sr2	0.17214 (2)	0.67214 (2)	0.49324 (10)	0.02297 (4)	0.0823 (8)
Sr1	0.0000	0.0000	0.4892 (2)	0.00861 (9)	0.6652 (11)
Nb1	0.5000	0.0000	0.01333 (14)	0.00785 (5)
Nb2	0.073922 (11)	0.211046 (11)	0.00295 (8)	0.00938 (3)
O1	0.28338 (12)	0.78338 (12)	0.9708 (9)	0.0137 (5)
O2	0.13965 (15)	0.07009 (12)	0.9572 (7)	0.0249 (6)
O3	0.99341 (13)	0.34380 (12)	0.9605 (7)	0.0216 (5)
O4	0.5000	0.0000	0.4752 (14)	0.0375 (11)
O5	0.0762 (2)	0.20507 (18)	0.4651 (6)	0.0374 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba2	0.02760 (6)	0.02760 (6)	0.01371 (8)	−0.01607 (7)	0.00026 (10)	0.00026 (10)
Sr2	0.02760 (6)	0.02760 (6)	0.01371 (8)	−0.01607 (7)	0.00026 (10)	0.00026 (10)
Sr1	0.00855 (10)	0.00855 (10)	0.0087 (2)	0.000	0.000	0.000
Nb1	0.00804 (6)	0.00804 (6)	0.00746 (11)	0.00052 (8)	0.000	0.000
Nb2	0.00941 (5)	0.00896 (5)	0.00978 (6)	0.00144 (4)	−0.00022 (11)	−0.00145 (12)
O1	0.0105 (4)	0.0105 (4)	0.0202 (12)	0.0038 (5)	0.0025 (7)	0.0025 (7)
O2	0.0188 (6)	0.0091 (5)	0.0469 (17)	0.0052 (5)	−0.0051 (10)	−0.0074 (9)
O3	0.0145 (6)	0.0067 (5)	0.0436 (14)	0.0035 (4)	−0.0027 (9)	−0.0006 (8)
O4	0.0472 (15)	0.0472 (15)	0.018 (2)	0.007 (2)	0.000	0.000
O5	0.0735 (16)	0.0319 (9)	0.0067 (12)	−0.0247 (9)	0.0003 (10)	−0.0030 (8)

Geometric parameters (Å, º)

