Sr9La2(WO6)4 containing [WO6] octa­hedra

Simura, R.; Watanabe, T.; Yamane, H.

doi:10.1107/S2056989022006648

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 78| Part 8| August 2022| Pages 766-769

https://doi.org/10.1107/S2056989022006648

Open

access

Sr₉La₂(WO₆)₄ containing [WO₆] octahedra

Rayko Simura,^a ^* Tomoki Watanabe ^a and Hisanori Yamane ^a

^aInstitute of Multidisciplinary Research for Advanced Materials, Tohoku, University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
^*Correspondence e-mail: ray@tohoku.ac.jp

Edited by M. Weil, Vienna University of Technology, Austria (Received 28 May 2022; accepted 28 June 2022; online 5 July 2022)

A polycrystalline sample of Sr₉La₂(WO₆)₄, nonastrontium dilanthanum tetrakis[orthotungstate(VI)], was prepared by heating a compacted powder mixture of SrCO₃, WO₃, and La₂O₃ with an Sr:La:W molar ratio of 9:2:4 at 1473 K. X-ray crystal structure analysis was performed for a Sr₉La₂(WO₆)₄ single-crystal grain grown by reheating the sample at 1673 K. Sr₉La₂(WO₆)₄ crystallizes with four formula units in the tetragonal space group I4₁/a and is isotypic with Sr₁₁(ReO₆)₄. Two W sites with site symmetries of $[\overline{1}]$ are located at the center of isolated [WO₆] octahedra, and four mixed (Sr/La) sites are surrounded by eight to twelve O atoms of the [WO₆] octahedra. The structure of Sr₉La₂(WO₆)₄ can be described on the basis of the double-perovskite structure with [WO₆] and [(Sr/La)O_x] polyhedra alternately placed, and a vacancy (□).

Keywords: crystal structure; tungstate; double perovskite.

CCDC reference: 2182445

1. Chemical context

The alkaline-earth (A) rare-earth (Ln) tungstates A₉Ln₂(WO₆)₄ have attracted attention as host crystals of phosphors, and various luminescence properties of these tungstates doped with activators such as Eu³⁺ and Mn⁴⁺ have been evaluated. For example, emissions of Eu³⁺ at ∼615 nm excited by ∼395 nm wavelength light have been reported for Sr₉Gd_1.5Eu_0.5(WO₆)₄ (Blasse & Kemmler-Sack, 1983 ), Ca₉Gd_2–xEu_x(WO₆)₄ (Zeng et al., 2013 ), Ca₉Eu₂(WO₆)₄ (Qin et al., 2012 ; Zeng et al., 2010 ), Sr₉Eu₂(WO₆)₄ (Qin et al., 2012; Blasse & Kemmler-Sack, 1983; Zeng et al., 2010), and Ca_9–xSr_xEu₂(WO₆)₄ (Zeng et al., 2009 ). Mn⁴⁺-doped Sr₉Y₂(WO₆)₄ (Shi et al., 2019 ) and Mn⁴⁺/Mg²⁺-doped Sr₉Y₂(WO₆)₄ (Zhou et al., 2020 ) were also studied, and deep-red luminescence with broad emission maxima at ∼680 nm were observed under excitation by light with a wavelength of 365 nm.

Unit-cell parameters of a tetragonal cell with a = 11.664 (2) Å, c = 16.335 (4) Å (Smirnov et al., 1987 ) and a = 16.44 (7) Å, c = 16.32 (3) Å (Kemmler-Sack & Ehmann, 1981 ) have been reported for Sr₉La₂(WO₆)₄. However, details of the crystal structure, including atom positions, have not been clarified up to now. Sr₉Ln₂(WO₆)₄ compounds prepared by substituting Ln (a rare-earth element) for La in Sr₉La₂(WO₆)₄ have also been reported. These materials have tetragonal symmetry for Ln = La, Pr, and Nd; cubic (high-temperature phase) and tetragonal (low-temperature phase) symmetry for Sm, Eu, and Gd; monoclinic symmetry for Tb and Dy; and cubic symmetry for Ho, Er, Tm, and Y (Kemmler-Sack & Ehmann, 1981). The Sr atoms of Sr₉La₂(WO₆)₄ can also be replaced with Ca or Ba. For Ca₉Ln₂(WO₆)₄ (Ln = Nd, Sm, Eu, Gd, Tb, Dy), lattice parameters of a tetragonal unit-cell with 11.05 ≤ a ≤ 11.13 Å and 16.37 ≤ c ≤ 16.42 Å and space group I4₁/a have been reported (Smirnov et al., 1987). Ba₉Ln₂(WO₆)₄ compounds (Ln = La, Nd, Sm, Eu) are cubic (8.50 ≤ a ≤ 8.56 Å; Betz et al., 1982 ). The crystal structures of Sr₉Gd₂(WO₆)₄ [Fm $[\overline{3}]$ , a = 16.47013 (6) Å] and Ba₉La₂(WO₆)₄ [Fm $[\overline{3}]$ , a = 17.12339 (15) Å] have been fully analyzed (Ijdo et al., 2016 ). However, atomic positions for the tetragonal structures of Ca₉Ln₂(WO₆)₄ (Ln = Nd, Sm, Eu, Gd, Tb, Dy) compounds have not been determined.

Here, we report on synthesis and crystal structure analysis of Sr₉La₂(WO₆)₄.

