Structural changes of relaxor ferroelectric Sr_0.52Ba_0.48Nb₂O₆ (SBN52) on quenching and reheating

Quenching of Sr_0.52Ba_0.48Nb₂O₆ (SBN52) from temperatures above 700°C causes small modifications in the strontium distribution over the large cation sites (Me1 and Me2), changed off-centre shifts of the Nb atoms and slightly increased modulation amplitudes. The higher disorder of cation incorporation can explain the enhanced ferroelectric properties. The quenched structural disorder can be healed by reheating followed by slow cooling. A change of the modulation dimension on quenching such as for Ca_xBa_1−xNb₂O₆ (CBN) mixed crystals was not observed.

Computing details

For both structures, data collection: CrysAlis PRO 1.171.38.43 (Rigaku OD, 2015); cell refinement: CrysAlis PRO 1.171.38.43 (Rigaku OD, 2015); data reduction: CrysAlis PRO 1.171.38.43 (Rigaku OD, 2015); program(s) used to solve structure: SHELXS, Jana2006; program(s) used to refine structure: SHELXL, Jana2006; molecular graphics: Vesta 3; software used to prepare material for publication: Jana2006.

(sbn52untreated-tet)

Crystal data

bariumstrontiumniobiumoxide	Dx = 5.314 Mg m^−3
Mr = 393.1	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, X4bm†	Cell parameters from 17512 reflections
q1 = 0.290700a* + 0.290700b*; q2 = -0.290700a* + 0.290700b*	θ = 2.8–31.0°
a = 12.4693 (3) Å	µ = 13.96 mm^−1
c = 7.9006 (3) Å	T = 293 K
V = 1228.41 (6) Å^3	, colourless
Z = 10	0.29 × 0.16 × 0.13 mm
F(000) = 1767

† Symmetry operations: (1) x₁, x₂, x₃, x₄, x₅; (2) −x₂, x₁, x₃, −x₅, x₄; (3) −x₁+1/2, x₂+1/2, x₃, x₅, x₄; (4) −x₁, −x₂, x₃, −x₄, −x₅; (5) −x₂+1/2, −x₁+1/2, x₃, −x₄, x₅; (6) x₂, −x₁, x₃, x₅, −x₄; (7) x₁+1/2, −x₂+1/2, x₃, −x₅, −x₄; (8) x₂+1/2, x₁+1/2, x₃, x₄, −x₅; (9) x₁, x₂, x₃+1/2, x₄+1/2, x₅+1/2; (10) −x₂, x₁, x₃+1/2, −x₅+1/2, x₄+1/2; (11) −x₁+1/2, x₂+1/2, x₃+1/2, x₅+1/2, x₄+1/2; (12) −x₁, −x₂, x₃+1/2, −x₄+1/2, −x₅+1/2; (13) −x₂+1/2, −x₁+1/2, x₃+1/2, −x₄+1/2, x₅+1/2; (14) x₂, −x₁, x₃+1/2, x₅+1/2, −x₄+1/2; (15) x₁+1/2, −x₂+1/2, x₃+1/2, −x₅+1/2, −x₄+1/2; (16) x₂+1/2, x₁+1/2, x₃+1/2, x₄+1/2, −x₅+1/2.

Data collection

Xcalibur, Sapphire2, large Be window diffractometer	4873 independent reflections
Radiation source: X-ray tube	2033 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 8.2495 pixels mm^-1	θmax = 30.6°, θmin = 2.9°
ω and φ scans	h = −17→18
Absorption correction: analytical CrysAlisPro 1.171.38.43 (Rigaku Oxford Diffraction, 2015) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −18→18
Tmin = 0.073, Tmax = 0.265	l = −11→11
42683 measured reflections