Ba2—O1	2.731 (3)	Nb1—Sr2^xxi	3.6753 (4)
Ba2—O3^i	2.785 (2)	Nb2—O5	1.839 (2)
Ba2—O3^ii	2.785 (2)	Nb2—O3^xxii	1.9456 (15)
Ba2—O1^iii	2.858 (3)	Nb2—O2^iii	1.9501 (16)
Ba2—O3^iv	2.965 (2)	Nb2—O1^xx	2.0013 (15)
Ba2—O3^v	2.965 (2)	Nb2—O2^xiii	2.0149 (16)
Ba2—O4^vi	3.0399 (3)	Nb2—O5^iii	2.139 (2)
Ba2—O5^vi	3.170 (3)	Nb2—Sr1^iii	3.4587 (6)
Ba2—O5^vii	3.170 (3)	Nb2—Ba2^xix	3.7527 (3)
Ba2—O2^vi	3.247 (2)	Nb2—Sr2^xix	3.7527 (3)
Ba2—O2^vii	3.247 (2)	Nb2—Sr2^xx	3.7934 (3)
Ba2—Nb1^vi	3.5880 (4)	Nb2—Ba2^xx	3.7934 (3)
Sr1—O2	2.695 (2)	O1—Nb2^xxiii	2.0013 (15)
Sr1—O2^viii	2.695 (2)	O1—Nb2^xxiv	2.0013 (15)
Sr1—O2^ix	2.695 (2)	O1—Ba2^xxv	2.858 (3)
Sr1—O2^x	2.695 (2)	O1—Sr2^xxv	2.858 (3)
Sr1—O5	2.733 (2)	O2—Nb2^xxv	1.9501 (16)
Sr1—O5^ix	2.733 (2)	O2—Nb2^xxvi	2.0149 (16)
Sr1—O5^x	2.733 (2)	O2—Sr1^xxv	2.877 (3)
Sr1—O5^viii	2.733 (2)	O2—Ba2^xix	3.247 (2)
Sr1—O2^xi	2.877 (3)	O2—Sr2^xix	3.247 (2)
Sr1—O2^xii	2.877 (3)	O3—Nb2^xxvii	1.9456 (15)
Sr1—O2^xiii	2.877 (3)	O3—Nb1^xxviii	1.9630 (15)
Sr1—O2^iii	2.877 (3)	O3—Ba2^ii	2.785 (2)
Nb1—O4	1.835 (6)	O3—Sr2^ii	2.785 (2)
Nb1—O3^xiv	1.9630 (15)	O3—Sr2^xxix	2.965 (2)
Nb1—O3^xv	1.9630 (15)	O3—Ba2^xxix	2.965 (2)
Nb1—O3^xvi	1.9630 (15)	O4—Nb1^xxv	2.139 (6)
Nb1—O3^xvii	1.9630 (15)	O4—Ba2^xix	3.0399 (3)
Nb1—O4^iii	2.139 (6)	O4—Ba2^xviii	3.0399 (3)
Nb1—Ba2^xviii	3.5880 (4)	O4—Sr2^xix	3.0399 (3)
Nb1—Sr2^xix	3.5880 (4)	O4—Sr2^xviii	3.0399 (3)
Nb1—Ba2^xix	3.5880 (4)	O5—Nb2^xxv	2.139 (2)
Nb1—Sr2^xviii	3.5880 (4)	O5—Ba2^xix	3.170 (3)
Nb1—Sr2^xx	3.6753 (4)	O5—Sr2^xix	3.170 (3)
O1—Ba2—O3^i	87.15 (7)	Ba2^xviii—Nb1—Sr2^xix	115.776 (19)
O1—Ba2—O3^ii	87.15 (7)	O4—Nb1—Ba2^xix	57.888 (10)
O3^i—Ba2—O3^ii	56.61 (7)	O3^xiv—Nb1—Ba2^xix	55.72 (7)
O1—Ba2—O1^iii	90.61 (6)	O3^xv—Nb1—Ba2^xix	132.60 (6)
O3^i—Ba2—O1^iii	151.59 (3)	O3^xvi—Nb1—Ba2^xix	132.60 (6)
O3^ii—Ba2—O1^iii	151.59 (3)	O3^xvii—Nb1—Ba2^xix	55.72 (7)
O1—Ba2—O3^iv	152.21 (3)	O4^iii—Nb1—Ba2^xix	122.112 (10)
O3^i—Ba2—O3^iv	87.37 (4)	Ba2^xviii—Nb1—Ba2^xix	115.776 (19)
O3^ii—Ba2—O3^iv	112.11 (5)	O4—Nb1—Sr2^xviii	57.888 (10)
O1^iii—Ba2—O3^iv	81.52 (6)	O3^xiv—Nb1—Sr2^xviii	132.60 (6)
O1—Ba2—O3^v	152.21 (3)	O3^xv—Nb1—Sr2^xviii	55.72 (7)
O3^i—Ba2—O3^v	112.11 (5)	O3^xvi—Nb1—Sr2^xviii	55.72 (6)
O3^ii—Ba2—O3^v	87.37 (4)	O3^xvii—Nb1—Sr2^xviii	132.60 (6)
O1^iii—Ba2—O3^v	81.52 (6)	O4^iii—Nb1—Sr2^xviii	122.112 (10)
O3^iv—Ba2—O3^v	52.89 (6)	Sr2^xix—Nb1—Sr2^xviii	115.776 (19)
O1—Ba2—O4^vi	137.34 (12)	Ba2^xix—Nb1—Sr2^xviii	115.776 (19)
O3^i—Ba2—O4^vi	56.00 (10)	O4—Nb1—Sr2^xx	124.220 (9)
O3^ii—Ba2—O4^vi	56.00 (10)	O3^xiv—Nb1—Sr2^xx	48.28 (6)
O1^iii—Ba2—O4^vi	132.05 (12)	O3^xv—Nb1—Sr2^xx	123.03 (7)
O3^iv—Ba2—O4^vi	56.15 (10)	O3^xvi—Nb1—Sr2^xx	123.03 (7)
O3^v—Ba2—O4^vi	56.15 (10)	O3^xvii—Nb1—Sr2^xx	48.28 (6)
O1—Ba2—O5^vi	56.95 (6)	O4^iii—Nb1—Sr2^xx	55.780 (9)
O3^i—Ba2—O5^vi	100.98 (5)	Ba2^xviii—Nb1—Sr2^xx	177.892 (18)
O3^ii—Ba2—O5^vi	140.17 (6)	Sr2^xix—Nb1—Sr2^xx	66.332 (6)
O1^iii—Ba2—O5^vi	55.24 (6)	Ba2^xix—Nb1—Sr2^xx	66.332 (6)
O3^iv—Ba2—O5^vi	97.57 (5)	Sr2^xviii—Nb1—Sr2^xx	177.892 (18)
O3^v—Ba2—O5^vi	132.39 (6)	O4—Nb1—Sr2^xxi	124.220 (9)
O4^vi—Ba2—O5^vi	142.31 (4)	O3^xiv—Nb1—Sr2^xxi	123.03 (7)
O1—Ba2—O5^vii	56.95 (6)	O3^xv—Nb1—Sr2^xxi	48.28 (6)
O3^i—Ba2—O5^vii	140.17 (6)	O3^xvi—Nb1—Sr2^xxi	48.28 (6)
O3^ii—Ba2—O5^vii	100.98 (5)	O3^xvii—Nb1—Sr2^xxi	123.03 (7)
O1^iii—Ba2—O5^vii	55.24 (6)	O4^iii—Nb1—Sr2^xxi	55.780 (9)
O3^iv—Ba2—O5^vii	132.39 (6)	Ba2^xviii—Nb1—Sr2^xxi	66.332 (5)
O3^v—Ba2—O5^vii	97.57 (5)	Sr2^xix—Nb1—Sr2^xxi	177.892 (18)
O4^vi—Ba2—O5^vii	142.31 (4)	Ba2^xix—Nb1—Sr2^xxi	177.892 (18)
O5^vi—Ba2—O5^vii	75.03 (8)	Sr2^xviii—Nb1—Sr2^xxi	66.332 (5)
O1—Ba2—O2^vi	55.73 (4)	Sr2^xx—Nb1—Sr2^xxi	111.560 (18)
O3^i—Ba2—O2^vi	51.83 (5)	O5—Nb2—O3^xxii	97.43 (11)
O3^ii—Ba2—O2^vi	97.49 (6)	O5—Nb2—O2^iii	92.87 (11)
O1^iii—Ba2—O2^vi	104.57 (5)	O3^xxii—Nb2—O2^iii	167.94 (10)
O3^iv—Ba2—O2^vi	100.40 (5)	O5—Nb2—O1^xx	93.90 (13)
O3^v—Ba2—O2^vi	152.06 (4)	O3^xxii—Nb2—O1^xx	94.01 (7)
O4^vi—Ba2—O2^vi	104.34 (7)	O2^iii—Nb2—O1^xx	91.53 (8)
O5^vi—Ba2—O2^vi	49.75 (6)	O5—Nb2—O2^xiii	94.95 (11)
O5^vii—Ba2—O2^vi	108.36 (5)	O3^xxii—Nb2—O2^xiii	84.72 (7)
O1—Ba2—O2^vii	55.73 (4)	O2^iii—Nb2—O2^xiii	88.16 (10)
O3^i—Ba2—O2^vii	97.49 (6)	O1^xx—Nb2—O2^xiii	171.14 (12)
O3^ii—Ba2—O2^vii	51.83 (5)	O5—Nb2—O5^iii	175.36 (14)
O1^iii—Ba2—O2^vii	104.57 (5)	O3^xxii—Nb2—O5^iii	87.13 (10)
O3^iv—Ba2—O2^vii	152.06 (4)	O2^iii—Nb2—O5^iii	82.51 (11)
O3^v—Ba2—O2^vii	100.40 (5)	O1^xx—Nb2—O5^iii	86.55 (12)
O4^vi—Ba2—O2^vii	104.34 (7)	O2^xiii—Nb2—O5^iii	84.63 (10)
O5^vi—Ba2—O2^vii	108.36 (5)	O5—Nb2—Sr1	53.43 (7)
O5^vii—Ba2—O2^vii	49.75 (6)	O3^xxii—Nb2—Sr1	124.75 (6)
O2^vi—Ba2—O2^vii	104.21 (8)	O2^iii—Nb2—Sr1	57.81 (7)
O1—Ba2—Nb1^vi	168.09 (6)	O1^xx—Nb2—Sr1	128.93 (8)
O3^i—Ba2—Nb1^vi	82.37 (4)	O2^xiii—Nb2—Sr1	57.70 (7)
O3^ii—Ba2—Nb1^vi	82.37 (4)	O5^iii—Nb2—Sr1	123.05 (6)
O1^iii—Ba2—Nb1^vi	101.30 (6)	O5—Nb2—Sr1^iii	124.27 (7)
O3^iv—Ba2—Nb1^vi	33.16 (3)	O3^xxii—Nb2—Sr1^iii	117.38 (6)
O3^v—Ba2—Nb1^vi	33.16 (3)	O2^iii—Nb2—Sr1^iii	50.93 (7)
O4^vi—Ba2—Nb1^vi	30.76 (11)	O1^xx—Nb2—Sr1^iii	122.92 (8)
O5^vi—Ba2—Nb1^vi	130.73 (4)	O2^xiii—Nb2—Sr1^iii	51.07 (6)
O5^vii—Ba2—Nb1^vi	130.73 (4)	O5^iii—Nb2—Sr1^iii	52.20 (6)
O2^vi—Ba2—Nb1^vi	120.02 (3)	Sr1—Nb2—Sr1^iii	70.873 (5)
O2^vii—Ba2—Nb1^vi	120.02 (3)	O5—Nb2—Ba2^xix	57.50 (9)
O2—Sr1—O2^viii	61.56 (6)	O3^xxii—Nb2—Ba2^xix	126.28 (6)
O2—Sr1—O2^ix	61.56 (6)	O2^iii—Nb2—Ba2^xix	64.93 (6)
O2^viii—Sr1—O2^ix	92.73 (11)	O1^xx—Nb2—Ba2^xix	48.67 (8)
O2—Sr1—O2^x	92.73 (11)	O2^xiii—Nb2—Ba2^xix	138.02 (7)
O2^viii—Sr1—O2^x	61.56 (6)	O5^iii—Nb2—Ba2^xix	120.19 (8)
O2^ix—Sr1—O2^x	61.56 (6)	Sr1—Nb2—Ba2^xix	80.425 (9)
O2—Sr1—O5	59.65 (7)	Sr1^iii—Nb2—Ba2^xix	115.679 (7)
O2^viii—Sr1—O5	62.05 (7)	O5—Nb2—Sr2^xix	57.50 (9)
O2^ix—Sr1—O5	121.13 (7)	O3^xxii—Nb2—Sr2^xix	126.28 (6)
O2^x—Sr1—O5	123.61 (7)	O2^iii—Nb2—Sr2^xix	64.93 (6)
O2—Sr1—O5^ix	62.05 (7)	O1^xx—Nb2—Sr2^xix	48.67 (8)
O2^viii—Sr1—O5^ix	123.61 (7)	O2^xiii—Nb2—Sr2^xix	138.02 (7)
O2^ix—Sr1—O5^ix	59.65 (7)	O5^iii—Nb2—Sr2^xix	120.19 (8)
O2^x—Sr1—O5^ix	121.13 (7)	Sr1—Nb2—Sr2^xix	80.425 (9)
O5—Sr1—O5^ix	89.930 (4)	Sr1^iii—Nb2—Sr2^xix	115.679 (7)
O2—Sr1—O5^x	123.61 (7)	O5—Nb2—Sr2^xx	121.01 (9)
O2^viii—Sr1—O5^x	121.13 (7)	O3^xxii—Nb2—Sr2^xx	119.64 (6)
O2^ix—Sr1—O5^x	62.05 (7)	O2^iii—Nb2—Sr2^xx	58.87 (6)
O2^x—Sr1—O5^x	59.65 (7)	O1^xx—Nb2—Sr2^xx	43.93 (8)
O5—Sr1—O5^x	176.00 (10)	O2^xiii—Nb2—Sr2^xx	129.85 (7)
O5^ix—Sr1—O5^x	89.930 (4)	O5^iii—Nb2—Sr2^xx	56.67 (8)
O2—Sr1—O5^viii	121.13 (7)	Sr1—Nb2—Sr2^xx	115.576 (7)
O2^viii—Sr1—O5^viii	59.65 (7)	Sr1^iii—Nb2—Sr2^xx	79.058 (9)
O2^ix—Sr1—O5^viii	123.61 (7)	Ba2^xix—Nb2—Sr2^xx	63.557 (5)
O2^x—Sr1—O5^viii	62.05 (7)	Sr2^xix—Nb2—Sr2^xx	63.557 (5)
O5—Sr1—O5^viii	89.930 (4)	O5—Nb2—Ba2^xx	121.01 (9)
O5^ix—Sr1—O5^viii	176.00 (10)	O3^xxii—Nb2—Ba2^xx	119.64 (6)
O5^x—Sr1—O5^viii	89.930 (4)	O2^iii—Nb2—Ba2^xx	58.87 (6)
O2—Sr1—O2^xi	176.33 (8)	O1^xx—Nb2—Ba2^xx	43.93 (8)
O2^viii—Sr1—O2^xi	120.48 (3)	O2^xiii—Nb2—Ba2^xx	129.85 (7)
O2^ix—Sr1—O2^xi	120.48 (3)	O5^iii—Nb2—Ba2^xx	56.67 (8)
O2^x—Sr1—O2^xi	90.94 (5)	Sr1—Nb2—Ba2^xx	115.576 (7)
O5—Sr1—O2^xi	118.06 (7)	Sr1^iii—Nb2—Ba2^xx	79.058 (9)
O5^ix—Sr1—O2^xi	115.85 (7)	Ba2^xix—Nb2—Ba2^xx	63.557 (5)
O5^x—Sr1—O2^xi	58.56 (6)	Sr2^xix—Nb2—Ba2^xx	63.557 (5)
O5^viii—Sr1—O2^xi	60.83 (7)	Nb2^xxiii—O1—Nb2^xxiv	143.05 (12)
O2—Sr1—O2^xii	120.48 (3)	Nb2^xxiii—O1—Ba2	105.52 (9)
O2^viii—Sr1—O2^xii	176.33 (8)	Nb2^xxiv—O1—Ba2	105.52 (9)
O2^ix—Sr1—O2^xii	90.94 (5)	Nb2^xxiii—O1—Ba2^xxv	99.61 (9)
O2^x—Sr1—O2^xii	120.48 (3)	Nb2^xxiv—O1—Ba2^xxv	99.61 (9)
O5—Sr1—O2^xii	115.85 (7)	Ba2—O1—Ba2^xxv	90.61 (6)
O5^ix—Sr1—O2^xii	58.56 (6)	Nb2^xxiii—O1—Sr2^xxv	99.61 (9)
O5^x—Sr1—O2^xii	60.83 (7)	Nb2^xxiv—O1—Sr2^xxv	99.61 (9)
O5^viii—Sr1—O2^xii	118.06 (7)	Ba2—O1—Sr2^xxv	90.61 (6)
O2^xi—Sr1—O2^xii	57.30 (6)	Nb2^xxv—O2—Nb2^xxvi	169.37 (16)
O2—Sr1—O2^xiii	120.48 (3)	Nb2^xxv—O2—Sr1	94.89 (8)
O2^viii—Sr1—O2^xiii	90.94 (5)	Nb2^xxvi—O2—Sr1	93.37 (7)
O2^ix—Sr1—O2^xiii	176.33 (8)	Nb2^xxv—O2—Sr1^xxv	87.18 (8)
O2^x—Sr1—O2^xiii	120.48 (3)	Nb2^xxvi—O2—Sr1^xxv	86.00 (7)
O5—Sr1—O2^xiii	60.83 (7)	Sr1—O2—Sr1^xxv	90.94 (5)
O5^ix—Sr1—O2^xiii	118.06 (7)	Nb2^xxv—O2—Ba2^xix	90.20 (7)
O5^x—Sr1—O2^xiii	115.85 (7)	Nb2^xxvi—O2—Ba2^xix	94.66 (7)
O5^viii—Sr1—O2^xiii	58.56 (6)	Sr1—O2—Ba2^xix	101.75 (8)
O2^xi—Sr1—O2^xiii	57.30 (6)	Sr1^xxv—O2—Ba2^xix	167.22 (9)
O2^xii—Sr1—O2^xiii	85.39 (9)	Nb2^xxv—O2—Sr2^xix	90.20 (7)
O2—Sr1—O2^iii	90.94 (5)	Nb2^xxvi—O2—Sr2^xix	94.66 (7)
O2^viii—Sr1—O2^iii	120.48 (3)	Sr1—O2—Sr2^xix	101.75 (8)
O2^ix—Sr1—O2^iii	120.48 (3)	Sr1^xxv—O2—Sr2^xix	167.22 (9)
O2^x—Sr1—O2^iii	176.33 (8)	Nb2^xxvii—O3—Nb1^xxviii	144.61 (10)
O5—Sr1—O2^iii	58.56 (6)	Nb2^xxvii—O3—Ba2^ii	112.35 (8)
O5^ix—Sr1—O2^iii	60.83 (7)	Nb1^xxviii—O3—Ba2^ii	99.98 (7)
O5^x—Sr1—O2^iii	118.06 (7)	Nb2^xxvii—O3—Sr2^ii	112.35 (8)
O5^viii—Sr1—O2^iii	115.85 (7)	Nb1^xxviii—O3—Sr2^ii	99.98 (7)
O2^xi—Sr1—O2^iii	85.39 (9)	Nb2^xxvii—O3—Sr2^xxix	103.94 (8)
O2^xii—Sr1—O2^iii	57.30 (5)	Nb1^xxviii—O3—Sr2^xxix	91.11 (7)
O2^xiii—Sr1—O2^iii	57.30 (6)	Ba2^ii—O3—Sr2^xxix	87.37 (4)
O4—Nb1—O3^xiv	96.14 (8)	Sr2^ii—O3—Sr2^xxix	87.37 (4)
O4—Nb1—O3^xv	96.14 (8)	Nb2^xxvii—O3—Ba2^xxix	103.94 (8)
O3^xiv—Nb1—O3^xv	94.12 (9)	Nb1^xxviii—O3—Ba2^xxix	91.11 (7)
O4—Nb1—O3^xvi	96.14 (8)	Ba2^ii—O3—Ba2^xxix	87.37 (4)
O3^xiv—Nb1—O3^xvi	167.71 (16)	Sr2^ii—O3—Ba2^xxix	87.37 (4)
O3^xv—Nb1—O3^xvi	84.57 (9)	Nb1—O4—Nb1^xxv	180.0
O4—Nb1—O3^xvii	96.14 (8)	Nb1—O4—Ba2^xix	91.36 (11)
O3^xiv—Nb1—O3^xvii	84.57 (9)	Nb1^xxv—O4—Ba2^xix	88.64 (11)
O3^xv—Nb1—O3^xvii	167.71 (16)	Nb1—O4—Ba2^xviii	91.36 (11)
O3^xvi—Nb1—O3^xvii	94.12 (9)	Nb1^xxv—O4—Ba2^xviii	88.64 (11)
O4—Nb1—O4^iii	180.0	Ba2^xix—O4—Ba2^xviii	177.3 (2)
O3^xiv—Nb1—O4^iii	83.86 (8)	Nb1—O4—Sr2^xix	91.36 (11)
O3^xv—Nb1—O4^iii	83.86 (8)	Nb1^xxv—O4—Sr2^xix	88.64 (11)
O3^xvi—Nb1—O4^iii	83.86 (8)	Ba2^xviii—O4—Sr2^xix	177.3 (2)
O3^xvii—Nb1—O4^iii	83.86 (8)	Nb1—O4—Sr2^xviii	91.36 (11)
O4—Nb1—Ba2^xviii	57.888 (10)	Nb1^xxv—O4—Sr2^xviii	88.64 (11)
O3^xiv—Nb1—Ba2^xviii	132.60 (6)	Ba2^xix—O4—Sr2^xviii	177.3 (2)
O3^xv—Nb1—Ba2^xviii	55.72 (7)	Sr2^xix—O4—Sr2^xviii	177.3 (2)
O3^xvi—Nb1—Ba2^xviii	55.72 (6)	Nb2—O5—Nb2^xxv	175.36 (15)
O3^xvii—Nb1—Ba2^xviii	132.60 (6)	Nb2—O5—Sr1	93.86 (9)
O4^iii—Nb1—Ba2^xviii	122.112 (10)	Nb2^xxv—O5—Sr1	89.60 (8)
O4—Nb1—Sr2^xix	57.888 (10)	Nb2—O5—Ba2^xix	93.21 (10)
O3^xiv—Nb1—Sr2^xix	55.72 (7)	Nb2^xxv—O5—Ba2^xix	89.01 (9)
O3^xv—Nb1—Sr2^xix	132.60 (6)	Sr1—O5—Ba2^xix	102.85 (8)
O3^xvi—Nb1—Sr2^xix	132.60 (6)	Nb2—O5—Sr2^xix	93.21 (10)
O3^xvii—Nb1—Sr2^xix	55.72 (7)	Nb2^xxv—O5—Sr2^xix	89.01 (9)
O4^iii—Nb1—Sr2^xix	122.112 (10)	Sr1—O5—Sr2^xix	102.85 (8)

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

(sr477)

Crystal data

Ba0.52Nb2O6Sr0.48	Dx = 5.323 Mg m^−3
Mr = 395.44	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4bm	Cell parameters from 5168 reflections
Hall symbol: P 4 -2ab	θ = 3–40°
a = 12.4844 (5) Å	µ = 13.78 mm^−1
c = 3.9572 (3) Å	T = 298 K
V = 616.77 (6) Å^3	Sphere, colourless
Z = 5	0.18 × 0.17 × 0.16 × 0.08 (radius) mm
F(000) = 886.8

Data collection

Xcalibur CCD diffractometer	2157 independent reflections
Radiation source: fine-focus sealed tube	1635 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ω and ϕ scans	θmax = 41.3°, θmin = 3.3°
Absorption correction: numerical after shape optimisation	h = −23→21
Tmin = 0.159, Tmax = 0.221	k = −21→22
11771 measured reflections	l = −7→7

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.021P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.030	(Δ/σ)max = 0.005
wR(F^2) = 0.055	Δρmax = 2.12 e Å^−3
S = 1.00	Δρmin = −2.81 e Å^−3
2157 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
65 parameters	Extinction coefficient: 0.00421 (12)
2 restraints	Absolute structure: Flack H D (1983), 877 Friedel pairs
Primary atom site location: structure-invariant direct methods