2. Structural commentary

The unit-cell parameters of Sr₉La₂(WO₆)₄ determined in the present investigation are consistent with those reported in previous studies (Smirnov et al., 1987; Kemmler-Sack & Ehmann, 1981). Fig. 1 displays the principal building units in the crystal structure of Sr₉La₂(WO₆)₄. W1 (multiplicity and Wyckoff letter 8d with site symmetry $[\overline{1}]$ ) and W2 (8c, $[\overline{1}]$ ) each are located at the center of a [WO₆] octahedron. The [WO₆] octahedra are isolated and surrounded by mixed-occupied (Sr,La) atoms. As detailed in Table 1, the interatomic distances between W and O are 1.901 (4)–1.934 (4) Å (average: 1.922 Å) for W1—O and 1.891 (4)–1.967 (4) Å (average: 1.925 Å) for W2—O. The bond-valence sums (BVS; Brown & Altermatt, 1985 ) for W1 and W2, as calculated using the parameters for W—O (R₀ = 1.921, B = 0.37) (Brese & O'Keeffe, 1991 ), are 5.994 and 5.957 valence units, respectively. These values are consistent with the valence state +VI for W.

Table 1
Selected bond lengths (Å)

Sr1/La1—O6ⁱ	2.333 (4)	Sr3/La3—O1^x	3.220 (4)
Sr1/La1—O2	2.438 (4)	Sr4/La4—O1	2.607 (4)
Sr1/La1—O2ⁱⁱ	2.453 (4)	Sr4/La4—O1^vi	2.607 (4)
Sr1/La1—O4ⁱⁱⁱ	2.458 (4)	Sr4/La4—O1^xi	2.607 (4)
Sr1/La1—O5^iv	2.728 (4)	Sr4/La4—O1^ix	2.607 (4)
Sr1/La1—O3ⁱⁱⁱ	2.765 (5)	Sr4/La4—O4	2.998 (5)
Sr1/La1—O3	2.849 (5)	Sr4/La4—O4^xi	2.998 (5)
Sr1/La1—O1ⁱⁱⁱ	2.861 (4)	Sr4/La4—O4^ix	2.998 (5)
Sr2/La2—O3^v	2.470 (4)	Sr4/La4—O4^vi	2.998 (5)
Sr2/La2—O1^vi	2.548 (4)	Sr4/La4—O5ⁱ	3.131 (4)
Sr2/La2—O6	2.599 (4)	Sr4/La4—O5^xii	3.131 (4)
Sr2/La2—O2^vii	2.603 (4)	Sr4/La4—O5^v	3.131 (4)
Sr2/La2—O1	2.642 (4)	Sr4/La4—O5^viii	3.131 (4)
Sr2/La2—O5	2.652 (4)	W1—O3	1.901 (4)
Sr2/La2—O5^v	2.704 (4)	W1—O3^xiii	1.901 (4)
Sr2/La2—O4	2.777 (4)	W1—O6^viii	1.930 (4)
Sr2/La2—O4^v	2.877 (5)	W1—O6^xiv	1.930 (4)
Sr3/La3—O6ⁱ	2.557 (4)	W1—O2	1.934 (4)
Sr3/La3—O6^viii	2.557 (4)	W1—O2^xiii	1.934 (4)
Sr3/La3—O5^viii	2.596 (4)	W2—O4^xi	1.891 (4)
Sr3/La3—O5ⁱ	2.596 (4)	W2—O4^v	1.891 (4)
Sr3/La3—O3	2.660 (4)	W2—O1^xv	1.917 (4)
Sr3/La3—O3^ix	2.660 (4)	W2—O1	1.917 (4)
Sr3/La3—O4^ix	2.773 (4)	W2—O5^xi	1.967 (4)
Sr3/La3—O4	2.773 (4)	W2—O5^v	1.967 (4)
Sr3/La3—O1ⁱⁱⁱ	3.220 (4)
Symmetry codes: (i) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-y+{\script{1\over 4}}, x+{\script{1\over 4}}, -z+{\script{5\over 4}}]$ ; (iii) $[y+{\script{1\over 4}}, -x+{\script{1\over 4}}, z+{\script{1\over 4}}]$ ; (iv) $[y+{\script{1\over 4}}, -x+{\script{3\over 4}}, -z+{\script{3\over 4}}]$ ; (v) $[-y+{\script{1\over 4}}, x-{\script{1\over 4}}, z-{\script{1\over 4}}]$ ; (vi) $[-y+{\script{1\over 4}}, x+{\script{1\over 4}}, -z+{\script{1\over 4}}]$ ; (vii) $[-x+{\script{1\over 2}}, -y, z-{\script{1\over 2}}]$ ; (viii) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ix) $[-x, -y+{\script{1\over 2}}, z]$ ; (x) $[-y-{\script{1\over 4}}, x+{\script{1\over 4}}, z+{\script{1\over 4}}]$ ; (xi) $[y-{\script{1\over 4}}, -x+{\script{1\over 4}}, -z+{\script{1\over 4}}]$ ; (xii) $[y-{\script{1\over 4}}, -x+{\script{3\over 4}}, z-{\script{1\over 4}}]$ ; (xiii) ; (xiv) $[-x+{\script{1\over 2}}, -y, z+{\script{1\over 2}}]$ ; (xv) .

Figure 1
The principal building units in the crystal structure of Sr₉La₂(WO₆)₄ with displacement ellipsoids drawn at the 99% probability level. Symmetry codes refer to Table 1

The Sr/La occupancies for (Sr/La)1 (16f, 1), (Sr/La)2 (16f, 1), (Sr/La)3 (8e, 2..), and (Sr/La)4 (4a, $[\overline{4}]$ ..) are 0.6384/0.3616 (19), 0.8913/0.1087 (18), 0.948/0.052 (4), and 0.985/0.015 (7), respectively. The interatomic distances between (Sr/La) and O and the coordination numbers of the cations are 2.333 (4)–2.861 (4) Å (average: 2.611 Å) and 8 for (Sr/La)1—O; 2.470 (4)–2.877 (5) Å (average: 2.660 Å) and 8 for (Sr/La)2—O; 2.557 (4)–3.220 (4) Å (average: 2.761 Å) and 10 for (Sr/La)3—O; and 2.607 (4)–3.131 (4) Å (average: 2.912 Å) and 12 for (Sr/La)4—O. As the La occupancy increases, the (Sr/La)—O interatomic distance decreases.