Refinement

Refinement on F	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
R[F^2 > 2σ(F^2)] = 0.027	(Δ/σ)max = 0.008
wR(F^2) = 0.042	Δρmax = 0.91 e Å^−3
S = 1.18	Δρmin = −1.11 e Å^−3
4873 reflections	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
158 parameters	Extinction coefficient: 1000 (30)
0 restraints	Absolute structure: 2365 of Friedel pairs used in the refinement
1 constraint	Absolute structure parameter: 0.587 (10)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ba2	0.171985 (15)	0.671985 (15)	0.25	0.02427 (8)	0.5977
Sr1	0	0	0.24659 (8)	0.00787 (12)	0.7162
Nb1	0	0.5	0.00997 (6)	0.00946 (9)
Nb2	0.074328 (16)	0.211501 (16)	0.00278 (5)	0.01081 (6)
O1	0.21748 (15)	0.28252 (15)	−0.0141 (5)	0.0128 (6)
O2	0.13920 (16)	0.06966 (15)	−0.0156 (4)	0.0221 (7)
O3	−0.00652 (16)	0.34319 (15)	−0.0167 (4)	0.0177 (6)
O4	0	0.5	0.2459 (8)	0.0324 (11)
O5	0.0761 (2)	0.20431 (18)	0.2342 (3)	0.0254 (8)
Sr2	0.171985 (15)	0.671985 (15)	0.25	0.02427 (8)	0.296

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba2	0.0290 (1)	0.0290 (1)	0.0149 (1)	−0.0168 (1)	−0.0005 (2)	−0.0005 (2)
Sr1	0.00821 (17)	0.00821 (17)	0.0072 (3)	0	0	0
Nb1	0.00966 (13)	0.00966 (13)	0.00908 (19)	−0.00140 (13)	0	0
Nb2	0.01040 (11)	0.01024 (11)	0.01180 (11)	0.00143 (7)	−0.00091 (16)	−0.00081 (19)
O1	0.0116 (7)	0.0116 (7)	0.0150 (15)	−0.0042 (9)	−0.0065 (10)	0.0065 (10)
O2	0.0173 (10)	0.0089 (9)	0.0402 (15)	0.0054 (7)	−0.0058 (14)	−0.0082 (13)
O3	0.0193 (10)	0.0071 (8)	0.0267 (13)	0.0029 (6)	−0.0009 (12)	−0.0040 (11)
O4	0.0408 (17)	0.0408 (17)	0.016 (2)	0.001 (2)	0	0
O5	0.0532 (16)	0.0226 (11)	0.0003 (13)	−0.0137 (10)	0.0023 (12)	0.0001 (10)
Sr2	0.0290 (1)	0.0290 (1)	0.0149 (1)	−0.0168 (1)	−0.0005 (2)	−0.0005 (2)

Bond lengths (Å)