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	Occ. (<1)
Ba2	0.17211 (2)	0.67211 (2)	0.49383 (13)	0.02465 (6)	0.6500 (7)
Sr2	0.17211 (2)	0.67211 (2)	0.49383 (13)	0.02465 (6)	0.2462 (8)
Sr1	0.0000	0.0000	0.4892 (2)	0.00814 (10)	0.7080 (10)
Nb1	0.5000	0.0000	0.01582 (16)	0.00804 (6)
Nb2	0.074263 (12)	0.211348 (12)	0.00129 (9)	0.00970 (3)
O1	0.28318 (12)	0.78318 (12)	0.9686 (9)	0.0159 (5)
O2	0.13908 (13)	0.06924 (12)	0.9585 (8)	0.0256 (6)
O3	0.99357 (12)	0.34369 (12)	0.9588 (8)	0.0245 (5)
O4	0.5000	0.0000	0.4788 (16)	0.0421 (11)
O5	0.07542 (19)	0.20469 (16)	0.4660 (6)	0.0427 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba2	0.02944 (7)	0.02944 (7)	0.01507 (10)	−0.01766 (9)	0.00011 (17)	0.00011 (17)
Sr2	0.02944 (7)	0.02944 (7)	0.01507 (10)	−0.01766 (9)	0.00011 (17)	0.00011 (17)
Sr1	0.00784 (11)	0.00784 (11)	0.0087 (2)	0.000	0.000	0.000
Nb1	0.00854 (7)	0.00854 (7)	0.00705 (13)	0.00056 (10)	0.000	0.000
Nb2	0.00949 (6)	0.00887 (6)	0.01073 (6)	0.00134 (5)	−0.00037 (17)	−0.00107 (19)
O1	0.0119 (5)	0.0119 (5)	0.0238 (15)	0.0038 (7)	0.0018 (10)	0.0018 (10)
O2	0.0184 (7)	0.0099 (6)	0.0486 (16)	0.0047 (6)	−0.0078 (12)	−0.0100 (11)
O3	0.0152 (7)	0.0092 (6)	0.0492 (15)	0.0056 (6)	−0.0024 (12)	−0.0038 (10)
O4	0.0563 (15)	0.0563 (15)	0.014 (2)	−0.008 (2)	0.000	0.000
O5	0.0907 (16)	0.0333 (9)	0.0041 (11)	−0.0306 (10)	0.0028 (12)	−0.0011 (10)

Geometric parameters (Å, º)