The crystal structures of alkaline-earth and rare-earth tungstates are often described in relation to the double-perovskite structure type (Kemmler-Sack & Ehmann, 1981; Betz et al., 1982; Blasse & Kemmler-Sack, 1983; King et al., 2010 ; Ijdo et al., 2016). In the double-perovskite (A₂BB′O₆) structure, B and B′ atoms alternately occupy the B site of the perovskite (ABO₃) structure. The B site is at the center of an octahedron formed by O atoms, and the vertex-sharing [BO₆] and [B′O₆] octahedra regularly align in the A₈ simple cubic lattice frame in the double-perovskite structure. In case of the structure of Sr₉La₂(WO₆)₄, a (Sr/La,□)₈ distorted simple lattice can be derived by connecting the Sr-rich sites of (Sr/La)2, (Sr/La)3, and (Sr/La)4 and a vacancy site at (1/2, 3/4, 1/8), as shown in Fig. 2. In the distorted lattice, the [WO₆] octahedra and the [(Sr/La)1O₈] polyhedra are alternately located by sharing four vertices and two edges of the [(Sr/La)1O₈] polyhedra (Fig. 2).

Figure 2
[WO₆] octahedra and [(Sr/La)1O₈] polyhedra alternately distributed in the distorted (Sr/La2–4,□)₈ lattice as illustrated for the planes parallel to (001) in (a) and (110) in (b). Note that [WO₆] octahedra and [(Sr/La)1O₈] polyhedra are connected to each other by vertex- or edge-sharing.

The crystal structure of Sr₉La₂(WO₆)₄ is isotypic with those of Sr₁₁(ReO₆)₄ [a = 11.6779 (1), c = 16.1488 (2); Bramnik et al., 2000 ], Ba₁₁(OsO₆)₄ [a = 12.2414 (1), c = 16.6685 (1); Wakeshima & Hinatsu, 2005 ], La₉Sr(IrO₆)₄ [a = 11.5955 (11), c = 16.2531 (15); Ferreira et al., 2018 ], and Sr₁₁(MoO₆)₄ [a = 11.6107 (6), c = 16.4219 (13); Löpez et al., 2016 ].

3. Synthesis and crystallization

Raw powdered materials of SrCO₃ (Hakushin Chemical Laboratory, 98%), WO₃ (Furuuchi Chemical, 99.99%), and La₂O₃ (FUJIFILM Wako Pure Chemical, 99.99%; calcined at 1273 K in advance) were weighed in a Sr:La:W molar ratio of 9:2:4, mixed in an agate mortar, and pressed into a cylindrical pellet with a diameter of 6 mm. The pellet was placed on a Pt plate in an alumina crucible with a lid (Nikkato, SSA-S) and heated to 1473 K at a rate of 300 K h⁻¹ in a furnace. This temperature was maintained for 10 h, and the power to the heater of the furnace was then shut off. After the sample had cooled to room temperature, the sintered pellet was crushed, pressed into a pellet, and heated again under the same conditions. This procedure was performed three times. Part of the sintered pellet was then placed on a Pt plate in an alumina crucible, heated at 1673 K for 6 h, and cooled to room temperature at a rate of −400 K h⁻¹. The obtained crystalline sample was an aggregate consisting of ∼50 µm single-crystalline grains. A single crystal selected from the aggregate was placed on top of a glass fiber for X-ray structure analysis. Another single crystal was embedded in resin, mirror polished, and carbon coated in preparation for chemical analysis using an electron microprobe analyzer (EPMA; JEOL JXA-8200). The chemical composition determined by EPMA was Sr: 23.2 (4), La: 4.8 (1), W: 10.3 (3), and O: 61.7 (5) wt%. The Sr:La:W:O atomic ratio of 9.1 (1): 1.9 (1): 4.0 (1): 24.0 (2) calculated from the composition is consistent with the chemical formula Sr₉La₂(WO₆)₄.

4. Refinement

The results of the crystal structure analysis are summarized in Table 2. An initial structure model with two W sites, four Sr sites, and six O sites using isotropic displacement parameters showed residual electron density distribution around the four Sr sites. These sites were changed to Sr/La mixed sites, and their occupancies were refined under consideration of full occupancy, resulting in an Sr:La:W:O atomic ratio of 35.6:8.4:16:96. Given the charge balance, the numbers of Sr and La atoms in the unit cell was constrained to be 36 and 8, respectively.

Table 2
Experimental details

Crystal data
Chemical formula	Sr₉La₂(WO₆)₄
M_r	2185.80
Crystal system, space group	Tetragonal, I4₁/a
Temperature (K)	300
a, c (Å)	11.6365 (3), 16.3040 (4)
V (Å³)	2207.69 (13)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	46.16
Crystal size (mm)	0.05 × 0.04 × 0.03

Data collection
Diffractometer	Bruker D8 QUEST
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.20, 0.33
No. of measured, independent and observed [I > 2σ(I)] reflections	62981, 2106, 1972
R_int	0.048
(sin θ/λ)_max (Å⁻¹)	0.770

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.025, 0.046, 1.37
No. of reflections	2106
No. of parameters	97
No. of restraints	1
Δρ_max, Δρ_min (e Å⁻³)	1.14, −1.50
Computer programs: APEX3 and SAINT (Bruker, 2018 ), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ), VESTA (Momma & Izumi, 2011 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 2182445

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989022006648/wm5650sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989022006648/wm5650Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2018); cell refinement: SAINT (Bruker, 2018); data reduction: SAINT (Bruker, 2018); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: VESTA (Momma & Izumi, 2011); software used to prepare material for publication: publCIF (Westrip, 2010).