	Average	Minimum	Maximum
Ba2—Ba2^i	3.9458 (15)	3.9322 (15)	3.9723 (15)
Ba2—Ba2^ii	3.9591 (15)	3.9322 (15)	3.9723 (15)
Ba2—Sr1^iii	4.5997 (13)	4.5623 (13)	4.6744 (13)
Ba2—Sr1^iv	4.6387 (9)	4.5528 (9)	4.6838 (9)
Ba2—Nb1	3.5795 (12)	3.5497 (12)	3.6052 (12)
Ba2—Nb1^ii	3.6635 (12)	3.6477 (12)	3.6794 (12)
Ba2—Nb2^iv	3.7614 (14)	3.6866 (14)	3.8144 (14)
Ba2—Nb2^v	3.7828 (14)	3.7349 (14)	3.8123 (14)
Ba2—Nb2^vi	3.9001 (14)	3.8553 (14)	3.9834 (14)
Ba2—Nb2^vii	3.9281 (14)	3.8916 (14)	3.9908 (14)
Ba2—Nb2^viii	3.9390 (14)	3.8609 (14)	3.9781 (14)
Ba2—Nb2^ix	3.9545 (14)	3.9017 (14)	3.9806 (14)
Ba2—Nb2^x	3.7368 (14)	3.7089 (14)	3.7921 (14)
Ba2—Nb2^xi	3.7652 (14)	3.7478 (14)	3.7997 (14)
Ba2—O1^iv	2.844 (8)	2.819 (8)	2.893 (8)
Ba2—O1^v	2.697 (8)	2.662 (8)	2.735 (8)
Ba2—O2^iv	3.416 (9)	3.370 (9)	3.438 (9)
Ba2—O2^v	3.259 (9)	3.217 (10)	3.300 (10)
Ba2—O2^x	3.406 (9)	3.376 (10)	3.431 (10)
Ba2—O2^xi	3.266 (10)	3.234 (10)	3.283 (10)
Ba2—O3^vi	2.951 (8)	2.859 (9)	3.061 (9)
Ba2—O3^vii	2.772 (9)	2.716 (9)	2.843 (9)
Ba2—O3^viii	2.922 (9)	2.852 (9)	3.068 (9)
Ba2—O3^ix	2.749 (9)	2.698 (9)	2.858 (9)
Ba2—O4	3.074 (5)	2.890 (5)	3.178 (5)
Ba2—O5^iv	3.206 (7)	2.926 (7)	3.415 (7)
Ba2—O5^vi	3.409 (6)	3.216 (7)	3.702 (7)
Ba2—O5^viii	3.541 (7)	3.215 (7)	3.704 (7)
Ba2—O5^x	3.132 (7)	3.056 (7)	3.285 (7)
Ba2—Sr2	0	0	0
Ba2—Sr2^i	3.9458 (15)	3.9322 (15)	3.9723 (15)
Ba2—Sr2^ii	3.9591 (15)	3.9322 (15)	3.9723 (15)
Sr1—Sr1^i	3.951 (3)	3.947 (3)	3.954 (3)
Sr1—Sr1^ii	3.949 (3)	3.947 (3)	3.954 (3)
Sr1—Nb2	3.3947 (17)	3.3874 (17)	3.4024 (17)
Sr1—Nb2^ii	3.4501 (17)	3.4476 (17)	3.4548 (17)
Sr1—Nb2^xii	3.3947 (17)	3.3874 (17)	3.4024 (17)
Sr1—Nb2^xiii	3.4501 (17)	3.4476 (17)	3.4548 (17)
Sr1—Nb2^xiv	3.3947 (17)	3.3874 (17)	3.4024 (17)
Sr1—Nb2^xv	3.4501 (17)	3.4476 (17)	3.4548 (17)
Sr1—Nb2^xvi	3.3947 (17)	3.3874 (17)	3.4024 (17)
Sr1—Nb2^xvii	3.4501 (17)	3.4476 (17)	3.4548 (17)
Sr1—O2	2.840 (9)	2.678 (9)	3.003 (9)
Sr1—O2^ii	2.707 (9)	2.614 (9)	2.798 (9)
Sr1—O2^xii	2.840 (9)	2.678 (9)	3.003 (9)
Sr1—O2^xiii	2.707 (9)	2.614 (9)	2.798 (9)
Sr1—O2^xiv	2.840 (9)	2.678 (9)	3.003 (9)
Sr1—O2^xv	2.707 (9)	2.614 (9)	2.798 (9)
Sr1—O2^xvi	2.840 (9)	2.678 (9)	3.003 (9)
Sr1—O2^xvii	2.707 (9)	2.614 (9)	2.798 (9)
Sr1—O5	2.726 (6)	2.718 (6)	2.742 (6)
Sr1—O5^xii	2.726 (6)	2.718 (6)	2.742 (6)
Sr1—O5^xiv	2.726 (6)	2.718 (6)	2.742 (6)
Sr1—O5^xvi	2.726 (6)	2.718 (6)	2.742 (6)
Sr1—Sr2^xviii	4.6391 (7)	4.5540 (7)	4.6827 (7)
Sr1—Sr2^xix	4.6391 (7)	4.5540 (7)	4.6827 (7)
Sr1—Sr2^vi	4.6391 (7)	4.5540 (7)	4.6827 (7)
Sr1—Sr2^xx	4.6391 (7)	4.5540 (7)	4.6827 (7)
Nb1—O3	1.974 (10)	1.965 (10)	1.990 (10)
Nb1—O3^vi	1.969 (10)	1.959 (10)	1.978 (10)
Nb1—O3^viii	1.974 (10)	1.956 (10)	1.981 (10)
Nb1—O3^xxi	1.970 (10)	1.967 (10)	1.987 (10)
Nb1—O4	1.879 (10)	1.852 (10)	1.892 (10)
Nb1—O4^i	2.101 (10)	2.079 (10)	2.112 (10)
Nb1—Sr2	3.5795 (12)	3.5497 (12)	3.6052 (12)
Nb1—Sr2^i	3.6636 (12)	3.6477 (12)	3.6794 (12)
Nb1—Sr2^vi	3.5735 (12)	3.5658 (12)	3.5889 (12)
Nb1—Sr2^xxii	3.6641 (12)	3.6493 (12)	3.6779 (12)
Nb2—O1	1.996 (9)	1.981 (9)	2.021 (9)
Nb2—O2	1.959 (10)	1.935 (10)	1.966 (10)
Nb2—O2^xii	2.014 (10)	2.002 (10)	2.035 (10)
Nb2—O3	1.933 (10)	1.920 (10)	1.946 (10)
Nb2—O5	1.846 (9)	1.806 (9)	1.863 (9)
Nb2—O5^i	2.144 (9)	2.094 (9)	2.159 (9)
Nb2—Sr2^xix	3.7631 (14)	3.6917 (14)	3.8095 (14)
Nb2—Sr2^xxiii	3.7624 (14)	3.7400 (14)	3.8073 (14)
Nb2—Sr2^vi	3.9368 (14)	3.8611 (14)	3.9781 (14)
Nb2—Sr2^xxii	3.9277 (14)	3.9004 (14)	3.9824 (14)
O1—Sr2^xix	2.871 (8)	2.755 (8)	2.958 (8)
O1—Sr2^xxiii	2.702 (8)	2.671 (8)	2.728 (8)
O3—Sr2^vi	2.968 (9)	2.832 (9)	3.088 (9)
O3—Sr2^xxii	2.774 (9)	2.691 (9)	2.865 (9)
O4—Sr2	3.074 (5)	2.890 (5)	3.178 (5)
O4—Sr2^vi	2.992 (5)	2.908 (5)	3.160 (5)
O5—Sr2^xix	3.181 (7)	2.852 (7)	3.489 (7)
Sr2—Sr2^i	3.9458 (15)	3.9322 (15)	3.9723 (15)
Sr2—Sr2^ii	3.9591 (15)	3.9322 (15)	3.9723 (15)