Ba2—O1	2.716 (3)	Nb1—Ba2^xx	3.6743 (5)
Ba2—O3^i	2.775 (2)	Nb2—O5	1.840 (2)
Ba2—O3^ii	2.775 (2)	Nb2—O3^xxi	1.9425 (15)
Ba2—O1^iii	2.857 (3)	Nb2—O2^iii	1.9574 (15)
Ba2—O3^iv	2.966 (2)	Nb2—O1^xxii	1.9972 (15)
Ba2—O3^v	2.966 (2)	Nb2—O2^xiii	2.0132 (15)
Ba2—O4^vi	3.0395 (3)	Nb2—O5^iii	2.120 (2)
Ba2—O5^vi	3.180 (2)	Nb2—Sr1^iii	3.4536 (6)
Ba2—O5^vii	3.180 (2)	Nb2—Ba2^xix	3.7503 (4)
Ba2—O2^vi	3.254 (2)	Nb2—Sr2^xix	3.7503 (4)
Ba2—O2^vii	3.254 (2)	Nb2—Sr2^xxii	3.7813 (4)
Ba2—Nb1^vi	3.5794 (5)	Nb2—Ba2^xxii	3.7813 (4)
Sr1—O2	2.685 (2)	O1—Nb2^xxiii	1.9972 (15)
Sr1—O2^viii	2.685 (2)	O1—Nb2^xxiv	1.9972 (15)
Sr1—O2^ix	2.685 (2)	O1—Ba2^xxv	2.857 (3)
Sr1—O2^x	2.685 (2)	O1—Sr2^xxv	2.857 (3)
Sr1—O5^ix	2.7252 (19)	O2—Nb2^xxv	1.9574 (15)
Sr1—O5^viii	2.7252 (19)	O2—Nb2^xxvi	2.0132 (15)
Sr1—O5	2.7252 (19)	O2—Sr1^xxv	2.859 (3)
Sr1—O5^x	2.7252 (19)	O2—Ba2^xix	3.254 (2)
Sr1—O2^xi	2.859 (3)	O2—Sr2^xix	3.254 (2)
Sr1—O2^xii	2.859 (3)	O3—Nb2^xxvii	1.9425 (15)
Sr1—O2^xiii	2.859 (3)	O3—Nb1^xxviii	1.9662 (15)
Sr1—O2^iii	2.859 (3)	O3—Ba2^ii	2.775 (2)
Nb1—O4	1.832 (6)	O3—Sr2^ii	2.775 (2)
Nb1—O3^xiv	1.9662 (15)	O3—Sr2^xxix	2.966 (2)
Nb1—O3^xv	1.9662 (15)	O3—Ba2^xxix	2.966 (2)
Nb1—O3^xvi	1.9662 (15)	O4—Nb1^xxv	2.125 (6)
Nb1—O3^xvii	1.9662 (15)	O4—Sr2^xviii	3.0395 (3)
Nb1—O4^iii	2.125 (6)	O4—Ba2^xviii	3.0395 (3)
Nb1—Ba2^xviii	3.5794 (5)	O4—Ba2^xix	3.0395 (3)
Nb1—Sr2^xviii	3.5794 (5)	O4—Sr2^xix	3.0395 (3)
Nb1—Ba2^xix	3.5794 (5)	O5—Nb2^xxv	2.120 (2)
Nb1—Sr2^xix	3.5794 (5)	O5—Ba2^xix	3.180 (2)
Nb1—Sr2^xx	3.6743 (5)	O5—Sr2^xix	3.180 (2)
O1—Ba2—O3^i	87.61 (8)	O4—Nb1—Ba2^xix	58.104 (12)
O1—Ba2—O3^ii	87.61 (8)	O3^xiv—Nb1—Ba2^xix	132.92 (7)
O3^i—Ba2—O3^ii	56.95 (7)	O3^xv—Nb1—Ba2^xix	55.96 (7)
O1—Ba2—O1^iii	90.43 (6)	O3^xvi—Nb1—Ba2^xix	55.96 (7)
O3^i—Ba2—O1^iii	151.44 (4)	O3^xvii—Nb1—Ba2^xix	132.92 (7)
O3^ii—Ba2—O1^iii	151.44 (3)	O4^iii—Nb1—Ba2^xix	121.896 (12)
O1—Ba2—O3^iv	152.09 (4)	Ba2^xviii—Nb1—Ba2^xix	116.21 (2)
O3^i—Ba2—O3^iv	87.05 (4)	Sr2^xviii—Nb1—Ba2^xix	116.21 (2)
O3^ii—Ba2—O3^iv	111.96 (6)	O4—Nb1—Sr2^xix	58.104 (12)
O1^iii—Ba2—O3^iv	81.47 (7)	O3^xiv—Nb1—Sr2^xix	132.92 (7)
O1—Ba2—O3^v	152.09 (4)	O3^xv—Nb1—Sr2^xix	55.96 (7)
O3^i—Ba2—O3^v	111.96 (6)	O3^xvi—Nb1—Sr2^xix	55.96 (7)
O3^ii—Ba2—O3^v	87.05 (4)	O3^xvii—Nb1—Sr2^xix	132.92 (7)
O1^iii—Ba2—O3^v	81.47 (7)	O4^iii—Nb1—Sr2^xix	121.896 (12)
O3^iv—Ba2—O3^v	52.98 (7)	Ba2^xviii—Nb1—Sr2^xix	116.21 (2)
O1—Ba2—O4^vi	137.35 (14)	Sr2^xviii—Nb1—Sr2^xix	116.21 (2)
O3^i—Ba2—O4^vi	55.65 (11)	O4—Nb1—Sr2^xx	124.201 (11)
O3^ii—Ba2—O4^vi	55.65 (11)	O3^xiv—Nb1—Sr2^xx	48.02 (7)
O1^iii—Ba2—O4^vi	132.22 (13)	O3^xv—Nb1—Sr2^xx	122.68 (7)
O3^iv—Ba2—O4^vi	56.36 (11)	O3^xvi—Nb1—Sr2^xx	122.68 (7)
O3^v—Ba2—O4^vi	56.36 (11)	O3^xvii—Nb1—Sr2^xx	48.02 (7)
O1—Ba2—O5^vi	56.81 (6)	O4^iii—Nb1—Sr2^xx	55.799 (11)
O3^i—Ba2—O5^vi	100.88 (5)	Ba2^xviii—Nb1—Sr2^xx	66.10 (1)
O3^ii—Ba2—O5^vi	140.43 (7)	Sr2^xviii—Nb1—Sr2^xx	66.10 (1)
O1^iii—Ba2—O5^vi	55.37 (6)	Ba2^xix—Nb1—Sr2^xx	177.70 (2)
O3^iv—Ba2—O5^vi	97.49 (5)	Sr2^xix—Nb1—Sr2^xx	177.70 (2)
O3^v—Ba2—O5^vi	132.45 (7)	O4—Nb1—Ba2^xx	124.201 (11)
O4^vi—Ba2—O5^vi	142.23 (4)	O3^xiv—Nb1—Ba2^xx	48.02 (7)
O1—Ba2—O5^vii	56.81 (6)	O3^xv—Nb1—Ba2^xx	122.68 (7)
O3^i—Ba2—O5^vii	140.43 (7)	O3^xvi—Nb1—Ba2^xx	122.68 (7)
O3^ii—Ba2—O5^vii	100.88 (5)	O3^xvii—Nb1—Ba2^xx	48.02 (7)
O1^iii—Ba2—O5^vii	55.37 (6)	O4^iii—Nb1—Ba2^xx	55.799 (11)
O3^iv—Ba2—O5^vii	132.45 (7)	Ba2^xviii—Nb1—Ba2^xx	66.10 (1)
O3^v—Ba2—O5^vii	97.49 (5)	Sr2^xviii—Nb1—Ba2^xx	66.10 (1)
O4^vi—Ba2—O5^vii	142.23 (4)	Ba2^xix—Nb1—Ba2^xx	177.70 (2)
O5^vi—Ba2—O5^vii	75.24 (7)	Sr2^xix—Nb1—Ba2^xx	177.70 (2)
O1—Ba2—O2^vi	56.00 (4)	O5—Nb2—O3^xxi	97.40 (11)
O3^i—Ba2—O2^vi	51.88 (5)	O5—Nb2—O2^iii	92.42 (11)
O3^ii—Ba2—O2^vi	97.89 (7)	O3^xxi—Nb2—O2^iii	167.95 (11)
O1^iii—Ba2—O2^vi	104.53 (5)	O5—Nb2—O1^xxii	94.47 (13)
O3^iv—Ba2—O2^vi	100.15 (5)	O3^xxi—Nb2—O1^xxii	94.28 (7)
O3^v—Ba2—O2^vi	151.91 (4)	O2^iii—Nb2—O1^xxii	91.89 (8)
O4^vi—Ba2—O2^vi	104.13 (7)	O5—Nb2—O2^xiii	94.05 (11)
O5^vi—Ba2—O2^vi	49.61 (6)	O3^xxi—Nb2—O2^xiii	84.97 (7)
O5^vii—Ba2—O2^vi	108.55 (5)	O2^iii—Nb2—O2^xiii	87.39 (10)
O1—Ba2—O2^vii	56.00 (4)	O1^xxii—Nb2—O2^xiii	171.47 (13)
O3^i—Ba2—O2^vii	97.89 (7)	O5—Nb2—O5^iii	175.09 (12)
O3^ii—Ba2—O2^vii	51.88 (5)	O3^xxi—Nb2—O5^iii	87.16 (11)
O1^iii—Ba2—O2^vii	104.53 (5)	O2^iii—Nb2—O5^iii	82.84 (11)
O3^iv—Ba2—O2^vii	151.91 (4)	O1^xxii—Nb2—O5^iii	86.95 (12)
O3^v—Ba2—O2^vii	100.15 (5)	O2^xiii—Nb2—O5^iii	84.52 (11)
O4^vi—Ba2—O2^vii	104.13 (7)	O5—Nb2—Sr1	53.10 (6)
O5^vi—Ba2—O2^vii	108.55 (5)	O3^xxi—Nb2—Sr1	124.61 (7)
O5^vii—Ba2—O2^vii	49.61 (6)	O2^iii—Nb2—Sr1	57.19 (7)
O2^vi—Ba2—O2^vii	104.63 (9)	O1^xxii—Nb2—Sr1	128.95 (8)
O1—Ba2—Nb1^vi	168.13 (7)	O2^xiii—Nb2—Sr1	57.11 (7)
O3^i—Ba2—Nb1^vi	81.96 (5)	O5^iii—Nb2—Sr1	122.62 (5)
O3^ii—Ba2—Nb1^vi	81.96 (5)	O5—Nb2—Sr1^iii	123.62 (6)
O1^iii—Ba2—Nb1^vi	101.44 (6)	O3^xxi—Nb2—Sr1^iii	117.38 (7)
O3^iv—Ba2—Nb1^vi	33.32 (3)	O2^iii—Nb2—Sr1^iii	50.78 (7)
O3^v—Ba2—Nb1^vi	33.32 (3)	O1^xxii—Nb2—Sr1^iii	122.98 (9)
O4^vi—Ba2—Nb1^vi	30.78 (12)	O2^xiii—Nb2—Sr1^iii	50.90 (7)
O5^vi—Ba2—Nb1^vi	130.81 (4)	O5^iii—Nb2—Sr1^iii	52.10 (5)
O5^vii—Ba2—Nb1^vi	130.81 (4)	Sr1—Nb2—Sr1^iii	70.535 (8)
O2^vi—Ba2—Nb1^vi	119.77 (3)	O5—Nb2—Ba2^xix	57.88 (7)
O2^vii—Ba2—Nb1^vi	119.77 (3)	O3^xxi—Nb2—Ba2^xix	126.44 (6)
O2—Sr1—O2^viii	61.43 (6)	O2^iii—Nb2—Ba2^xix	65.00 (7)
O2—Sr1—O2^ix	92.50 (11)	O1^xxii—Nb2—Ba2^xix	48.69 (9)
O2^viii—Sr1—O2^ix	61.43 (6)	O2^xiii—Nb2—Ba2^xix	137.44 (7)
O2—Sr1—O2^x	61.43 (6)	O5^iii—Nb2—Ba2^xix	120.55 (7)
O2^viii—Sr1—O2^x	92.50 (11)	Sr1—Nb2—Ba2^xix	80.430 (11)
O2^ix—Sr1—O2^x	61.43 (6)	Sr1^iii—Nb2—Ba2^xix	115.577 (8)
O2—Sr1—O5^ix	123.28 (7)	O5—Nb2—Sr2^xix	57.88 (7)
O2^viii—Sr1—O5^ix	121.23 (7)	O3^xxi—Nb2—Sr2^xix	126.44 (6)
O2^ix—Sr1—O5^ix	59.87 (7)	O2^iii—Nb2—Sr2^xix	65.00 (7)
O2^x—Sr1—O5^ix	61.85 (7)	O1^xxii—Nb2—Sr2^xix	48.69 (9)
O2—Sr1—O5^viii	121.23 (7)	O2^xiii—Nb2—Sr2^xix	137.44 (7)
O2^viii—Sr1—O5^viii	59.87 (7)	O5^iii—Nb2—Sr2^xix	120.55 (7)
O2^ix—Sr1—O5^viii	61.85 (7)	Sr1—Nb2—Sr2^xix	80.430 (11)
O2^x—Sr1—O5^viii	123.28 (7)	Sr1^iii—Nb2—Sr2^xix	115.577 (8)
O5^ix—Sr1—O5^viii	89.935 (4)	O5—Nb2—Sr2^xxii	121.20 (7)
O2—Sr1—O5	59.87 (7)	O3^xxi—Nb2—Sr2^xxii	119.91 (7)
O2^viii—Sr1—O5	61.85 (7)	O2^iii—Nb2—Sr2^xxii	59.37 (7)
O2^ix—Sr1—O5	123.28 (7)	O1^xxii—Nb2—Sr2^xxii	43.74 (9)
O2^x—Sr1—O5	121.23 (7)	O2^xiii—Nb2—Sr2^xxii	129.99 (7)
O5^ix—Sr1—O5	176.13 (11)	O5^iii—Nb2—Sr2^xxii	57.22 (6)
O5^viii—Sr1—O5	89.935 (4)	Sr1—Nb2—Sr2^xxii	115.437 (8)
O2—Sr1—O5^x	61.85 (7)	Sr1^iii—Nb2—Sr2^xxii	79.30 (1)
O2^viii—Sr1—O5^x	123.28 (7)	Ba2^xix—Nb2—Sr2^xxii	63.380 (8)
O2^ix—Sr1—O5^x	121.23 (7)	Sr2^xix—Nb2—Sr2^xxii	63.380 (8)
O2^x—Sr1—O5^x	59.87 (7)	O5—Nb2—Ba2^xxii	121.20 (7)
O5^ix—Sr1—O5^x	89.935 (4)	O3^xxi—Nb2—Ba2^xxii	119.91 (7)
O5^viii—Sr1—O5^x	176.13 (11)	O2^iii—Nb2—Ba2^xxii	59.37 (7)
O5—Sr1—O5^x	89.935 (4)	O1^xxii—Nb2—Ba2^xxii	43.74 (9)
O2—Sr1—O2^xi	176.48 (9)	O2^xiii—Nb2—Ba2^xxii	129.99 (7)
O2^viii—Sr1—O2^xi	120.53 (3)	O5^iii—Nb2—Ba2^xxii	57.22 (6)
O2^ix—Sr1—O2^xi	91.02 (5)	Sr1—Nb2—Ba2^xxii	115.437 (8)
O2^x—Sr1—O2^xi	120.53 (3)	Sr1^iii—Nb2—Ba2^xxii	79.30 (1)
O5^ix—Sr1—O2^xi	58.78 (6)	Ba2^xix—Nb2—Ba2^xxii	63.380 (8)
O5^viii—Sr1—O2^xi	60.66 (6)	Sr2^xix—Nb2—Ba2^xxii	63.380 (8)
O5—Sr1—O2^xi	117.95 (7)	Nb2^xxiii—O1—Nb2^xxiv	142.76 (12)
O5^x—Sr1—O2^xi	116.13 (7)	Nb2^xxiii—O1—Ba2	105.70 (9)
O2—Sr1—O2^xii	120.53 (3)	Nb2^xxiv—O1—Ba2	105.70 (9)
O2^viii—Sr1—O2^xii	176.48 (9)	Nb2^xxiii—O1—Ba2^xxv	99.64 (10)
O2^ix—Sr1—O2^xii	120.53 (3)	Nb2^xxiv—O1—Ba2^xxv	99.64 (10)
O2^x—Sr1—O2^xii	91.02 (5)	Ba2—O1—Ba2^xxv	90.43 (6)
O5^ix—Sr1—O2^xii	60.66 (6)	Nb2^xxiii—O1—Sr2^xxv	99.64 (10)
O5^viii—Sr1—O2^xii	117.95 (7)	Nb2^xxiv—O1—Sr2^xxv	99.64 (10)
O5—Sr1—O2^xii	116.13 (7)	Ba2—O1—Sr2^xxv	90.43 (6)
O5^x—Sr1—O2^xii	58.78 (6)	Nb2^xxv—O2—Nb2^xxvi	169.98 (17)
O2^xi—Sr1—O2^xii	57.35 (6)	Nb2^xxv—O2—Sr1	94.83 (8)
O2—Sr1—O2^xiii	120.53 (3)	Nb2^xxvi—O2—Sr1	93.52 (7)
O2^viii—Sr1—O2^xiii	91.02 (5)	Nb2^xxv—O2—Sr1^xxv	87.68 (8)
O2^ix—Sr1—O2^xiii	120.53 (3)	Nb2^xxvi—O2—Sr1^xxv	86.64 (8)
O2^x—Sr1—O2^xiii	176.48 (9)	Sr1—O2—Sr1^xxv	91.02 (5)
O5^ix—Sr1—O2^xiii	116.13 (7)	Nb2^xxv—O2—Ba2^xix	89.46 (7)
O5^viii—Sr1—O2^xiii	58.78 (6)	Nb2^xxvi—O2—Ba2^xix	94.25 (7)
O5—Sr1—O2^xiii	60.66 (6)	Sr1—O2—Ba2^xix	101.82 (9)
O5^x—Sr1—O2^xiii	117.95 (7)	Sr1^xxv—O2—Ba2^xix	167.04 (9)
O2^xi—Sr1—O2^xiii	57.35 (6)	Nb2^xxv—O2—Sr2^xix	89.46 (7)
O2^xii—Sr1—O2^xiii	85.46 (10)	Nb2^xxvi—O2—Sr2^xix	94.25 (7)
O2—Sr1—O2^iii	91.02 (5)	Sr1—O2—Sr2^xix	101.82 (9)
O2^viii—Sr1—O2^iii	120.53 (3)	Sr1^xxv—O2—Sr2^xix	167.04 (9)
O2^ix—Sr1—O2^iii	176.48 (9)	Nb2^xxvii—O3—Nb1^xxviii	144.41 (10)
O2^x—Sr1—O2^iii	120.53 (3)	Nb2^xxvii—O3—Ba2^ii	112.55 (9)
O5^ix—Sr1—O2^iii	117.95 (7)	Nb1^xxviii—O3—Ba2^ii	100.20 (8)
O5^viii—Sr1—O2^iii	116.13 (7)	Nb2^xxvii—O3—Sr2^ii	112.55 (9)
O5—Sr1—O2^iii	58.78 (6)	Nb1^xxviii—O3—Sr2^ii	100.20 (8)
O5^x—Sr1—O2^iii	60.66 (6)	Nb2^xxvii—O3—Sr2^xxix	104.09 (9)
O2^xi—Sr1—O2^iii	85.46 (10)	Nb1^xxviii—O3—Sr2^xxix	90.73 (8)
O2^xii—Sr1—O2^iii	57.35 (6)	Ba2^ii—O3—Sr2^xxix	87.05 (4)
O2^xiii—Sr1—O2^iii	57.35 (6)	Sr2^ii—O3—Sr2^xxix	87.05 (4)
O4—Nb1—O3^xiv	96.58 (9)	Nb2^xxvii—O3—Ba2^xxix	104.09 (9)
O4—Nb1—O3^xv	96.58 (9)	Nb1^xxviii—O3—Ba2^xxix	90.73 (8)
O3^xiv—Nb1—O3^xv	166.83 (18)	Ba2^ii—O3—Ba2^xxix	87.05 (4)
O4—Nb1—O3^xvi	96.58 (9)	Sr2^ii—O3—Ba2^xxix	87.05 (4)
O3^xiv—Nb1—O3^xvi	93.90 (9)	Nb1—O4—Nb1^xxv	180.0
O3^xv—Nb1—O3^xvi	84.59 (9)	Nb1—O4—Sr2^xviii	91.12 (12)
O4—Nb1—O3^xvii	96.58 (9)	Nb1^xxv—O4—Sr2^xviii	88.88 (12)
O3^xiv—Nb1—O3^xvii	84.59 (9)	Nb1—O4—Ba2^xviii	91.12 (12)
O3^xv—Nb1—O3^xvii	93.90 (9)	Nb1^xxv—O4—Ba2^xviii	88.88 (12)
O3^xvi—Nb1—O3^xvii	166.83 (18)	Nb1—O4—Ba2^xix	91.12 (12)
O4—Nb1—O4^iii	180.0	Nb1^xxv—O4—Ba2^xix	88.88 (12)
O3^xiv—Nb1—O4^iii	83.42 (9)	Sr2^xviii—O4—Ba2^xix	177.8 (2)
O3^xv—Nb1—O4^iii	83.42 (9)	Ba2^xviii—O4—Ba2^xix	177.8 (2)
O3^xvi—Nb1—O4^iii	83.42 (9)	Nb1—O4—Sr2^xix	91.12 (12)
O3^xvii—Nb1—O4^iii	83.42 (9)	Nb1^xxv—O4—Sr2^xix	88.88 (12)
O4—Nb1—Ba2^xviii	58.104 (12)	Sr2^xviii—O4—Sr2^xix	177.8 (2)
O3^xiv—Nb1—Ba2^xviii	55.96 (7)	Ba2^xviii—O4—Sr2^xix	177.8 (2)
O3^xv—Nb1—Ba2^xviii	132.92 (6)	Nb2—O5—Nb2^xxv	175.09 (12)
O3^xvi—Nb1—Ba2^xviii	132.92 (6)	Nb2—O5—Sr1	94.21 (8)
O3^xvii—Nb1—Ba2^xviii	55.96 (7)	Nb2^xxv—O5—Sr1	90.04 (8)
O4^iii—Nb1—Ba2^xviii	121.896 (12)	Nb2—O5—Ba2^xix	92.76 (9)
O4—Nb1—Sr2^xviii	58.104 (12)	Nb2^xxv—O5—Ba2^xix	88.69 (8)
O3^xiv—Nb1—Sr2^xviii	55.96 (7)	Sr1—O5—Ba2^xix	102.79 (7)
O3^xv—Nb1—Sr2^xviii	132.92 (6)	Nb2—O5—Sr2^xix	92.76 (9)
O3^xvi—Nb1—Sr2^xviii	132.92 (6)	Nb2^xxv—O5—Sr2^xix	88.69 (8)
O3^xvii—Nb1—Sr2^xviii	55.96 (7)	Sr1—O5—Sr2^xix	102.79 (7)
O4^iii—Nb1—Sr2^xviii	121.896 (12)

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

(shape137)

Crystal data

Ba0.39Nb2O6Sr0.61	Dx = 5.282 Mg m^−3
Mr = 388.68	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4bm	Cell parameters from 8284 reflections
Hall symbol: P 4 -2ab	θ = 3–40°
a = 12.4575 (7) Å	µ = 14.31 mm^−1
c = 3.9382 (3) Å	T = 298 K
V = 611.17 (7) Å^3	Sphere, colourless
Z = 5	0.20 × 0.19 × 0.13 × 0.10 (radius) mm
F(000) = 875.3

Data collection

Xcalibur CCD diffractometer	2096 independent reflections
Radiation source: fine-focus sealed tube	1740 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
ω and ϕ scans	θmax = 39.5°, θmin = 3.3°
Absorption correction: numerical after shape optimisation	h = −20→19
Tmin = 0.130, Tmax = 0.267	k = −21→22
11458 measured reflections	l = −7→7