Nonastrontium dilanthanum tetrakis[orthotungstate(VI)] top

Crystal data top

Sr₉La₂(WO₆)₄	D_x = 6.576 Mg m⁻³
M_r = 2185.80	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4₁/a	Cell parameters from 9792 reflections
a = 11.6365 (3) Å	θ = 3.5–33.2°
c = 16.3040 (4) Å	µ = 46.16 mm⁻¹
V = 2207.69 (13) Å³	T = 300 K
Z = 4	Granular, translucent colourless
F(000) = 3776	0.05 × 0.04 × 0.03 mm

Data collection top

Bruker D8 QUEST diffractometer	2106 independent reflections
Radiation source: sealed X-ray tube	1972 reflections with I > 2σ(I)
Detector resolution: 7.3910 pixels mm^-1	R_int = 0.048
ω and σcans	θ_max = 33.2°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −17→17
T_min = 0.20, T_max = 0.33	k = −17→17
62981 measured reflections	l = −25→25

Refinement top

Refinement on F²	1 restraint
Least-squares matrix: full	w = 1/[σ²(F_o²) + 62.4087P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.025	(Δ/σ)_max = 0.001
wR(F²) = 0.046	Δρ_max = 1.14 e Å⁻³
S = 1.37	Δρ_min = −1.50 e Å⁻³
2106 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
97 parameters	Extinction coefficient: 0.000055 (5)

Special details top

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

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Sr1	0.20878 (3)	0.22538 (3)	0.53417 (2)	0.00769 (8)	0.6384 (19)
La1	0.20878 (3)	0.22538 (3)	0.53417 (2)	0.00769 (8)	0.3616 (19)
Sr2	0.23647 (4)	0.04341 (4)	0.11357 (3)	0.00718 (9)	0.8913 (18)
La2	0.23647 (4)	0.04341 (4)	0.11357 (3)	0.00718 (9)	0.1087 (18)
Sr3	0.0000	0.2500	0.36535 (4)	0.00934 (14)	0.948 (4)
La3	0.0000	0.2500	0.36535 (4)	0.00934 (14)	0.052 (4)
Sr4	0.0000	0.2500	0.1250	0.0267 (4)	0.985 (7)
La4	0.0000	0.2500	0.1250	0.0267 (4)	0.015 (7)
W1	0.0000	0.0000	0.5000	0.00522 (6)
W2	0.0000	0.0000	0.0000	0.00502 (6)
O1	0.0101 (3)	0.0266 (3)	0.1158 (2)	0.0093 (7)
O2	0.0795 (3)	0.0786 (3)	0.5877 (2)	0.0099 (7)
O3	0.1059 (4)	0.0651 (4)	0.4243 (3)	0.0137 (8)
O4	0.1383 (4)	0.1321 (4)	0.2554 (3)	0.0148 (8)
O5	0.3675 (3)	0.1315 (3)	0.2308 (2)	0.0109 (7)
O6	0.4011 (3)	0.1285 (3)	0.0246 (2)	0.0096 (7)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sr1	0.00728 (15)	0.00640 (15)	0.00939 (16)	0.00166 (12)	−0.00049 (12)	0.00060 (12)
La1	0.00728 (15)	0.00640 (15)	0.00939 (16)	0.00166 (12)	−0.00049 (12)	0.00060 (12)
Sr2	0.00722 (17)	0.00602 (17)	0.00830 (18)	−0.00036 (14)	0.00015 (14)	−0.00025 (14)
La2	0.00722 (17)	0.00602 (17)	0.00830 (18)	−0.00036 (14)	0.00015 (14)	−0.00025 (14)
Sr3	0.0127 (3)	0.0080 (3)	0.0074 (3)	−0.0024 (2)	0.000	0.000
La3	0.0127 (3)	0.0080 (3)	0.0074 (3)	−0.0024 (2)	0.000	0.000
Sr4	0.0091 (3)	0.0091 (3)	0.0620 (10)	0.000	0.000	0.000
La4	0.0091 (3)	0.0091 (3)	0.0620 (10)	0.000	0.000	0.000
W1	0.00463 (11)	0.00540 (11)	0.00562 (11)	−0.00008 (8)	0.00033 (8)	0.00085 (8)
W2	0.00472 (11)	0.00554 (11)	0.00480 (11)	0.00064 (8)	−0.00001 (8)	−0.00041 (8)
O1	0.0062 (14)	0.0135 (17)	0.0081 (16)	−0.0004 (12)	−0.0012 (12)	−0.0019 (13)
O2	0.0116 (16)	0.0106 (16)	0.0073 (16)	−0.0022 (13)	0.0000 (13)	−0.0007 (13)
O3	0.0128 (17)	0.0134 (18)	0.0149 (19)	0.0023 (14)	0.0071 (14)	0.0062 (14)
O4	0.0184 (19)	0.0141 (18)	0.0118 (18)	−0.0098 (15)	0.0025 (15)	−0.0006 (15)
O5	0.0117 (17)	0.0112 (17)	0.0098 (17)	0.0032 (13)	0.0018 (13)	0.0006 (13)
O6	0.0097 (16)	0.0092 (16)	0.0098 (16)	0.0027 (12)	−0.0009 (13)	−0.0005 (13)