Symmetry codes: (i) x₁, x₂, x₃−1/2, x₄+1/2, x₅+1/2; (ii) x₁, x₂, x₃+1/2, x₄+1/2, x₅+1/2; (iii) x₁, x₂+1, x₃, x₄, x₅; (iv) −x₁+1/2, x₂+1/2, x₃, x₅, x₄; (v) −x₁+1/2, x₂+1/2, x₃+1/2, x₅+1/2, x₄+1/2; (vi) −x₁, −x₂+1, x₃, −x₄, −x₅; (vii) −x₁, −x₂+1, x₃+1/2, −x₄+1/2, −x₅+1/2; (viii) −x₂+1/2, −x₁+1/2, x₃, −x₄, x₅; (ix) −x₂+1/2, −x₁+1/2, x₃+1/2, −x₄+1/2, x₅+1/2; (x) x₂, −x₁+1, x₃, x₅, −x₄; (xi) x₂, −x₁+1, x₃+1/2, x₅+1/2, −x₄+1/2; (xii) −x₂, x₁, x₃, −x₅, x₄; (xiii) −x₂, x₁, x₃+1/2, −x₅+1/2, x₄+1/2; (xiv) −x₁, −x₂, x₃, −x₄, −x₅; (xv) −x₁, −x₂, x₃+1/2, −x₄+1/2, −x₅+1/2; (xvi) x₂, −x₁, x₃, x₅, −x₄; (xvii) x₂, −x₁, x₃+1/2, x₅+1/2, −x₄+1/2; (xviii) x₁, x₂−1, x₃, x₄, x₅; (xix) −x₂+1, x₁, x₃, −x₅, x₄; (xx) x₂−1, −x₁, x₃, x₅, −x₄; (xxi) x₂−1/2, x₁+1/2, x₃, x₄, −x₅; (xxii) −x₁, −x₂+1, x₃−1/2, −x₄+1/2, −x₅+1/2; (xxiii) −x₂+1, x₁, x₃−1/2, −x₅+1/2, x₄+1/2.