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0334P)^2 + 0.3182P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.033	(Δ/σ)max = 0.001
wR(F^2) = 0.076	Δρmax = 2.54 e Å^−3
S = 1.14	Δρmin = −3.17 e Å^−3
2096 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
65 parameters	Extinction coefficient: 0.0108 (3)
2 restraints	Absolute structure: Flack H D (1983), 866 Friedel pairs
Primary atom site location: structure-invariant direct methods

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	Occ. (<1)
Ba2	0.17220 (2)	0.67220 (2)	0.49522 (13)	0.02736 (7)	0.4877 (8)
Sr2	0.17220 (2)	0.67220 (2)	0.49522 (13)	0.02736 (7)	0.4037 (8)
Sr1	0.0000	0.0000	0.48961 (18)	0.00856 (10)	0.7180 (12)
Nb1	0.5000	0.0000	0.01794 (12)	0.00900 (6)
Nb2	0.074489 (15)	0.211482 (15)	−0.00035 (8)	0.01067 (3)
O1	0.28227 (15)	0.78227 (15)	0.9698 (10)	0.0189 (6)
O2	0.13869 (17)	0.06946 (15)	0.9619 (9)	0.0316 (7)
O3	0.99311 (16)	0.34320 (15)	0.9664 (10)	0.0357 (7)
O4	0.5000	0.0000	0.4752 (12)	0.0579 (18)
O5	0.0761 (3)	0.2035 (2)	0.4694 (6)	0.0553 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba2	0.03294 (9)	0.03294 (9)	0.01620 (11)	−0.01996 (12)	−0.00053 (17)	−0.00053 (17)
Sr2	0.03294 (9)	0.03294 (9)	0.01620 (11)	−0.01996 (12)	−0.00053 (17)	−0.00053 (17)
Sr1	0.00828 (12)	0.00828 (12)	0.0091 (2)	0.000	0.000	0.000
Nb1	0.00954 (8)	0.00954 (8)	0.00790 (12)	0.00050 (11)	0.000	0.000
Nb2	0.01037 (7)	0.00940 (7)	0.01224 (7)	0.00135 (6)	−0.00012 (15)	−0.00108 (17)
O1	0.0128 (6)	0.0128 (6)	0.0311 (17)	0.0056 (8)	0.0006 (11)	0.0006 (11)
O2	0.0198 (8)	0.0102 (7)	0.0649 (19)	0.0055 (6)	−0.0144 (15)	−0.0115 (14)
O3	0.0188 (9)	0.0094 (7)	0.079 (2)	0.0055 (7)	−0.006 (2)	−0.0099 (15)
O4	0.085 (3)	0.085 (3)	0.0045 (19)	−0.017 (4)	0.000	0.000
O5	0.124 (3)	0.0391 (12)	0.0030 (10)	−0.0406 (14)	0.0047 (13)	0.0007 (10)

Geometric parameters (Å, º)