Geometric parameters (Å, º) top

Sr1/La1—O6ⁱ	2.333 (4)	Sr3/La3—O1^xi	3.220 (4)
Sr1/La1—O2	2.438 (4)	Sr3/La3—W2^xi	3.4641 (4)
Sr1/La1—O2ⁱⁱ	2.453 (4)	Sr3/La3—W2ⁱⁱⁱ	3.4641 (4)
Sr1/La1—O4ⁱⁱⁱ	2.458 (4)	Sr4/La4—O1	2.607 (4)
Sr1/La1—O5^iv	2.728 (4)	Sr4/La4—O1^vii	2.607 (4)
Sr1/La1—O3ⁱⁱⁱ	2.765 (5)	Sr4/La4—O1^xii	2.607 (4)
Sr1/La1—O3	2.849 (5)	Sr4/La4—O1^x	2.607 (4)
Sr1/La1—O1ⁱⁱⁱ	2.861 (4)	Sr4/La4—O4	2.998 (5)
Sr1/La1—Sr2/La2^v	3.4446 (6)	Sr4/La4—O4^xii	2.998 (5)
Sr1/La1—Sr2/La2^v	3.4446 (6)	Sr4/La4—O4^x	2.998 (5)
Sr1/La1—W1ⁱⁱⁱ	3.5630 (4)	Sr4/La4—O4^vii	2.998 (5)
Sr1/La1—W1	3.6181 (4)	Sr4/La4—O5ⁱ	3.131 (4)
Sr2/La2—O3^vi	2.470 (4)	Sr4/La4—O5^xiii	3.131 (4)
Sr2/La2—O1^vii	2.548 (4)	Sr4/La4—O5^vi	3.131 (4)
Sr2/La2—O6	2.599 (4)	Sr4/La4—O5^ix	3.131 (4)
Sr2/La2—O2^viii	2.603 (4)	W1—O3	1.901 (4)
Sr2/La2—O1	2.642 (4)	W1—O3^xiv	1.901 (4)
Sr2/La2—O5	2.652 (4)	W1—O6^ix	1.930 (4)
Sr2/La2—O5^vi	2.704 (4)	W1—O6^v	1.930 (4)
Sr2/La2—O4	2.777 (4)	W1—O2	1.934 (4)
Sr2/La2—O4^vi	2.877 (5)	W1—O2^xiv	1.934 (4)
Sr2/La2—W2ⁱⁱⁱ	3.2790 (4)	W1—Sr1/La1^xv	3.5629 (4)
Sr2/La2—W2	3.3549 (4)	W1—Sr1/La1^vi	3.5629 (4)
Sr2/La2—Sr1^viii	3.4446 (6)	W1—Sr2/La2^ix	3.6177 (4)
Sr3/La3—O6ⁱ	2.557 (4)	W1—Sr2/La2^v	3.6177 (4)
Sr3/La3—O6^ix	2.557 (4)	W2—O4^xii	1.891 (4)
Sr3/La3—O5^ix	2.596 (4)	W2—O4^vi	1.891 (4)
Sr3/La3—O5ⁱ	2.596 (4)	W2—O1^xvi	1.917 (4)
Sr3/La3—O3	2.660 (4)	W2—O1	1.917 (4)
Sr3/La3—O3^x	2.660 (4)	W2—O5^xii	1.967 (4)
Sr3/La3—O4^x	2.773 (4)	W2—O5^vi	1.967 (4)
Sr3/La3—O4	2.773 (4)	W2—Sr2/La2^xii	3.2790 (4)
Sr3/La3—O1ⁱⁱⁱ	3.220 (4)	W2—Sr2/La2^vi	3.2790 (4)