(sbn52quenchedfrom1200-tet)

Crystal data

bariumstrontiumniobiumoxide	Dx = 5.313 Mg m^−3
Mr = 392.8	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, X4bm†	Cell parameters from 13535 reflections
q1 = 0.293525a* + 0.293525b*; q2 = -0.293525a* + 0.293525b*	θ = 3.0–42.4°
a = 12.4629 (3) Å	µ = 14 mm^−1
c = 7.9032 (3) Å	T = 293 K
V = 1227.56 (6) Å^3	, colourless
Z = 10	0.25 × 0.16 × 0.06 mm
F(000) = 1767

† Symmetry operations: (1) x₁, x₂, x₃, x₄, x₅; (2) −x₂, x₁, x₃, −x₅, x₄; (3) −x₁+1/2, x₂+1/2, x₃, x₅, x₄; (4) −x₁, −x₂, x₃, −x₄, −x₅; (5) −x₂+1/2, −x₁+1/2, x₃, −x₄, x₅; (6) x₂, −x₁, x₃, x₅, −x₄; (7) x₁+1/2, −x₂+1/2, x₃, −x₅, −x₄; (8) x₂+1/2, x₁+1/2, x₃, x₄, −x₅; (9) x₁, x₂, x₃+1/2, x₄+1/2, x₅+1/2; (10) −x₂, x₁, x₃+1/2, −x₅+1/2, x₄+1/2; (11) −x₁+1/2, x₂+1/2, x₃+1/2, x₅+1/2, x₄+1/2; (12) −x₁, −x₂, x₃+1/2, −x₄+1/2, −x₅+1/2; (13) −x₂+1/2, −x₁+1/2, x₃+1/2, −x₄+1/2, x₅+1/2; (14) x₂, −x₁, x₃+1/2, x₅+1/2, −x₄+1/2; (15) x₁+1/2, −x₂+1/2, x₃+1/2, −x₅+1/2, −x₄+1/2; (16) x₂+1/2, x₁+1/2, x₃+1/2, x₄+1/2, −x₅+1/2.

Data collection

Xcalibur, Sapphire2, large Be window diffractometer	7638 independent reflections
Radiation source: X-ray tube	2775 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.028
Detector resolution: 8.2495 pixels mm^-1	θmax = 36.4°, θmin = 2.9°
ω and π scans	h = −18→20
Absorption correction: analytical CrysAlisPro, Agilent Technologies, Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET) (compiled Aug 13 2014,18:06:01) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −20→20
Tmin = 0.198, Tmax = 0.547	l = −13→13
52674 measured reflections

Refinement

Refinement on F	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
R[F^2 > 2σ(F^2)] = 0.029	(Δ/σ)max = 0.022
wR(F^2) = 0.046	Δρmax = 1.18 e Å^−3
S = 1.11	Δρmin = −1.14 e Å^−3
7638 reflections	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
190 parameters	Extinction coefficient: 169 (16)
0 restraints	Absolute structure: 3726 of Friedel pairs used in the refinement
1 constraint	Absolute structure parameter: 0.468 (10)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ba2	0.171927 (13)	0.671927 (13)	0.249999	0.02429 (6)	0.598
Sr1	0	0	0.24703 (8)	0.00778 (9)	0.6808
Nb1	0	0.5	0.00944 (5)	0.00829 (6)
Nb2	0.074330 (13)	0.211081 (13)	0.00306 (5)	0.00976 (5)
O1	0.21804 (13)	0.28196 (13)	−0.0143 (4)	0.0111 (5)
O2	0.13972 (14)	0.06969 (13)	−0.0180 (4)	0.0215 (6)
O3	−0.00699 (14)	0.34350 (13)	−0.0174 (3)	0.0172 (5)
O4	0	0.5	0.2451 (7)	0.0335 (10)
O5	0.07602 (17)	0.20470 (15)	0.2347 (2)	0.0250 (6)
Sr2	0.171927 (13)	0.671927 (13)	0.249999	0.02429 (6)	0.3137