Ba2—O1	2.693 (3)	Nb1—Sr2^xx	3.6658 (6)
Ba2—O3^i	2.778 (3)	Nb2—O5	1.852 (2)
Ba2—O3^ii	2.778 (3)	Nb2—O3^xxi	1.9335 (19)
Ba2—O1^iii	2.835 (3)	Nb2—O2^iii	1.9475 (19)
Ba2—O3^iv	2.935 (3)	Nb2—O1^xxii	1.9941 (19)
Ba2—O3^v	2.935 (3)	Nb2—O2^xiii	2.0152 (19)
Ba2—O4^vi	3.0351 (4)	Nb2—O5^iii	2.090 (2)
Ba2—O5^vi	3.162 (4)	Nb2—Sr1^iii	3.4400 (6)
Ba2—O5^vii	3.162 (4)	Nb2—Ba2^xix	3.7423 (5)
Ba2—O2^vii	3.250 (3)	Nb2—Sr2^xix	3.7423 (5)
Ba2—O2^vi	3.250 (3)	Nb2—Sr2^xxii	3.7606 (5)
Ba2—Nb1^vi	3.5685 (6)	Nb2—Ba2^xxii	3.7606 (5)
Sr1—O2	2.682 (3)	O1—Nb2^xxiii	1.9941 (19)
Sr1—O2^viii	2.682 (3)	O1—Nb2^xxiv	1.9941 (19)
Sr1—O2^ix	2.682 (3)	O1—Ba2^xxv	2.835 (3)
Sr1—O2^x	2.682 (3)	O1—Sr2^xxv	2.835 (3)
Sr1—O5^ix	2.708 (3)	O2—Nb2^xxv	1.9475 (19)
Sr1—O5^x	2.708 (3)	O2—Nb2^xxvi	2.0152 (19)
Sr1—O5	2.708 (3)	O2—Sr1^xxv	2.837 (3)
Sr1—O5^viii	2.708 (3)	O2—Ba2^xix	3.250 (3)
Sr1—O2^xi	2.837 (3)	O2—Sr2^xix	3.250 (3)
Sr1—O2^xii	2.837 (3)	O3—Nb2^xxvii	1.9335 (19)
Sr1—O2^xiii	2.837 (3)	O3—Nb1^xxviii	1.9659 (19)
Sr1—O2^iii	2.837 (3)	O3—Ba2^i	2.778 (3)
Nb1—O4	1.800 (5)	O3—Sr2^i	2.778 (3)
Nb1—O3^xiv	1.9659 (19)	O3—Sr2^xxix	2.935 (3)
Nb1—O3^xv	1.9659 (19)	O3—Ba2^xxix	2.935 (3)
Nb1—O3^xvi	1.9659 (19)	O4—Nb1^xxv	2.136 (5)
Nb1—O3^xvii	1.9659 (19)	O4—Sr2^xviii	3.0351 (4)
Nb1—O4^iii	2.136 (5)	O4—Ba2^xviii	3.0351 (4)
Nb1—Ba2^xviii	3.5685 (6)	O4—Ba2^xix	3.0351 (4)
Nb1—Sr2^xviii	3.5685 (6)	O4—Sr2^xix	3.0351 (4)
Nb1—Sr2^xix	3.5685 (6)	O5—Nb2^xxv	2.090 (2)
Nb1—Ba2^xix	3.5685 (6)	O5—Ba2^xix	3.162 (4)
Nb1—Ba2^xx	3.6658 (6)	O5—Sr2^xix	3.162 (4)
O1—Ba2—O3^i	87.11 (9)	O4—Nb1—Sr2^xix	58.22 (2)
O1—Ba2—O3^ii	87.11 (9)	O3^xiv—Nb1—Sr2^xix	55.30 (9)
O3^i—Ba2—O3^ii	56.77 (9)	O3^xv—Nb1—Sr2^xix	132.69 (8)
O1—Ba2—O1^iii	90.76 (8)	O3^xvi—Nb1—Sr2^xix	132.69 (8)
O3^i—Ba2—O1^iii	151.51 (4)	O3^xvii—Nb1—Sr2^xix	55.30 (9)
O3^ii—Ba2—O1^iii	151.51 (4)	O4^iii—Nb1—Sr2^xix	121.78 (2)
O1—Ba2—O3^iv	151.98 (4)	Ba2^xviii—Nb1—Sr2^xix	116.44 (3)
O3^i—Ba2—O3^iv	87.06 (6)	Sr2^xviii—Nb1—Sr2^xix	116.44 (3)
O3^ii—Ba2—O3^iv	112.12 (7)	O4—Nb1—Ba2^xix	58.22 (2)
O1^iii—Ba2—O3^iv	81.59 (8)	O3^xiv—Nb1—Ba2^xix	55.30 (9)
O1—Ba2—O3^v	151.98 (4)	O3^xv—Nb1—Ba2^xix	132.69 (8)
O3^i—Ba2—O3^v	112.12 (7)	O3^xvi—Nb1—Ba2^xix	132.69 (8)
O3^ii—Ba2—O3^v	87.06 (6)	O3^xvii—Nb1—Ba2^xix	55.30 (9)
O1^iii—Ba2—O3^v	81.59 (8)	O4^iii—Nb1—Ba2^xix	121.78 (2)
O3^iv—Ba2—O3^v	53.49 (9)	Ba2^xviii—Nb1—Ba2^xix	116.44 (3)
O1—Ba2—O4^vi	137.56 (11)	Sr2^xviii—Nb1—Ba2^xix	116.44 (3)
O3^i—Ba2—O4^vi	56.25 (9)	O4—Nb1—Ba2^xx	124.16 (2)
O3^ii—Ba2—O4^vi	56.25 (9)	O3^xiv—Nb1—Ba2^xx	123.31 (9)
O1^iii—Ba2—O4^vi	131.68 (11)	O3^xv—Nb1—Ba2^xx	48.31 (9)
O3^iv—Ba2—O4^vi	55.89 (9)	O3^xvi—Nb1—Ba2^xx	48.31 (9)
O3^v—Ba2—O4^vi	55.89 (9)	O3^xvii—Nb1—Ba2^xx	123.31 (9)
O1—Ba2—O5^vi	56.93 (7)	O4^iii—Nb1—Ba2^xx	55.84 (2)
O3^i—Ba2—O5^vi	139.94 (8)	Ba2^xviii—Nb1—Ba2^xx	65.94 (2)
O3^ii—Ba2—O5^vi	100.45 (6)	Sr2^xviii—Nb1—Ba2^xx	65.94 (2)
O1^iii—Ba2—O5^vi	55.74 (6)	Sr2^xix—Nb1—Ba2^xx	177.622 (19)
O3^iv—Ba2—O5^vi	132.95 (8)	Ba2^xix—Nb1—Ba2^xx	177.622 (19)
O3^v—Ba2—O5^vi	97.39 (6)	O4—Nb1—Sr2^xx	124.16 (2)
O4^vi—Ba2—O5^vi	141.95 (5)	O3^xiv—Nb1—Sr2^xx	123.31 (9)
O1—Ba2—O5^vii	56.93 (6)	O3^xv—Nb1—Sr2^xx	48.31 (9)
O3^i—Ba2—O5^vii	100.45 (6)	O3^xvi—Nb1—Sr2^xx	48.31 (9)
O3^ii—Ba2—O5^vii	139.94 (8)	O3^xvii—Nb1—Sr2^xx	123.31 (9)
O1^iii—Ba2—O5^vii	55.74 (6)	O4^iii—Nb1—Sr2^xx	55.84 (2)
O3^iv—Ba2—O5^vii	97.39 (6)	Ba2^xviii—Nb1—Sr2^xx	65.94 (2)
O3^v—Ba2—O5^vii	132.95 (8)	Sr2^xviii—Nb1—Sr2^xx	65.94 (2)
O4^vi—Ba2—O5^vii	141.95 (5)	Sr2^xix—Nb1—Sr2^xx	177.622 (19)
O5^vi—Ba2—O5^vii	75.78 (9)	Ba2^xix—Nb1—Sr2^xx	177.622 (19)
O1—Ba2—O2^vii	55.89 (5)	O5—Nb2—O3^xxi	96.82 (15)
O3^i—Ba2—O2^vii	51.74 (6)	O5—Nb2—O2^iii	91.31 (14)
O3^ii—Ba2—O2^vii	97.64 (8)	O3^xxi—Nb2—O2^iii	168.93 (13)
O1^iii—Ba2—O2^vii	104.60 (6)	O5—Nb2—O1^xxii	94.19 (15)
O3^iv—Ba2—O2^vii	99.90 (7)	O3^xxi—Nb2—O1^xxii	95.16 (9)
O3^v—Ba2—O2^vii	152.12 (5)	O2^iii—Nb2—O1^xxii	91.70 (9)
O4^vi—Ba2—O2^vii	104.40 (6)	O5—Nb2—O2^xiii	93.37 (14)
O5^vi—Ba2—O2^vii	108.63 (6)	O3^xxi—Nb2—O2^xiii	84.85 (8)
O5^vii—Ba2—O2^vii	49.29 (6)	O2^iii—Nb2—O2^xiii	87.19 (12)
O1—Ba2—O2^vi	55.89 (5)	O1^xxii—Nb2—O2^xiii	172.39 (14)
O3^i—Ba2—O2^vi	97.64 (8)	O5—Nb2—O5^iii	174.08 (16)
O3^ii—Ba2—O2^vi	51.74 (6)	O3^xxi—Nb2—O5^iii	88.72 (14)
O1^iii—Ba2—O2^vi	104.60 (6)	O2^iii—Nb2—O5^iii	82.92 (13)
O3^iv—Ba2—O2^vi	152.12 (5)	O1^xxii—Nb2—O5^iii	87.36 (13)
O3^v—Ba2—O2^vi	99.90 (7)	O2^xiii—Nb2—O5^iii	85.03 (13)
O4^vi—Ba2—O2^vi	104.40 (6)	O5—Nb2—Sr1	52.69 (8)
O5^vi—Ba2—O2^vi	49.29 (6)	O3^xxi—Nb2—Sr1	123.64 (9)
O5^vii—Ba2—O2^vi	108.63 (6)	O2^iii—Nb2—Sr1	56.66 (9)
O2^vii—Ba2—O2^vi	104.57 (10)	O1^xxii—Nb2—Sr1	128.42 (9)
O1—Ba2—Nb1^vi	167.84 (7)	O2^xiii—Nb2—Sr1	56.58 (9)
O3^i—Ba2—Nb1^vi	82.19 (6)	O5^iii—Nb2—Sr1	122.21 (7)
O3^ii—Ba2—Nb1^vi	82.19 (6)	O5—Nb2—Sr1^iii	122.98 (8)
O1^iii—Ba2—Nb1^vi	101.40 (7)	O3^xxi—Nb2—Sr1^iii	117.98 (9)
O3^iv—Ba2—Nb1^vi	33.42 (4)	O2^iii—Nb2—Sr1^iii	50.98 (8)
O3^v—Ba2—Nb1^vi	33.42 (4)	O1^xxii—Nb2—Sr1^iii	123.08 (9)
O4^vi—Ba2—Nb1^vi	30.28 (9)	O2^xiii—Nb2—Sr1^iii	51.11 (8)
O5^vi—Ba2—Nb1^vi	130.81 (5)	O5^iii—Nb2—Sr1^iii	51.92 (7)
O5^vii—Ba2—Nb1^vi	130.81 (5)	Sr1—Nb2—Sr1^iii	70.36 (3)
O2^vii—Ba2—Nb1^vi	119.77 (4)	O5—Nb2—Ba2^xix	57.56 (11)
O2^vi—Ba2—Nb1^vi	119.77 (4)	O3^xxi—Nb2—Ba2^xix	126.05 (8)
O2—Sr1—O2^viii	61.27 (7)	O2^iii—Nb2—Ba2^xix	64.82 (8)
O2—Sr1—O2^ix	92.22 (13)	O1^xxii—Nb2—Ba2^xix	48.22 (9)
O2^viii—Sr1—O2^ix	61.27 (7)	O2^xiii—Nb2—Ba2^xix	136.89 (8)
O2—Sr1—O2^x	61.27 (7)	O5^iii—Nb2—Ba2^xix	120.43 (10)
O2^viii—Sr1—O2^x	92.22 (13)	Sr1—Nb2—Ba2^xix	80.36 (2)
O2^ix—Sr1—O2^x	61.27 (7)	Sr1^iii—Nb2—Ba2^xix	115.58 (2)
O2—Sr1—O5^ix	123.24 (8)	O5—Nb2—Sr2^xix	57.56 (11)
O2^viii—Sr1—O5^ix	120.72 (8)	O3^xxi—Nb2—Sr2^xix	126.05 (8)
O2^ix—Sr1—O5^ix	59.52 (8)	O2^iii—Nb2—Sr2^xix	64.82 (8)
O2^x—Sr1—O5^ix	61.97 (8)	O1^xxii—Nb2—Sr2^xix	48.22 (9)
O2—Sr1—O5^x	61.97 (8)	O2^xiii—Nb2—Sr2^xix	136.89 (8)
O2^viii—Sr1—O5^x	123.24 (8)	O5^iii—Nb2—Sr2^xix	120.43 (10)
O2^ix—Sr1—O5^x	120.72 (8)	Sr1—Nb2—Sr2^xix	80.36 (2)
O2^x—Sr1—O5^x	59.52 (8)	Sr1^iii—Nb2—Sr2^xix	115.58 (2)
O5^ix—Sr1—O5^x	89.950 (3)	O5—Nb2—Sr2^xxii	120.75 (11)
O2—Sr1—O5	59.52 (8)	O3^xxi—Nb2—Sr2^xxii	120.98 (9)
O2^viii—Sr1—O5	61.97 (8)	O2^iii—Nb2—Sr2^xxii	59.79 (8)
O2^ix—Sr1—O5	123.24 (8)	O1^xxii—Nb2—Sr2^xxii	43.57 (9)
O2^x—Sr1—O5	120.72 (8)	O2^xiii—Nb2—Sr2^xxii	130.50 (8)
O5^ix—Sr1—O5	176.63 (10)	O5^iii—Nb2—Sr2^xxii	57.22 (10)
O5^x—Sr1—O5	89.950 (3)	Sr1—Nb2—Sr2^xxii	115.38 (2)
O2—Sr1—O5^viii	120.72 (8)	Sr1^iii—Nb2—Sr2^xxii	79.53 (2)
O2^viii—Sr1—O5^viii	59.52 (8)	Ba2^xix—Nb2—Sr2^xxii	63.32 (3)
O2^ix—Sr1—O5^viii	61.97 (8)	Sr2^xix—Nb2—Sr2^xxii	63.32 (3)
O2^x—Sr1—O5^viii	123.24 (8)	O5—Nb2—Ba2^xxii	120.75 (11)
O5^ix—Sr1—O5^viii	89.950 (3)	O3^xxi—Nb2—Ba2^xxii	120.98 (9)
O5^x—Sr1—O5^viii	176.63 (10)	O2^iii—Nb2—Ba2^xxii	59.79 (8)
O5—Sr1—O5^viii	89.950 (3)	O1^xxii—Nb2—Ba2^xxii	43.57 (9)
O2—Sr1—O2^xi	176.83 (10)	O2^xiii—Nb2—Ba2^xxii	130.50 (8)
O2^viii—Sr1—O2^xi	120.50 (4)	O5^iii—Nb2—Ba2^xxii	57.22 (10)
O2^ix—Sr1—O2^xi	90.95 (6)	Sr1—Nb2—Ba2^xxii	115.38 (2)
O2^x—Sr1—O2^xi	120.50 (4)	Sr1^iii—Nb2—Ba2^xxii	79.53 (2)
O5^ix—Sr1—O2^xi	58.65 (7)	Ba2^xix—Nb2—Ba2^xxii	63.32 (3)
O5^x—Sr1—O2^xi	116.23 (8)	Sr2^xix—Nb2—Ba2^xxii	63.32 (3)
O5—Sr1—O2^xi	118.50 (7)	Nb2^xxiii—O1—Nb2^xxiv	142.01 (14)
O5^viii—Sr1—O2^xi	60.98 (8)	Nb2^xxiii—O1—Ba2	105.75 (10)
O2—Sr1—O2^xii	120.50 (4)	Nb2^xxiv—O1—Ba2	105.75 (10)
O2^viii—Sr1—O2^xii	176.83 (10)	Nb2^xxiii—O1—Ba2^xxv	100.14 (10)
O2^ix—Sr1—O2^xii	120.50 (4)	Nb2^xxiv—O1—Ba2^xxv	100.14 (10)
O2^x—Sr1—O2^xii	90.95 (6)	Ba2—O1—Ba2^xxv	90.76 (8)
O5^ix—Sr1—O2^xii	60.98 (8)	Nb2^xxiii—O1—Sr2^xxv	100.14 (10)
O5^x—Sr1—O2^xii	58.65 (7)	Nb2^xxiv—O1—Sr2^xxv	100.14 (10)
O5—Sr1—O2^xii	116.23 (8)	Ba2—O1—Sr2^xxv	90.76 (8)
O5^viii—Sr1—O2^xii	118.50 (7)	Nb2^xxv—O2—Nb2^xxvi	171.05 (19)
O2^xi—Sr1—O2^xii	57.59 (7)	Nb2^xxv—O2—Sr1	94.67 (9)
O2—Sr1—O2^xiii	120.50 (4)	Nb2^xxvi—O2—Sr1	93.09 (8)
O2^viii—Sr1—O2^xiii	90.95 (6)	Nb2^xxv—O2—Sr1^xxv	88.35 (10)
O2^ix—Sr1—O2^xiii	120.50 (4)	Nb2^xxvi—O2—Sr1^xxv	87.06 (9)
O2^x—Sr1—O2^xiii	176.83 (10)	Sr1—O2—Sr1^xxv	90.95 (6)
O5^ix—Sr1—O2^xiii	116.23 (8)	Nb2^xxv—O2—Ba2^xix	89.03 (8)
O5^x—Sr1—O2^xiii	118.50 (7)	Nb2^xxvi—O2—Ba2^xix	93.78 (9)
O5—Sr1—O2^xiii	60.98 (8)	Sr1—O2—Ba2^xix	101.67 (11)
O5^viii—Sr1—O2^xiii	58.65 (7)	Sr1^xxv—O2—Ba2^xix	167.27 (11)
O2^xi—Sr1—O2^xiii	57.59 (7)	Nb2^xxv—O2—Sr2^xix	89.03 (8)
O2^xii—Sr1—O2^xiii	85.88 (11)	Nb2^xxvi—O2—Sr2^xix	93.78 (9)
O2—Sr1—O2^iii	90.95 (6)	Sr1—O2—Sr2^xix	101.67 (11)
O2^viii—Sr1—O2^iii	120.50 (4)	Sr1^xxv—O2—Sr2^xix	167.27 (11)
O2^ix—Sr1—O2^iii	176.83 (10)	Nb2^xxvii—O3—Nb1^xxviii	144.44 (12)
O2^x—Sr1—O2^iii	120.50 (4)	Nb2^xxvii—O3—Ba2^i	112.05 (11)
O5^ix—Sr1—O2^iii	118.50 (7)	Nb1^xxviii—O3—Ba2^i	99.78 (10)
O5^x—Sr1—O2^iii	60.98 (8)	Nb2^xxvii—O3—Sr2^i	112.05 (11)
O5—Sr1—O2^iii	58.64 (7)	Nb1^xxviii—O3—Sr2^i	99.78 (10)
O5^viii—Sr1—O2^iii	116.23 (8)	Nb2^xxvii—O3—Sr2^xxix	105.34 (12)
O2^xi—Sr1—O2^iii	85.88 (11)	Nb1^xxviii—O3—Sr2^xxix	91.28 (10)
O2^xii—Sr1—O2^iii	57.59 (7)	Ba2^i—O3—Sr2^xxix	87.06 (6)
O2^xiii—Sr1—O2^iii	57.59 (7)	Sr2^i—O3—Sr2^xxix	87.06 (6)
O4—Nb1—O3^xiv	95.93 (11)	Nb2^xxvii—O3—Ba2^xxix	105.34 (12)
O4—Nb1—O3^xv	95.93 (11)	Nb1^xxviii—O3—Ba2^xxix	91.28 (10)
O3^xiv—Nb1—O3^xv	94.36 (12)	Ba2^i—O3—Ba2^xxix	87.06 (6)
O4—Nb1—O3^xvi	95.93 (11)	Sr2^i—O3—Ba2^xxix	87.06 (6)
O3^xiv—Nb1—O3^xvi	168.1 (2)	Nb1—O4—Nb1^xxv	180.0
O3^xv—Nb1—O3^xvi	84.41 (12)	Nb1—O4—Sr2^xviii	91.49 (9)
O4—Nb1—O3^xvii	95.93 (11)	Nb1^xxv—O4—Sr2^xviii	88.51 (9)
O3^xiv—Nb1—O3^xvii	84.41 (12)	Nb1—O4—Ba2^xviii	91.49 (9)
O3^xv—Nb1—O3^xvii	168.1 (2)	Nb1^xxv—O4—Ba2^xviii	88.51 (9)
O3^xvi—Nb1—O3^xvii	94.36 (12)	Nb1—O4—Ba2^xix	91.49 (9)
O4—Nb1—O4^iii	180.0	Nb1^xxv—O4—Ba2^xix	88.51 (9)
O3^xiv—Nb1—O4^iii	84.07 (11)	Sr2^xviii—O4—Ba2^xix	177.02 (18)
O3^xv—Nb1—O4^iii	84.07 (11)	Ba2^xviii—O4—Ba2^xix	177.02 (18)
O3^xvi—Nb1—O4^iii	84.07 (11)	Nb1—O4—Sr2^xix	91.49 (9)
O3^xvii—Nb1—O4^iii	84.07 (11)	Nb1^xxv—O4—Sr2^xix	88.51 (9)
O4—Nb1—Ba2^xviii	58.22 (4)	Sr2^xviii—O4—Sr2^xix	177.02 (18)
O3^xiv—Nb1—Ba2^xviii	132.69 (8)	Ba2^xviii—O4—Sr2^xix	177.02 (18)
O3^xv—Nb1—Ba2^xviii	55.30 (9)	Nb2—O5—Nb2^xxv	174.08 (16)
O3^xvi—Nb1—Ba2^xviii	55.30 (9)	Nb2—O5—Sr1	94.36 (10)
O3^xvii—Nb1—Ba2^xviii	132.69 (8)	Nb2^xxv—O5—Sr1	90.68 (9)
O4^iii—Nb1—Ba2^xviii	121.78 (2)	Nb2—O5—Ba2^xix	92.83 (12)
O4—Nb1—Sr2^xviii	58.22 (2)	Nb2^xxv—O5—Ba2^xix	89.03 (10)
O3^xiv—Nb1—Sr2^xviii	132.69 (8)	Sr1—O5—Ba2^xix	103.34 (10)
O3^xv—Nb1—Sr2^xviii	55.30 (9)	Nb2—O5—Sr2^xix	92.83 (12)
O3^xvi—Nb1—Sr2^xviii	55.30 (9)	Nb2^xxv—O5—Sr2^xix	89.03 (10)
O3^xvii—Nb1—Sr2^xviii	132.69 (8)	Sr1—O5—Sr2^xix	103.34 (10)
O4^iii—Nb1—Sr2^xviii	121.78 (2)

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

(sbn159k3)

Crystal data

Ba0.14Nb2O6Sr0.86	Dx = 5.216 Mg m^−3
Mr = 378.29	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4bm	Cell parameters from 5511 reflections
Hall symbol: P 4 -2ab	θ = 3–40°
a = 12.4179 (9) Å	µ = 15.13 mm^−1
c = 3.9074 (5) Å	T = 298 K
V = 602.54 (10) Å^3	Sphere, colourless
Z = 5	0.17 × 0.17 × 0.12 × 0.09 (radius) mm
F(000) = 852.8