O6ⁱ—Sr1/La1—O2	108.65 (13)	W2^xi—Sr3/La3—W2ⁱⁱⁱ	114.236 (19)
O6ⁱ—Sr1/La1—O2ⁱⁱ	83.84 (13)	O1—Sr4/La4—O1^vii	90.189 (10)
O2—Sr1/La1—O2ⁱⁱ	86.10 (14)	O1—Sr4/La4—O1^xii	90.189 (10)
O6ⁱ—Sr1/La1—O4ⁱⁱⁱ	139.77 (14)	O1^vii—Sr4/La4—O1^xii	173.41 (17)
O2—Sr1/La1—O4ⁱⁱⁱ	101.40 (14)	O1—Sr4/La4—O1^x	173.41 (17)
O2ⁱⁱ—Sr1/La1—O4ⁱⁱⁱ	125.03 (13)	O1^vii—Sr4/La4—O1^x	90.189 (10)
O6ⁱ—Sr1/La1—O5^iv	83.02 (13)	O1^xii—Sr4/La4—O1^x	90.189 (10)
O2—Sr1/La1—O5^iv	163.00 (12)	O1—Sr4/La4—O4	63.92 (11)
O2ⁱⁱ—Sr1/La1—O5^iv	82.86 (13)	O1^vii—Sr4/La4—O4	56.25 (11)
O4ⁱⁱⁱ—Sr1/La1—O5^iv	74.87 (14)	O1^xii—Sr4/La4—O4	118.30 (11)
O6ⁱ—Sr1/La1—O3ⁱⁱⁱ	146.51 (13)	O1^x—Sr4/La4—O4	121.40 (11)
O2—Sr1/La1—O3ⁱⁱⁱ	74.94 (12)	O1—Sr4/La4—O4^xii	56.25 (11)
O2ⁱⁱ—Sr1/La1—O3ⁱⁱⁱ	62.93 (12)	O1^vii—Sr4/La4—O4^xii	121.40 (11)
O4ⁱⁱⁱ—Sr1/La1—O3ⁱⁱⁱ	66.83 (13)	O1^xii—Sr4/La4—O4^xii	63.92 (11)
O5^iv—Sr1/La1—O3ⁱⁱⁱ	88.51 (12)	O1^x—Sr4/La4—O4^xii	118.30 (11)
O6ⁱ—Sr1/La1—O3	89.34 (13)	O4—Sr4/La4—O4^xii	120.17 (10)
O2—Sr1/La1—O3	60.49 (12)	O1—Sr4/La4—O4^x	121.40 (11)
O2ⁱⁱ—Sr1/La1—O3	141.63 (12)	O1^vii—Sr4/La4—O4^x	118.30 (11)
O4ⁱⁱⁱ—Sr1/La1—O3	82.66 (13)	O1^xii—Sr4/La4—O4^x	56.25 (11)
O5^iv—Sr1/La1—O3	133.77 (12)	O1^x—Sr4/La4—O4^x	63.92 (11)
O3ⁱⁱⁱ—Sr1/La1—O3	118.90 (13)	O4—Sr4/La4—O4^x	89.71 (17)
O6ⁱ—Sr1/La1—O1ⁱⁱⁱ	73.37 (12)	O4^xii—Sr4/La4—O4^x	120.17 (10)
O2—Sr1/La1—O1ⁱⁱⁱ	123.73 (12)	O1—Sr4/La4—O4^vii	118.30 (11)
O2ⁱⁱ—Sr1/La1—O1ⁱⁱⁱ	146.75 (12)	O1^vii—Sr4/La4—O4^vii	63.92 (11)
O4ⁱⁱⁱ—Sr1/La1—O1ⁱⁱⁱ	67.80 (12)	O1^xii—Sr4/La4—O4^vii	121.40 (11)
O5^iv—Sr1/La1—O1ⁱⁱⁱ	70.80 (11)	O1^x—Sr4/La4—O4^vii	56.25 (11)
O3ⁱⁱⁱ—Sr1/La1—O1ⁱⁱⁱ	133.60 (11)	O4—Sr4/La4—O4^vii	120.17 (10)
O3—Sr1/La1—O1ⁱⁱⁱ	63.35 (11)	O4^xii—Sr4/La4—O4^vii	89.71 (17)
Sr2/La2^v—Sr1/La1—W1	61.565 (10)	O4^x—Sr4/La4—O4^vii	120.17 (10)
W1ⁱⁱⁱ—Sr1/La1—W1	107.502 (10)	O1—Sr4/La4—O5ⁱ	117.41 (11)
O3^vi—Sr2/La2—O1^vii	143.76 (14)	O1^vii—Sr4/La4—O5ⁱ	56.35 (11)
O3^vi—Sr2/La2—O6	137.69 (13)	O1^xii—Sr4/La4—O5ⁱ	117.90 (11)
O1^vii—Sr2/La2—O6	74.95 (12)	O1^x—Sr4/La4—O5ⁱ	68.03 (11)
O3^vi—Sr2/La2—O2^viii	77.47 (13)	O4—Sr4/La4—O5ⁱ	53.49 (10)
O1^vii—Sr2/La2—O2^viii	127.58 (12)	O4^xii—Sr4/La4—O5ⁱ	173.65 (10)
O6—Sr2/La2—O2^viii	60.75 (12)	O4^x—Sr4/La4—O5ⁱ	62.02 (10)
O3^vi—Sr2/La2—O1	71.74 (13)	O4^vii—Sr4/La4—O5ⁱ	94.03 (11)
O1^vii—Sr2/La2—O1	90.70 (17)	O1—Sr4/La4—O5^xiii	117.90 (11)
O6—Sr2/La2—O1	140.44 (12)	O1^vii—Sr4/La4—O5^xiii	117.41 (11)
O2^viii—Sr2/La2—O1	141.44 (12)	O1^xii—Sr4/La4—O5^xiii	68.03 (11)
O3^vi—Sr2/La2—O5	101.06 (13)	O1^x—Sr4/La4—O5^xiii	56.35 (11)
O1^vii—Sr2/La2—O5	63.69 (12)	O4—Sr4/La4—O5^xiii	173.65 (10)
O6—Sr2/La2—O5	80.29 (12)	O4^xii—Sr4/La4—O5^xiii	62.02 (10)
O2^viii—Sr2/La2—O5	81.63 (12)	O4^x—Sr4/La4—O5^xiii	94.03 (11)
O1—Sr2/La2—O5	126.30 (12)	O4^vii—Sr4/La4—O5^xiii	53.49 (10)
O3^vi—Sr2/La2—O5^vi	118.64 (12)	O5ⁱ—Sr4/La4—O5^xiii	124.29 (9)
O1^vii—Sr2/La2—O5^vi	76.11 (12)	O1—Sr4/La4—O5^vi	56.35 (11)
O6—Sr2/La2—O5^vi	78.82 (12)	O1^vii—Sr4/La4—O5^vi	68.03 (11)
O2^viii—Sr2/La2—O5^vi	117.51 (12)	O1^xii—Sr4/La4—O5^vi	117.41 (11)
O1—Sr2/La2—O5^vi	61.87 (12)	O1^x—Sr4/La4—O5^vi	117.90 (11)
O5—Sr2/La2—O5^vi	138.23 (9)	O4—Sr4/La4—O5^vi	94.03 (11)
O3^vi—Sr2/La2—O4	83.96 (13)	O4^xii—Sr4/La4—O5^vi	53.49 (10)
O1^vii—Sr2/La2—O4	59.86 (12)	O4^x—Sr4/La4—O5^vi	173.65 (10)
O6—Sr2/La2—O4	128.74 (12)	O4^vii—Sr4/La4—O5^vi	62.02 (10)
O2^viii—Sr2/La2—O4	132.50 (13)	O5ⁱ—Sr4/La4—O5^vi	124.29 (9)
O1—Sr2/La2—O4	66.80 (12)	O5^xiii—Sr4/La4—O5^vi	82.71 (14)