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba2	0.0292 (1)	0.0292 (1)	0.0144 (1)	−0.0174 (1)	−0.0001 (1)	−0.0001 (1)
Sr1	0.00753 (13)	0.00753 (13)	0.0083 (2)	0	0	0
Nb1	0.00829 (9)	0.00829 (9)	0.00830 (13)	−0.00075 (10)	0	0
Nb2	0.00950 (8)	0.00884 (8)	0.01096 (8)	0.00144 (6)	−0.00031 (14)	−0.00107 (15)
O1	0.0105 (5)	0.0105 (5)	0.0124 (12)	−0.0035 (7)	−0.0061 (8)	0.0061 (8)
O2	0.0179 (8)	0.0077 (7)	0.0390 (14)	0.0057 (6)	−0.0073 (11)	−0.0067 (10)
O3	0.0171 (8)	0.0071 (7)	0.0275 (11)	0.0030 (5)	0.0001 (10)	−0.0071 (9)
O4	0.0433 (16)	0.0433 (16)	0.0138 (19)	0.0022 (19)	0	0
O5	0.0535 (14)	0.0206 (9)	0.0010 (10)	−0.0141 (9)	0.0030 (9)	−0.0008 (7)
Sr2	0.0292 (1)	0.0292 (1)	0.0144 (1)	−0.0174 (1)	−0.0001 (1)	−0.0001 (1)

Bond lengths (Å)

