Crystal growth and twinned crystal structure of Sr₂CaWO₆

Single crystals of Sr₂CaWO₆ have been prepared by sintering at high temperature. Powder samples were compressed into rods and heated up to 1953 K. This seems a promising new route for further studies of the structure and physical properties of double perovskites. The structural model of Sr₂CaWO₆ includes a quantitative description of the twinning shown by the diffraction pattern that should be present in almost any single-crystal specimen for this type of compound.

Computing details

Program(s) used to refine structure: Jana2000 (Petricek, Dusek & Palatinus, 2000); software used to prepare material for publication: Jana2000 (Petricek, Dusek & Palatinus, 2000).

(I)

Crystal data

Ca0.5O3SrW0.5	Z = 4
Mr = 247.6	F(000) = 436
Monoclinic, P21/n	Dx = 5.941 Mg m^−3
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71069 Å
a = 5.800 (2) Å	µ = 40.83 mm^−1
b = 5.813 (2) Å	T = 293 K
c = 8.207 (5) Å	Irregular prism, light orange
β = 89.966 (5)°	0.12 × 0.08 × 0.05 mm
V = 276.7 (2) Å^3

Data collection

Stoe IPDS I diffractometer	566 independent reflections
Radiation source: sealed X-ray tube	350 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.096
150 images at 2^o stepwise rotation in phi, 16min./frame scans	θmax = 25.9°, θmin = 4.3°
Absorption correction: analytical (see. N.W. Alcock (1970). Cryst. Computing, p271)	h = −7→7
Tmin = 0.071, Tmax = 0.178	k = −7→7
1910 measured reflections	l = −10→10

Refinement

Refinement on F^2	12 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.042	Secondary atom site location: difference Fourier map
wR(F^2) = 0.134	Weighting scheme based on measured s.u.'s w = 1/(σ^2(I) + 0.0081I^2)
S = 1.04	(Δ/σ)max = 0.001
566 reflections	Δρmax = 2.32 e Å^−3
25 parameters	Δρmin = −2.51 e Å^−3

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

	x	y	z	Uiso*/Ueq
Sr	0.0010 (19)	0.5358 (10)	0.2502 (10)	0.0086 (16)
Ca	0	0	0.5	0.0053 (11)*
W	0	0	0	0.0027 (4)*
O1	0.079 (5)	0.018 (4)	−0.224 (5)	0.038 (4)*
O2	0.277 (3)	−0.169 (4)	0.042 (3)	0.038 (4)*
O3	0.161 (4)	0.283 (3)	0.040 (3)	0.038 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sr	0.013 (3)	0.012 (2)	0.001 (3)	0	0	0

Geometric parameters (Å, º)