O5—Sr2/La2—O4	59.51 (12)	O1—Sr4/La4—O5^ix	68.03 (11)
O5^vi—Sr2/La2—O4	109.81 (13)	O1^vii—Sr4/La4—O5^ix	117.90 (11)
O3^vi—Sr2/La2—O4^vi	64.87 (13)	O1^xii—Sr4/La4—O5^ix	56.35 (11)
O1^vii—Sr2/La2—O4^vi	132.31 (11)	O1^x—Sr4/La4—O5^ix	117.41 (11)
O6—Sr2/La2—O4^vi	104.51 (12)	O4—Sr4/La4—O5^ix	62.02 (10)
O2^viii—Sr2/La2—O4^vi	87.33 (12)	O4^xii—Sr4/La4—O5^ix	94.03 (11)
O1—Sr2/La2—O4^vi	58.90 (11)	O4^x—Sr4/La4—O5^ix	53.49 (10)
O5—Sr2/La2—O4^vi	163.87 (12)	O4^vii—Sr4/La4—O5^ix	173.65 (10)
O5^vi—Sr2/La2—O4^vi	57.69 (11)	O5ⁱ—Sr4/La4—O5^ix	82.71 (14)
O4—Sr2/La2—O4^vi	123.12 (9)	O5^xiii—Sr4/La4—O5^ix	124.29 (9)
W2ⁱⁱⁱ—Sr2/La2—W2	121.613 (13)	O5^vi—Sr4/La4—O5^ix	124.29 (9)
W2ⁱⁱⁱ—Sr2/La2—Sr1/La1^viii	155.754 (16)	O3—W1—O3^xiv	180.0
W2—Sr2/La2—Sr1/La1^viii	78.905 (11)	O3—W1—O6^ix	86.73 (17)
O6ⁱ—Sr3/La3—O6^ix	90.91 (18)	O3^xiv—W1—O6^ix	93.27 (17)
O6ⁱ—Sr3/La3—O5^ix	169.96 (12)	O3—W1—O6^v	93.27 (17)
O6^ix—Sr3/La3—O5^ix	82.12 (12)	O3^xiv—W1—O6^v	86.73 (17)
O6ⁱ—Sr3/La3—O5ⁱ	82.12 (12)	O6^ix—W1—O6^v	180.0 (2)
O6^ix—Sr3/La3—O5ⁱ	169.96 (12)	O3—W1—O2	88.94 (18)
O5^ix—Sr3/La3—O5ⁱ	105.66 (18)	O3^xiv—W1—O2	91.06 (18)
O6ⁱ—Sr3/La3—O3	89.14 (13)	O6^ix—W1—O2	94.18 (16)
O6^ix—Sr3/La3—O3	60.52 (12)	O6^v—W1—O2	85.82 (16)
O5^ix—Sr3/La3—O3	93.66 (13)	O3—W1—O2^xiv	91.07 (18)
O5ⁱ—Sr3/La3—O3	111.89 (12)	O3^xiv—W1—O2^xiv	88.93 (18)
O6ⁱ—Sr3/La3—O3^x	60.52 (12)	O6^ix—W1—O2^xiv	85.82 (16)
O6^ix—Sr3/La3—O3^x	89.14 (13)	O6^v—W1—O2^xiv	94.18 (16)
O5^ix—Sr3/La3—O3^x	111.89 (12)	O2—W1—O2^xiv	180.0
O5ⁱ—Sr3/La3—O3^x	93.66 (13)	Sr1/La1^xv—W1—Sr1/La1^vi	180.0
O3—Sr3/La3—O3^x	137.62 (19)	Sr1/La1^vi—W1—Sr1/La1^vi	0.0
O6ⁱ—Sr3/La3—O4^x	116.21 (12)	Sr1/La1^xv—W1—Sr1/La1^xv	0.0
O6^ix—Sr3/La3—O4^x	117.76 (12)	Sr1/La1^vi—W1—Sr1/La1^xv	180.0
O5^ix—Sr3/La3—O4^x	61.78 (12)	Sr1/La1^xv—W1—Sr2/La2^ix	114.745 (9)
O5ⁱ—Sr3/La3—O4^x	72.02 (12)	Sr1/La1^vi—W1—Sr2/La2^ix	65.255 (9)
O3—Sr3/La3—O4^x	154.56 (13)	Sr1/La1^xv—W1—Sr2/La2^ix	114.745 (9)
O3^x—Sr3/La3—O4^x	64.19 (13)	Sr1/La1^xv—W1—Sr2/La2^v	65.255 (9)
O6ⁱ—Sr3/La3—O4	117.76 (12)	Sr1/La1^vi—W1—Sr2/La2^v	114.745 (9)
O6^ix—Sr3/La3—O4	116.21 (12)	Sr2/La2^ix—W1—Sr2/La2^v	180.000 (12)
O5^ix—Sr3/La3—O4	72.02 (12)	O4^xii—W2—O4^vi	180.0 (3)
O5ⁱ—Sr3/La3—O4	61.78 (12)	O4^xii—W2—O1^xvi	91.21 (17)
O3—Sr3/La3—O4	64.19 (13)	O4^vi—W2—O1^xvi	88.79 (17)
O3^x—Sr3/La3—O4	154.56 (13)	O4^xii—W2—O1	88.80 (17)
O4^x—Sr3/La3—O4	99.40 (19)	O4^vi—W2—O1	91.20 (17)
O6ⁱ—Sr3/La3—O1ⁱⁱⁱ	64.45 (11)	O1^xvi—W2—O1	180.0
O6^ix—Sr3/La3—O1ⁱⁱⁱ	115.34 (11)	O4^xii—W2—O5^xii	88.65 (18)
O5^ix—Sr3/La3—O1ⁱⁱⁱ	125.14 (11)	O4^vi—W2—O5^xii	91.35 (18)
O5ⁱ—Sr3/La3—O1ⁱⁱⁱ	55.05 (11)	O1^xvi—W2—O5^xii	90.08 (16)
O3—Sr3/La3—O1ⁱⁱⁱ	60.43 (11)	O1—W2—O5^xii	89.92 (16)
O3^x—Sr3/La3—O1ⁱⁱⁱ	119.46 (11)	O4^xii—W2—O5^vi	91.35 (18)
O4^x—Sr3/La3—O1ⁱⁱⁱ	126.84 (11)	O4^vi—W2—O5^vi	88.65 (18)
O4—Sr3/La3—O1ⁱⁱⁱ	53.37 (11)	O1^xvi—W2—O5^vi	89.92 (16)
O6ⁱ—Sr3/La3—O1^xi	115.34 (11)	O1—W2—O5^vi	90.08 (16)
O6^ix—Sr3/La3—O1^xi	64.45 (11)	O5^xii—W2—O5^vi	180.0 (3)
O5^ix—Sr3/La3—O1^xi	55.05 (11)	Sr2/La2^xii—W2—Sr2/La2^vi	180.0
O5ⁱ—Sr3/La3—O1^xi	125.14 (11)	Sr2/La2^xii—W2—Sr2/La2^xii	0.0
O3—Sr3/La3—O1^xi	119.46 (11)	Sr2/La2^vi—W2—Sr2/La2^xii	180.00 (2)
O3^x—Sr3/La3—O1^xi	60.43 (11)	Sr2/La2^vi—W2—Sr2/La2^vi	0.000 (11)
O4^x—Sr3/La3—O1^xi	53.37 (11)	Sr2/La2^xii—W2—Sr2/La2	102.7
O4—Sr3/La3—O1^xi	126.84 (11)	Sr2/La2^vi—W2—Sr2/La2	77.309 (8)
O1ⁱⁱⁱ—Sr3/La3—O1^xi	179.73 (14)	Sr2/La2^xii—W2—Sr2/La2	102.691 (8)