	Average	Minimum	Maximum
Ba2—Ba2^i	3.9481 (12)	3.9360 (12)	3.9717 (12)
Ba2—Ba2^ii	3.9600 (12)	3.9360 (12)	3.9717 (12)
Ba2—Sr1^iii	4.5958 (12)	4.5546 (12)	4.6779 (12)
Ba2—Sr1^iv	4.6377 (8)	4.5456 (8)	4.6869 (8)
Ba2—Nb1	3.5810 (10)	3.5459 (10)	3.6096 (10)
Ba2—Nb1^ii	3.6597 (10)	3.6429 (10)	3.6764 (10)
Ba2—Nb2^iv	3.7606 (11)	3.6787 (11)	3.8178 (11)
Ba2—Nb2^v	3.7829 (11)	3.7305 (11)	3.8170 (11)
Ba2—Nb2^vi	3.8985 (11)	3.8486 (11)	3.9888 (11)
Ba2—Nb2^vii	3.9286 (11)	3.8909 (11)	3.9949 (11)
Ba2—Nb2^viii	3.9404 (11)	3.8542 (11)	3.9835 (11)
Ba2—Nb2^ix	3.9566 (11)	3.9020 (11)	3.9836 (11)
Ba2—Nb2^x	3.7335 (11)	3.7035 (11)	3.7931 (11)
Ba2—Nb2^xi	3.7641 (11)	3.7441 (11)	3.8038 (11)
Ba2—O1^iv	2.839 (6)	2.815 (6)	2.887 (6)
Ba2—O1^v	2.689 (6)	2.655 (6)	2.727 (6)
Ba2—O2^iv	3.418 (8)	3.391 (8)	3.430 (8)
Ba2—O2^v	3.244 (8)	3.204 (8)	3.282 (8)
Ba2—O2^x	3.414 (8)	3.388 (8)	3.433 (8)
Ba2—O2^xi	3.253 (8)	3.207 (8)	3.278 (8)
Ba2—O3^vi	2.952 (7)	2.844 (7)	3.077 (7)
Ba2—O3^vii	2.763 (7)	2.696 (7)	2.849 (7)
Ba2—O3^viii	2.916 (7)	2.834 (7)	3.086 (7)
Ba2—O3^ix	2.738 (7)	2.679 (7)	2.863 (7)
Ba2—O4	3.081 (5)	2.858 (5)	3.206 (5)
Ba2—O5^iv	3.210 (6)	2.888 (6)	3.452 (6)
Ba2—O5^vi	3.398 (6)	3.173 (6)	3.735 (6)
Ba2—O5^viii	3.546 (6)	3.179 (6)	3.730 (6)
Ba2—O5^x	3.126 (6)	3.036 (6)	3.305 (6)
Ba2—Sr2	0	0	0
Ba2—Sr2^i	3.9481 (12)	3.9360 (12)	3.9717 (12)
Ba2—Sr2^ii	3.9600 (12)	3.9360 (12)	3.9717 (12)
Sr1—Sr1^i	3.955 (3)	3.940 (3)	3.963 (3)
Sr1—Sr1^ii	3.948 (3)	3.940 (3)	3.963 (3)
Sr1—Nb2	3.3913 (14)	3.3838 (14)	3.3977 (14)
Sr1—Nb2^ii	3.4445 (14)	3.4418 (14)	3.4497 (14)
Sr1—Nb2^xii	3.3913 (14)	3.3838 (14)	3.3977 (14)
Sr1—Nb2^xiii	3.4445 (14)	3.4418 (14)	3.4497 (14)
Sr1—Nb2^xiv	3.3913 (14)	3.3838 (14)	3.3977 (14)
Sr1—Nb2^xv	3.4445 (14)	3.4418 (14)	3.4497 (14)
Sr1—Nb2^xvi	3.3913 (14)	3.3838 (14)	3.3977 (14)
Sr1—Nb2^xvii	3.4445 (14)	3.4418 (14)	3.4497 (14)
Sr1—O2	2.863 (7)	2.684 (7)	3.039 (7)
Sr1—O2^ii	2.691 (7)	2.585 (7)	2.806 (7)
Sr1—O2^xii	2.863 (7)	2.684 (7)	3.039 (7)
Sr1—O2^xiii	2.691 (7)	2.585 (7)	2.806 (7)
Sr1—O2^xiv	2.863 (7)	2.684 (7)	3.039 (7)
Sr1—O2^xv	2.691 (7)	2.585 (7)	2.806 (7)
Sr1—O2^xvi	2.863 (7)	2.684 (7)	3.039 (7)
Sr1—O2^xvii	2.691 (7)	2.585 (7)	2.806 (7)
Sr1—O5	2.731 (5)	2.722 (5)	2.752 (5)
Sr1—O5^xii	2.731 (5)	2.722 (5)	2.752 (5)
Sr1—O5^xiv	2.731 (5)	2.722 (5)	2.752 (5)
Sr1—O5^xvi	2.731 (5)	2.722 (5)	2.752 (5)
Sr1—Sr2^xviii	4.6384 (6)	4.5477 (6)	4.6848 (6)
Sr1—Sr2^xix	4.6384 (6)	4.5477 (6)	4.6848 (6)
Sr1—Sr2^vi	4.6384 (6)	4.5477 (6)	4.6848 (6)
Sr1—Sr2^xx	4.6384 (6)	4.5477 (6)	4.6848 (6)
Nb1—O3	1.970 (8)	1.960 (8)	1.977 (8)
Nb1—O3^vi	1.967 (8)	1.958 (8)	1.988 (8)
Nb1—O3^viii	1.967 (8)	1.954 (8)	1.983 (8)
Nb1—O3^xxi	1.972 (8)	1.963 (8)	1.982 (8)
Nb1—O4	1.875 (8)	1.854 (8)	1.892 (8)
Nb1—O4^i	2.103 (8)	2.077 (8)	2.126 (8)
Nb1—Sr2	3.5810 (10)	3.5459 (10)	3.6096 (10)
Nb1—Sr2^i	3.6597 (10)	3.6429 (10)	3.6764 (10)
Nb1—Sr2^vi	3.5741 (10)	3.5663 (10)	3.5890 (10)
Nb1—Sr2^xxii	3.6609 (10)	3.6466 (10)	3.6730 (10)
Nb2—O1	2.002 (7)	1.986 (7)	2.027 (7)
Nb2—O2	1.957 (8)	1.938 (8)	1.968 (8)
Nb2—O2^xii	2.011 (8)	2.000 (8)	2.032 (8)
Nb2—O3	1.945 (8)	1.934 (8)	1.967 (8)
Nb2—O5	1.846 (7)	1.821 (7)	1.866 (7)
Nb2—O5^i	2.140 (7)	2.108 (7)	2.161 (7)
Nb2—Sr2^xix	3.7628 (11)	3.6855 (11)	3.8114 (11)
Nb2—Sr2^xxiii	3.7622 (11)	3.7382 (11)	3.8093 (11)
Nb2—Sr2^vi	3.9383 (11)	3.8579 (11)	3.9802 (11)
Nb2—Sr2^xxii	3.9288 (11)	3.9004 (11)	3.9858 (11)
O1—Sr2^xix	2.865 (6)	2.748 (6)	2.956 (6)
O1—Sr2^xxiii	2.694 (6)	2.657 (6)	2.727 (6)
O3—Sr2^vi	2.968 (7)	2.808 (7)	3.111 (7)
O3—Sr2^xxii	2.767 (7)	2.677 (7)	2.865 (7)
O4—Sr2	3.081 (5)	2.858 (5)	3.206 (5)
O4—Sr2^vi	2.981 (5)	2.878 (5)	3.186 (5)
O5—Sr2^xix	3.185 (6)	2.811 (6)	3.530 (6)
O5—Sr2^vi	3.476 (6)	3.082 (6)	3.826 (6)
Sr2—Sr2^i	3.9481 (12)	3.9360 (12)	3.9717 (12)
Sr2—Sr2^ii	3.9600 (12)	3.9360 (12)	3.9717 (12)