Data collection

Xcalibur CCD diffractometer	2153 independent reflections
Radiation source: fine-focus sealed tube	1365 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.060
ω and ϕ scans	θmax = 43.3°, θmin = 3.3°
Absorption correction: numerical after shape optimisation	h = −22→22
Tmin = 0.099, Tmax = 0.169	k = −19→23
11273 measured reflections	l = −7→7

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0383P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.045	(Δ/σ)max = 0.010
wR(F^2) = 0.091	Δρmax = 3.63 e Å^−3
S = 0.96	Δρmin = −3.54 e Å^−3
2153 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
65 parameters	Extinction coefficient: 0.0118 (4)
2 restraints	Absolute structure: Flack H D (1983), 891 Friedel pairs
Primary atom site location: structure-invariant direct methods

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	Occ. (<1)
Ba2	0.17232 (3)	0.67232 (3)	0.5066 (3)	0.03420 (13)	0.1782 (12)
Sr2	0.17232 (3)	0.67232 (3)	0.5066 (3)	0.03420 (13)	0.7289 (11)
Sr1	0.0000	0.0000	0.4976 (5)	0.00966 (15)	0.6859 (16)
Nb1	0.5000	0.0000	0.0010 (4)	0.01894 (12)
Nb2	0.07479 (2)	0.21140 (2)	−0.0023 (2)	0.01436 (6)
O1	0.2813 (2)	0.7813 (2)	0.9636 (15)	0.0203 (10)
O2	0.1384 (2)	0.0678 (2)	1.007 (2)	0.0458 (10)
O3	0.9938 (2)	0.3428 (2)	0.9287 (7)	0.0216 (8)
O4	0.5000	0.0000	0.469 (2)	0.084 (3)
O5	0.0779 (4)	0.2051 (3)	0.4753 (14)	0.0791 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba2	0.04138 (18)	0.04138 (18)	0.0198 (2)	−0.0254 (2)	0.0046 (3)	0.0046 (3)
Sr2	0.04138 (18)	0.04138 (18)	0.0198 (2)	−0.0254 (2)	0.0046 (3)	0.0046 (3)
Sr1	0.00889 (19)	0.00889 (19)	0.0112 (3)	0.000	0.000	0.000
Nb1	0.01085 (13)	0.01085 (13)	0.0351 (3)	0.00078 (19)	0.000	0.000
Nb2	0.01269 (11)	0.01132 (11)	0.01907 (11)	0.00162 (9)	−0.0037 (3)	0.0047 (3)
O1	0.0132 (9)	0.0132 (9)	0.034 (3)	0.0065 (12)	−0.0077 (16)	−0.0077 (16)
O2	0.0198 (12)	0.0147 (11)	0.103 (3)	0.0041 (10)	0.023 (4)	−0.010 (4)
O3	0.0235 (13)	0.0095 (11)	0.032 (2)	0.0045 (10)	−0.0058 (12)	0.0001 (10)
O4	0.122 (5)	0.122 (5)	0.006 (4)	−0.034 (6)	0.000	0.000
O5	0.172 (4)	0.062 (2)	0.0035 (14)	−0.067 (2)	0.014 (3)	−0.009 (2)

Geometric parameters (Å, º)