Symmetry codes: (i) −x+1/2, −y+1/2, −z+1/2; (ii) −y+1/4, x+1/4, −z+5/4; (iii) y+1/4, −x+1/4, z+1/4; (iv) y+1/4, −x+3/4, −z+3/4; (v) −x+1/2, −y, z+1/2; (vi) −y+1/4, x−1/4, z−1/4; (vii) −y+1/4, x+1/4, −z+1/4; (viii) −x+1/2, −y, z−1/2; (ix) x−1/2, y, −z+1/2; (x) −x, −y+1/2, z; (xi) −y−1/4, x+1/4, z+1/4; (xii) y−1/4, −x+1/4, −z+1/4; (xiii) y−1/4, −x+3/4, z−1/4; (xiv) −x, −y, −z+1; (xv) y−1/4, −x+1/4, −z+5/4; (xvi) −x, −y, −z.

Acknowledgements

We thank Mr I. Narita (Institute for Materials Research, Tohoku University) for carrying out the EPMA under the following cooperative research grant (No. 202112-CRKEQ-0208).

Funding information

Funding for this research was provided by: JSPS KAKENHI (grant No. JP20K20363); the Cooperative Research of the Development Center for Advanced Materials, Institute for Materials Research, Tohoku University (grant No. 202112-CRKEQ-0208); the Tohoku University Center for Gender Equality Promotion Support Project.

References

Betz, B., Schittenhelm, H. J. & Kemmler-Sack, S. (1982). Z. Anorg. Allg. Chem. 484, 177–186. CrossRef ICSD CAS Web of Science Google Scholar
Blasse, G. & Kemmler-Sack, S. (1983). Ber. Bunsenges. Phys. Chem. 87, 698–701. CrossRef CAS Web of Science Google Scholar
Bramnik, K. G., Miehe, G., Ehrenberg, H., Fuess, H., Abakumov, A. M., Shpanchenko, R. V., Pomjakushin, V. Y. & Balagurov, A. M. (2000). J. Solid State Chem. 149, 49–55. Web of Science CrossRef ICSD CAS Google Scholar
Brese, N. E. & O'Keeffe, M. (1991). Acta Cryst. B47, 192–197. CrossRef CAS Web of Science IUCr Journals Google Scholar
Brown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244–247. CrossRef CAS Web of Science IUCr Journals Google Scholar
Bruker (2018). APEX3 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Ferreira, T., Smith, M. D. & zur Loye, H.-C. (2018). Inorg. Chem. 57, 7797–7804. Web of Science CrossRef ICSD CAS PubMed Google Scholar
Ijdo, D. J. W., Fu, W. T. & Akerboom, S. (2016). J. Solid State Chem. 238, 236–240. Web of Science CrossRef ICSD CAS Google Scholar
Kemmler-Sack, S. & Ehmann, A. (1981). Z. Anorg. Allg. Chem. 479, 184–190. CAS Google Scholar
King, G., Abakumov, A. M., Hadermann, J., Alekseeva, A. M., Rozova, M. G., Perkisas, T., Woodward, P., Van Tendeloo, G. & Antipov, E. V. (2010). Inorg. Chem. 49, 6058–6065. Web of Science CrossRef ICSD CAS PubMed Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef ICSD CAS IUCr Journals Google Scholar
López, C. A., Pedregosa, J. C., Fernández-Díaz, M. T. & Alonso, J. A. (2016). J. Appl. Cryst. 49, 78–84. Web of Science CrossRef ICSD IUCr Journals Google Scholar
Momma, K. & Izumi, F. (2011). J. Appl. Cryst. 44, 1272–1276. Web of Science CrossRef CAS IUCr Journals Google Scholar
Qin, C., Huang, Y. & Seo, H. J. (2012). J. Alloys Compd. 534, 86–92. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shi, L., Han, Y.-J., Wang, H.-X., Shi, D.-C., Geng, X.-Y. & Zhang, Z.-W. (2019). J. Lumin. 208, 307–312. Web of Science CrossRef CAS Google Scholar
Smirnov, S. A., Evdokimov, A. A. & Kovba, L. M. (1987). Dokl. Akad. Nauk SSSR, 292, 99–102. CAS Google Scholar
Wakeshima, M. & Hinatsu, Y. (2005). Solid State Commun. 136, 499–503. Web of Science CrossRef ICSD CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zeng, Q., He, P., Zhang, X., Liang, H., Gong, M. & Su, Q. (2009). Chem. Lett. 38, 1172–1173. Web of Science CrossRef CAS Google Scholar
Zeng, Q., Liang, H. & Gong, M. (2013). Asian J. Chem. 25, 5971–5974. Web of Science CrossRef CAS Google Scholar
Zeng, Q.-H., Zhang, X.-G., He, P., Liang, H.-B. & Gong, M.-L. (2010). J. Inorg. Mater. 25, 1009–1014. Web of Science CrossRef CAS Google Scholar
Zhou, F., Gao, M., Shi, Y., Li, Z., Zhu, G., Xin, S. & Wang, C. (2020). J. Lumin. 223, 117235. Web of Science CrossRef Google Scholar