Sr—O1^i	2.64 (3)	Ca—O2^viii	2.34 (2)
Sr—O1^ii	2.48 (3)	W—O1	1.90 (4)
Sr—O3	2.45 (3)	W—O1^vi	1.90 (4)
Sr—O3^i	2.77 (3)	W—O3	1.917 (18)
Sr—O3^iii	2.98 (3)	W—O3^vi	1.917 (18)
Sr—O2^iv	2.90 (2)	W—O2	1.92 (2)
Sr—O2^iii	2.45 (2)	W—O2^vi	1.92 (2)
Sr—O2^ii	2.83 (3)	O1—O3	2.70 (4)
Ca—O1^v	2.31 (4)	O1—O3^vi	2.70 (4)
Ca—O1^vi	2.31 (4)	O1—O2	2.70 (4)
Ca—O3^vii	2.36 (2)	O1—O2^vi	2.70 (4)
Ca—O3^ii	2.36 (2)	O3—O2	2.71 (3)
Ca—O2^iii	2.34 (2)	O3—O2^vi	2.71 (3)
O1^i—Sr—O1^ii	87.6 (9)	Ca^x—O1—O2^vi	114.0 (12)
O1^i—Sr—O3	126.7 (10)	W—O1—O3	45.3 (9)
O1^i—Sr—O3^i	59.8 (9)	W—O1—O3^vi	45.3 (8)
O1^i—Sr—O3^iii	71.9 (8)	W—O1—O2	45.3 (9)
O1^i—Sr—O2^iv	58.0 (9)	W—O1—O2^vi	45.3 (8)
O1^i—Sr—O2^iii	128.8 (10)	O3—O1—O3^vi	90.6 (13)
O1^i—Sr—O2^ii	73.7 (10)	O3—O1—O2	60.4 (10)
O1^ii—Sr—O1^i	87.6 (9)	O3—O1—O2^vi	60.3 (10)
O1^ii—Sr—O3	110.9 (10)	O3^vi—O1—O3	90.6 (13)
O1^ii—Sr—O3^i	77.7 (10)	O3^vi—O1—O2	60.3 (10)
O1^ii—Sr—O3^iii	131.5 (10)	O3^vi—O1—O2^vi	60.4 (10)
O1^ii—Sr—O2^iv	132.1 (9)	O2—O1—O2^vi	90.6 (13)
O1^ii—Sr—O2^iii	113.4 (10)	O2^vi—O1—O2	90.6 (13)
O1^ii—Sr—O2^ii	60.7 (10)	Sr—O3—Sr^i	104.4 (7)
O3—Sr—O3^i	75.6 (7)	Sr—O3—Sr^vii	97.5 (9)
O3—Sr—O3^iii	116.6 (8)	Sr—O3—Ca^iii	95.2 (7)
O3—Sr—O2^iv	74.4 (7)	Sr—O3—W	116.9 (11)
O3—Sr—O2^iii	90.0 (8)	Sr—O3—O1	147.3 (11)
O3—Sr—O2^ii	159.0 (8)	Sr—O3—O1^vi	78.5 (10)
O3^i—Sr—O3	75.6 (7)	Sr—O3—O2	132.2 (12)
O3^i—Sr—O3^iii	122.5 (6)	Sr—O3—O2^vi	88.1 (9)
O3^i—Sr—O2^iv	57.0 (6)	Sr^i—O3—Sr	104.4 (7)
O3^i—Sr—O2^iii	164.5 (8)	Sr^i—O3—Sr^vii	154.7 (10)
O3^i—Sr—O2^ii	117.9 (7)	Sr^i—O3—Ca^iii	87.7 (8)
O3^iii—Sr—O3	116.6 (8)	Sr^i—O3—W	90.9 (10)
O3^iii—Sr—O3^i	122.5 (6)	Sr^i—O3—O1	57.8 (8)
O3^iii—Sr—O2^iv	72.1 (7)	Sr^i—O3—O1^vi	123.7 (11)
O3^iii—Sr—O2^iii	59.0 (7)	Sr^i—O3—O2	117.3 (10)
O3^iii—Sr—O2^ii	71.4 (7)	Sr^i—O3—O2^vi	64.0 (8)
O2^iv—Sr—O2^iii	114.1 (7)	Sr^vii—O3—Sr	97.5 (9)
O2^iv—Sr—O2^ii	126.1 (7)	Sr^vii—O3—Sr^i	154.7 (10)
O2^iii—Sr—O2^iv	114.1 (7)	Sr^vii—O3—Ca^iii	77.8 (7)
O2^iii—Sr—O2^ii	77.6 (7)	Sr^vii—O3—W	90.3 (7)