Ba2—O1	2.616 (5)	Nb1—Ba2^xxi	3.6134 (11)
Ba2—O3^i	2.647 (3)	Nb2—O5	1.866 (5)
Ba2—O3^ii	2.647 (3)	Nb2—O3^xxii	1.936 (3)
Ba2—O1^iii	2.856 (5)	Nb2—O2^iii	1.950 (3)
Ba2—O4^iv	3.0303 (8)	Nb2—O2^xi	1.990 (3)
Ba2—O3^v	3.063 (3)	Nb2—O1^xix	1.992 (2)
Ba2—O3^vi	3.063 (3)	Nb2—O5^iii	2.042 (5)
Ba2—O5^vii	3.131 (5)	Nb2—Sr1^iii	3.4012 (12)
Ba2—O5^iv	3.131 (5)	Nb2—Ba2^xix	3.7116 (8)
Ba2—O2^viii	3.318 (6)	Nb2—Sr2^xix	3.7116 (8)
Ba2—O2^ix	3.318 (6)	Nb2—Sr2^xxi	3.7479 (8)
Ba2—O2^vii	3.321 (5)	Nb2—Ba2^xxi	3.7479 (8)
Sr1—O2^x	2.707 (7)	O1—Nb2^xxiii	1.992 (2)
Sr1—O2^xi	2.707 (7)	O1—Nb2^xxiv	1.992 (2)
Sr1—O2^xii	2.707 (7)	O1—Ba2^xxv	2.856 (5)
Sr1—O2^iii	2.707 (7)	O1—Sr2^xxv	2.856 (5)
Sr1—O5^xiii	2.726 (4)	O2—Nb2^xxv	1.950 (3)
Sr1—O5	2.726 (4)	O2—Nb2^xxvi	1.990 (3)
Sr1—O5^xiv	2.726 (4)	O2—Sr1^xxv	2.707 (7)
Sr1—O5^xv	2.726 (4)	O2—Ba2^xxvii	3.318 (6)
Sr1—O2^xiv	2.761 (7)	O2—Ba2^xxi	3.321 (5)
Sr1—O2^xv	2.761 (7)	O3—Nb2^xxviii	1.936 (3)
Sr1—O2	2.761 (7)	O3—Nb1^xxix	1.974 (3)
Sr1—O2^xiii	2.761 (7)	O3—Ba2^ii	2.647 (3)
Nb1—O4	1.826 (9)	O3—Sr2^ii	2.647 (3)
Nb1—O3^xvi	1.974 (3)	O3—Sr2^xxx	3.063 (3)
Nb1—O3^xvii	1.974 (3)	O3—Ba2^xxx	3.063 (3)
Nb1—O3^xviii	1.974 (3)	O4—Nb1^xxv	2.078 (9)
Nb1—O3^viii	1.974 (3)	O4—Ba2^xxi	3.0303 (7)
Nb1—O4^iii	2.078 (9)	O4—Ba2^xxxi	3.0303 (7)
Nb1—Sr2^xix	3.5898 (11)	O4—Sr2^xxi	3.0303 (7)
Nb1—Ba2^xx	3.5898 (11)	O4—Sr2^xxxi	3.0303 (7)
Nb1—Sr2^xx	3.5898 (11)	O5—Nb2^xxv	2.042 (5)
Nb1—Ba2^xix	3.5898 (11)	O5—Ba2^xxi	3.131 (5)
Nb1—Sr2^xxi	3.6134 (11)	O5—Sr2^xxi	3.131 (5)
O1—Ba2—O3^i	90.87 (12)	Sr2^xix—Nb1—Ba2^xx	114.95 (5)
O1—Ba2—O3^ii	90.88 (12)	O4—Nb1—Sr2^xx	122.53 (3)
O3^i—Ba2—O3^ii	60.10 (11)	O3^xvi—Nb1—Sr2^xx	46.39 (8)
O1—Ba2—O1^iii	90.94 (11)	O3^xvii—Nb1—Sr2^xx	122.41 (9)
O3^i—Ba2—O1^iii	149.89 (6)	O3^xviii—Nb1—Sr2^xx	46.39 (8)
O3^ii—Ba2—O1^iii	149.89 (6)	O3^viii—Nb1—Sr2^xx	122.41 (9)
O1—Ba2—O4^iv	139.8 (2)	O4^iii—Nb1—Sr2^xx	57.47 (3)
O3^i—Ba2—O4^iv	55.23 (15)	Sr2^xix—Nb1—Sr2^xx	114.95 (5)
O3^ii—Ba2—O4^iv	55.23 (15)	O4—Nb1—Ba2^xix	122.53 (3)
O1^iii—Ba2—O4^iv	129.27 (19)	O3^xvi—Nb1—Ba2^xix	122.41 (9)
O1—Ba2—O3^v	151.94 (6)	O3^xvii—Nb1—Ba2^xix	46.39 (8)
O3^i—Ba2—O3^v	85.94 (8)	O3^xviii—Nb1—Ba2^xix	122.41 (9)
O3^ii—Ba2—O3^v	111.26 (10)	O3^viii—Nb1—Ba2^xix	46.39 (8)
O1^iii—Ba2—O3^v	78.55 (10)	O4^iii—Nb1—Ba2^xix	57.47 (3)
O4^iv—Ba2—O3^v	56.28 (15)	Ba2^xx—Nb1—Ba2^xix	114.95 (5)
O1—Ba2—O3^vi	151.94 (6)	Sr2^xx—Nb1—Ba2^xix	114.95 (5)
O3^i—Ba2—O3^vi	111.26 (10)	O4—Nb1—Sr2^xxi	56.89 (3)
O3^ii—Ba2—O3^vi	85.94 (8)	O3^xvi—Nb1—Sr2^xxi	133.39 (9)
O1^iii—Ba2—O3^vi	78.55 (10)	O3^xvii—Nb1—Sr2^xxi	57.95 (9)
O4^iv—Ba2—O3^vi	56.28 (15)	O3^xviii—Nb1—Sr2^xxi	133.39 (9)
O3^v—Ba2—O3^vi	51.29 (10)	O3^viii—Nb1—Sr2^xxi	57.94 (9)
O1—Ba2—O5^vii	56.43 (12)	O4^iii—Nb1—Sr2^xxi	123.11 (3)
O3^i—Ba2—O5^vii	143.68 (12)	Sr2^xix—Nb1—Sr2^xxi	65.69 (2)
O3^ii—Ba2—O5^vii	101.31 (10)	Ba2^xx—Nb1—Sr2^xxi	179.42 (5)
O1^iii—Ba2—O5^vii	55.95 (12)	Sr2^xx—Nb1—Sr2^xxi	179.42 (5)
O4^iv—Ba2—O5^vii	142.15 (7)	Ba2^xix—Nb1—Sr2^xxi	65.69 (2)
O3^v—Ba2—O5^vii	130.29 (12)	O4—Nb1—Ba2^xxi	56.89 (3)
O3^vi—Ba2—O5^vii	96.88 (10)	O3^xvi—Nb1—Ba2^xxi	133.39 (9)
O1—Ba2—O5^iv	56.43 (12)	O3^xvii—Nb1—Ba2^xxi	57.95 (9)
O3^i—Ba2—O5^iv	101.31 (10)	O3^xviii—Nb1—Ba2^xxi	133.39 (9)
O3^ii—Ba2—O5^iv	143.68 (12)	O3^viii—Nb1—Ba2^xxi	57.94 (9)
O1^iii—Ba2—O5^iv	55.95 (12)	O4^iii—Nb1—Ba2^xxi	123.11 (3)
O4^iv—Ba2—O5^iv	142.15 (7)	Sr2^xix—Nb1—Ba2^xxi	65.69 (2)
O3^v—Ba2—O5^iv	96.88 (10)	Ba2^xx—Nb1—Ba2^xxi	179.42 (5)
O3^vi—Ba2—O5^iv	130.29 (12)	Sr2^xx—Nb1—Ba2^xxi	179.42 (5)
O5^vii—Ba2—O5^iv	74.98 (14)	Ba2^xix—Nb1—Ba2^xxi	65.69 (2)
O1—Ba2—O2^viii	103.69 (11)	O5—Nb2—O3^xxii	100.66 (17)
O3^i—Ba2—O2^viii	152.88 (8)	O5—Nb2—O2^iii	86.2 (3)
O3^ii—Ba2—O2^viii	96.39 (11)	O3^xxii—Nb2—O2^iii	169.7 (2)
O1^iii—Ba2—O2^viii	54.09 (9)	O5—Nb2—O2^xi	88.9 (3)
O4^iv—Ba2—O2^viii	101.27 (11)	O3^xxii—Nb2—O2^xi	85.66 (12)
O3^v—Ba2—O2^viii	91.17 (13)	O2^iii—Nb2—O2^xi	86.78 (16)
O3^vi—Ba2—O2^viii	49.26 (9)	O5—Nb2—O1^xix	93.8 (2)
O5^vii—Ba2—O2^viii	47.62 (12)	O3^xxii—Nb2—O1^xix	95.15 (13)
O5^iv—Ba2—O2^viii	105.81 (10)	O2^iii—Nb2—O1^xix	92.05 (12)
O1—Ba2—O2^ix	103.68 (11)	O2^xi—Nb2—O1^xix	177.0 (3)
O3^i—Ba2—O2^ix	96.40 (11)	O5—Nb2—O5^iii	174.9 (3)
O3^ii—Ba2—O2^ix	152.88 (8)	O3^xxii—Nb2—O5^iii	84.44 (16)
O1^iii—Ba2—O2^ix	54.09 (9)	O2^iii—Nb2—O5^iii	88.6 (3)
O4^iv—Ba2—O2^ix	101.27 (11)	O2^xi—Nb2—O5^iii	91.0 (3)
O3^v—Ba2—O2^ix	49.26 (9)	O1^xix—Nb2—O5^iii	86.2 (2)
O3^vi—Ba2—O2^ix	91.17 (13)	O5—Nb2—Sr1^iii	123.14 (12)
O5^vii—Ba2—O2^ix	105.81 (10)	O3^xxii—Nb2—Sr1^iii	115.41 (9)
O5^iv—Ba2—O2^ix	47.62 (12)	O2^iii—Nb2—Sr1^iii	54.3 (2)
O2^viii—Ba2—O2^ix	102.1 (2)	O2^xi—Nb2—Sr1^iii	54.27 (19)
O1—Ba2—O2^vii	55.57 (8)	O1^xix—Nb2—Sr1^iii	122.88 (13)
O3^i—Ba2—O2^vii	99.06 (13)	O5^iii—Nb2—Sr1^iii	53.27 (10)
O3^ii—Ba2—O2^vii	51.64 (9)	O5—Nb2—Sr1	53.13 (12)
O1^iii—Ba2—O2^vii	106.66 (11)	O3^xxii—Nb2—Sr1	126.07 (9)
O4^iv—Ba2—O2^vii	104.63 (11)	O2^iii—Nb2—Sr1	52.70 (18)
O3^v—Ba2—O2^vii	152.40 (9)	O2^xi—Nb2—Sr1	52.73 (18)
O3^vi—Ba2—O2^vii	102.35 (11)	O1^xix—Nb2—Sr1	128.31 (14)
O5^vii—Ba2—O2^vii	51.14 (13)	O5^iii—Nb2—Sr1	123.29 (10)
O5^iv—Ba2—O2^vii	108.55 (9)	Sr1^iii—Nb2—Sr1	70.11 (4)
O2^viii—Ba2—O2^vii	72.04 (6)	O5—Nb2—Ba2^xix	119.55 (17)
O2^ix—Ba2—O2^vii	154.08 (9)	O3^xxii—Nb2—Ba2^xix	118.55 (9)
O2^x—Sr1—O2^xi	90.0 (3)	O2^iii—Nb2—Ba2^xix	63.10 (16)
O2^x—Sr1—O2^xii	60.00 (17)	O2^xi—Nb2—Ba2^xix	134.69 (19)
O2^xi—Sr1—O2^xii	60.00 (17)	O1^xix—Nb2—Ba2^xix	42.50 (13)
O2^x—Sr1—O2^iii	60.00 (17)	O5^iii—Nb2—Ba2^xix	57.52 (15)
O2^xi—Sr1—O2^iii	60.00 (17)	Sr1^iii—Nb2—Ba2^xix	80.39 (3)
O2^xii—Sr1—O2^iii	90.0 (3)	Sr1—Nb2—Ba2^xix	115.28 (2)
O2^x—Sr1—O5^xiii	59.64 (15)	O5—Nb2—Sr2^xix	119.55 (17)
O2^xi—Sr1—O5^xiii	117.40 (16)	O3^xxii—Nb2—Sr2^xix	118.55 (9)
O2^xii—Sr1—O5^xiii	57.41 (14)	O2^iii—Nb2—Sr2^xix	63.10 (16)
O2^iii—Sr1—O5^xiii	119.57 (16)	O2^xi—Nb2—Sr2^xix	134.69 (19)
O2^x—Sr1—O5	117.40 (16)	O1^xix—Nb2—Sr2^xix	42.50 (13)
O2^xi—Sr1—O5	59.64 (15)	O5^iii—Nb2—Sr2^xix	57.52 (15)
O2^xii—Sr1—O5	119.57 (16)	Sr1^iii—Nb2—Sr2^xix	80.39 (3)
O2^iii—Sr1—O5	57.41 (14)	Sr1—Nb2—Sr2^xix	115.28 (2)
O5^xiii—Sr1—O5	176.3 (2)	O5—Nb2—Sr2^xxi	56.49 (16)
O2^x—Sr1—O5^xiv	119.57 (16)	O3^xxii—Nb2—Sr2^xxi	128.19 (8)
O2^xi—Sr1—O5^xiv	57.41 (14)	O2^iii—Nb2—Sr2^xxi	62.10 (17)
O2^xii—Sr1—O5^xiv	59.64 (15)	O2^xi—Nb2—Sr2^xxi	132.61 (19)
O2^iii—Sr1—O5^xiv	117.41 (16)	O1^xix—Nb2—Sr2^xxi	48.67 (15)
O5^xiii—Sr1—O5^xiv	89.940 (8)	O5^iii—Nb2—Sr2^xxi	120.59 (15)
O5—Sr1—O5^xiv	89.943 (8)	Sr1^iii—Nb2—Sr2^xxi	115.672 (15)
O2^x—Sr1—O5^xv	57.41 (14)	Sr1—Nb2—Sr2^xxi	79.88 (3)
O2^xi—Sr1—O5^xv	119.57 (16)	Ba2^xix—Nb2—Sr2^xxi	63.16 (2)
O2^xii—Sr1—O5^xv	117.41 (16)	Sr2^xix—Nb2—Sr2^xxi	63.16 (2)
O2^iii—Sr1—O5^xv	59.64 (15)	O5—Nb2—Ba2^xxi	56.49 (16)
O5^xiii—Sr1—O5^xv	89.943 (8)	O3^xxii—Nb2—Ba2^xxi	128.19 (8)
O5—Sr1—O5^xv	89.940 (8)	O2^iii—Nb2—Ba2^xxi	62.10 (17)
O5^xiv—Sr1—O5^xv	176.3 (2)	O2^xi—Nb2—Ba2^xxi	132.61 (19)
O2^x—Sr1—O2^xiv	178.9 (3)	O1^xix—Nb2—Ba2^xxi	48.67 (15)
O2^xi—Sr1—O2^xiv	91.11 (8)	O5^iii—Nb2—Ba2^xxi	120.59 (15)
O2^xii—Sr1—O2^xiv	120.63 (5)	Sr1^iii—Nb2—Ba2^xxi	115.672 (15)
O2^iii—Sr1—O2^xiv	120.64 (5)	Sr1—Nb2—Ba2^xxi	79.88 (3)
O5^xiii—Sr1—O2^xiv	119.77 (15)	Ba2^xix—Nb2—Ba2^xxi	63.16 (2)
O5—Sr1—O2^xiv	63.23 (14)	Sr2^xix—Nb2—Ba2^xxi	63.16 (2)
O5^xiv—Sr1—O2^xiv	61.12 (15)	Nb2^xxiii—O1—Nb2^xxiv	141.03 (19)
O5^xv—Sr1—O2^xiv	121.94 (16)	Nb2^xxiii—O1—Ba2	106.54 (14)
O2^x—Sr1—O2^xv	91.11 (8)	Nb2^xxiv—O1—Ba2	106.54 (14)
O2^xi—Sr1—O2^xv	178.9 (3)	Nb2^xxiii—O1—Ba2^xxv	99.74 (16)
O2^xii—Sr1—O2^xv	120.64 (5)	Nb2^xxiv—O1—Ba2^xxv	99.74 (16)
O2^iii—Sr1—O2^xv	120.63 (5)	Ba2—O1—Ba2^xxv	90.94 (11)
O5^xiii—Sr1—O2^xv	63.23 (14)	Nb2^xxiii—O1—Sr2^xxv	99.74 (16)
O5—Sr1—O2^xv	119.77 (15)	Nb2^xxiv—O1—Sr2^xxv	99.74 (16)
O5^xiv—Sr1—O2^xv	121.94 (16)	Ba2—O1—Sr2^xxv	90.94 (11)
O5^xv—Sr1—O2^xv	61.12 (15)	Nb2^xxv—O2—Nb2^xxvi	176.1 (3)
O2^xiv—Sr1—O2^xv	87.8 (3)	Nb2^xxv—O2—Sr1^xxv	92.34 (19)
O2^x—Sr1—O2	120.63 (5)	Nb2^xxvi—O2—Sr1^xxv	91.46 (19)
O2^xi—Sr1—O2	120.64 (5)	Nb2^xxv—O2—Sr1	90.7 (2)
O2^xii—Sr1—O2	178.9 (3)	Nb2^xxvi—O2—Sr1	89.91 (19)
O2^iii—Sr1—O2	91.11 (8)	Sr1^xxv—O2—Sr1	91.11 (8)
O5^xiii—Sr1—O2	121.94 (16)	Nb2^xxv—O2—Ba2^xxvii	86.60 (16)
O5—Sr1—O2	61.12 (15)	Nb2^xxvi—O2—Ba2^xxvii	92.08 (18)
O5^xiv—Sr1—O2	119.77 (15)	Sr1^xxv—O2—Ba2^xxvii	99.0 (3)
O5^xv—Sr1—O2	63.23 (14)	Sr1—O2—Ba2^xxvii	169.7 (2)
O2^xiv—Sr1—O2	58.71 (16)	Nb2^xxv—O2—Ba2^xxi	85.31 (16)
O2^xv—Sr1—O2	58.71 (16)	Nb2^xxvi—O2—Ba2^xxi	90.82 (16)
O2^x—Sr1—O2^xiii	120.64 (5)	Sr1^xxv—O2—Ba2^xxi	170.8 (3)
O2^xi—Sr1—O2^xiii	120.63 (5)	Sr1—O2—Ba2^xxi	97.8 (2)
O2^xii—Sr1—O2^xiii	91.11 (8)	Ba2^xxvii—O2—Ba2^xxi	72.04 (6)
O2^iii—Sr1—O2^xiii	178.9 (3)	Nb2^xxviii—O3—Nb1^xxix	142.53 (16)
O5^xiii—Sr1—O2^xiii	61.12 (15)	Nb2^xxviii—O3—Ba2^ii	115.56 (12)
O5—Sr1—O2^xiii	121.94 (16)	Nb1^xxix—O3—Ba2^ii	100.94 (11)
O5^xiv—Sr1—O2^xiii	63.23 (14)	Nb2^xxviii—O3—Sr2^ii	115.56 (12)
O5^xv—Sr1—O2^xiii	119.77 (15)	Nb1^xxix—O3—Sr2^ii	100.94 (11)
O2^xiv—Sr1—O2^xiii	58.71 (16)	Nb2^xxviii—O3—Sr2^xxx	101.28 (11)
O2^xv—Sr1—O2^xiii	58.71 (16)	Nb1^xxix—O3—Sr2^xxx	88.96 (10)
O2—Sr1—O2^xiii	87.8 (3)	Ba2^ii—O3—Sr2^xxx	85.94 (8)
O4—Nb1—O3^xvi	98.22 (9)	Sr2^ii—O3—Sr2^xxx	85.94 (8)
O4—Nb1—O3^xvii	98.22 (9)	Nb2^xxviii—O3—Ba2^xxx	101.28 (11)
O3^xvi—Nb1—O3^xvii	163.56 (19)	Nb1^xxix—O3—Ba2^xxx	88.96 (10)
O4—Nb1—O3^xviii	98.22 (9)	Ba2^ii—O3—Ba2^xxx	85.94 (8)
O3^xvi—Nb1—O3^xviii	84.40 (16)	Sr2^ii—O3—Ba2^xxx	85.94 (8)
O3^xvii—Nb1—O3^xviii	93.25 (17)	Nb1—O4—Nb1^xxv	180.0
O4—Nb1—O3^viii	98.22 (9)	Nb1—O4—Ba2^xxi	92.80 (17)
O3^xvi—Nb1—O3^viii	93.25 (17)	Nb1^xxv—O4—Ba2^xxi	87.20 (17)
O3^xvii—Nb1—O3^viii	84.40 (16)	Nb1—O4—Ba2^xxxi	92.80 (17)
O3^xviii—Nb1—O3^viii	163.56 (19)	Nb1^xxv—O4—Ba2^xxxi	87.20 (17)
O4—Nb1—O4^iii	180.000 (1)	Ba2^xxi—O4—Ba2^xxxi	174.4 (3)
O3^xvi—Nb1—O4^iii	81.78 (9)	Nb1—O4—Sr2^xxi	92.80 (17)
O3^xvii—Nb1—O4^iii	81.78 (9)	Nb1^xxv—O4—Sr2^xxi	87.20 (17)
O3^xviii—Nb1—O4^iii	81.78 (9)	Ba2^xxxi—O4—Sr2^xxi	174.4 (3)
O3^viii—Nb1—O4^iii	81.78 (9)	Nb1—O4—Sr2^xxxi	92.80 (17)
O4—Nb1—Sr2^xix	122.53 (3)	Nb1^xxv—O4—Sr2^xxxi	87.20 (17)
O3^xvi—Nb1—Sr2^xix	122.41 (9)	Ba2^xxi—O4—Sr2^xxxi	174.4 (3)
O3^xvii—Nb1—Sr2^xix	46.39 (8)	Sr2^xxi—O4—Sr2^xxxi	174.4 (3)
O3^xviii—Nb1—Sr2^xix	122.41 (9)	Nb2—O5—Nb2^xxv	174.9 (3)
O3^viii—Nb1—Sr2^xix	46.39 (8)	Nb2—O5—Sr1	93.66 (17)
O4^iii—Nb1—Sr2^xix	57.47 (3)	Nb2^xxv—O5—Sr1	89.84 (16)
O4—Nb1—Ba2^xx	122.53 (3)	Nb2—O5—Ba2^xxi	93.71 (19)
O3^xvi—Nb1—Ba2^xx	46.39 (8)	Nb2^xxv—O5—Ba2^xxi	89.11 (18)
O3^xvii—Nb1—Ba2^xx	122.41 (9)	Sr1—O5—Ba2^xxi	103.23 (15)
O3^xviii—Nb1—Ba2^xx	46.39 (8)	Nb2—O5—Sr2^xxi	93.71 (19)
O3^viii—Nb1—Ba2^xx	122.41 (9)	Nb2^xxv—O5—Sr2^xxi	89.11 (18)
O4^iii—Nb1—Ba2^xx	57.47 (3)	Sr1—O5—Sr2^xxi	103.23 (15)

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

 

Footnotes

¹Supplementary data for this paper are available from the IUCr electronic archives (Reference: WS5047 ). Services for accessing these data are described at the back of the journal.