Symmetry codes: (i) x₁, x₂, x₃−1/2, x₄+1/2, x₅+1/2; (ii) x₁, x₂, x₃+1/2, x₄+1/2, x₅+1/2; (iii) x₁, x₂+1, x₃, x₄, x₅; (iv) −x₁+1/2, x₂+1/2, x₃, x₅, x₄; (v) −x₁+1/2, x₂+1/2, x₃+1/2, x₅+1/2, x₄+1/2; (vi) −x₁, −x₂+1, x₃, −x₄, −x₅; (vii) −x₁, −x₂+1, x₃+1/2, −x₄+1/2, −x₅+1/2; (viii) −x₂+1/2, −x₁+1/2, x₃, −x₄, x₅; (ix) −x₂+1/2, −x₁+1/2, x₃+1/2, −x₄+1/2, x₅+1/2; (x) x₂, −x₁+1, x₃, x₅, −x₄; (xi) x₂, −x₁+1, x₃+1/2, x₅+1/2, −x₄+1/2; (xii) −x₂, x₁, x₃, −x₅, x₄; (xiii) −x₂, x₁, x₃+1/2, −x₅+1/2, x₄+1/2; (xiv) −x₁, −x₂, x₃, −x₄, −x₅; (xv) −x₁, −x₂, x₃+1/2, −x₄+1/2, −x₅+1/2; (xvi) x₂, −x₁, x₃, x₅, −x₄; (xvii) x₂, −x₁, x₃+1/2, x₅+1/2, −x₄+1/2; (xviii) x₁, x₂−1, x₃, x₄, x₅; (xix) −x₂+1, x₁, x₃, −x₅, x₄; (xx) x₂−1, −x₁, x₃, x₅, −x₄; (xxi) x₂−1/2, x₁+1/2, x₃, x₄, −x₅; (xxii) −x₁, −x₂+1, x₃−1/2, −x₄+1/2, −x₅+1/2; (xxiii) −x₂+1, x₁, x₃−1/2, −x₅+1/2, x₄+1/2.