O2^ii—Sr—O2^iv	126.1 (7)	Sr^vii—O3—O1	107.8 (8)
O2^ii—Sr—O2^iii	77.6 (7)	Sr^vii—O3—O1^vi	72.7 (9)
O1^v—Ca—O1^vi	180	Sr^vii—O3—O2	50.6 (6)
O1^v—Ca—O3^vii	89.7 (10)	Sr^vii—O3—O2^vi	130.1 (9)
O1^v—Ca—O3^ii	90.3 (10)	Ca^iii—O3—W	147.1 (12)
O1^v—Ca—O2^iii	89.8 (9)	Ca^iii—O3—O1	109.9 (12)
O1^v—Ca—O2^viii	90.2 (9)	Ca^iii—O3—O1^vi	148.6 (13)
O1^vi—Ca—O1^v	180	Ca^iii—O3—O2	108.1 (9)
O1^vi—Ca—O3^vii	90.3 (10)	Ca^iii—O3—O2^vi	151.4 (12)
O1^vi—Ca—O3^ii	89.7 (10)	W—O3—O2^vi	45.1 (7)
O1^vi—Ca—O2^iii	90.2 (9)	O1—O3—O1^vi	89.4 (11)
O1^vi—Ca—O2^viii	89.8 (9)	O1—O3—O2	59.8 (9)
O3^vii—Ca—O3^ii	180	O1—O3—O2^vi	59.8 (9)
O3^vii—Ca—O2^iii	87.6 (7)	O1^vi—O3—O1	89.4 (11)
O3^vii—Ca—O2^viii	92.4 (7)	O1^vi—O3—O2	59.8 (8)
O3^ii—Ca—O3^vii	180	O1^vi—O3—O2^vi	59.9 (10)
O3^ii—Ca—O2^iii	92.4 (7)	O2—O3—O2^vi	90
O3^ii—Ca—O2^viii	87.6 (7)	O2^vi—O3—O2	90
O2^iii—Ca—O2^viii	180	Sr^xi—O2—Sr^vii	99.6 (8)
O2^viii—Ca—O2^iii	180	Sr^xi—O2—Sr^ix	155.9 (10)
O1—W—O1^vi	180	Sr^xi—O2—Ca^vii	84.6 (8)
O1—W—O3	90.0 (11)	Sr^xi—O2—W	86.9 (7)
O1—W—O3^vi	90.0 (11)	Sr^xi—O2—O1	118.6 (9)
O1—W—O2	90.0 (11)	Sr^xi—O2—O1^vi	56.1 (7)
O1—W—O2^vi	90.0 (11)	Sr^xi—O2—O3	115.9 (9)
O1^vi—W—O1	180	Sr^xi—O2—O3^vi	59.0 (7)
O1^vi—W—O3	90.0 (11)	Sr^vii—O2—Sr^xi	99.6 (8)
O1^vi—W—O3^vi	90.0 (11)	Sr^vii—O2—Sr^ix	102.4 (8)
O1^vi—W—O2	90.0 (11)	Sr^vii—O2—Ca^vii	102.3 (8)
O1^vi—W—O2^vi	90.0 (11)	Sr^vii—O2—W	108.4 (11)
O3—W—O3^vi	180	Sr^vii—O2—O1	126.3 (12)
O3—W—O2	90.1 (10)	Sr^vii—O2—O1^vi	81.8 (10)
O3—W—O2^vi	89.9 (10)	Sr^vii—O2—O3	70.3 (9)
O3^vi—W—O3	180	Sr^vii—O2—O3^vi	141.6 (11)
O3^vi—W—O2	89.9 (10)	Sr^ix—O2—Sr^xi	155.9 (10)
O3^vi—W—O2^vi	90.1 (10)	Sr^ix—O2—Sr^vii	102.4 (8)
O2—W—O2^vi	180	Sr^ix—O2—Ca^vii	81.3 (7)
O2^vi—W—O2	180	Sr^ix—O2—W	95.3 (10)
Sr^i—O1—Sr^ix	106.9 (10)	Sr^ix—O2—O1	53.2 (8)
Sr^i—O1—Ca^x	86.0 (10)	Sr^ix—O2—O1^vi	136.9 (12)
Sr^i—O1—W	95.3 (12)	Sr^ix—O2—O3	81.0 (9)
Sr^i—O1—O3	62.4 (8)	Sr^ix—O2—O3^vi	106.7 (10)
Sr^i—O1—O3^vi	126.3 (13)	Ca^vii—O2—W	149.2 (12)
Sr^i—O1—O2	122.5 (14)	Ca^vii—O2—O1	116.7 (12)
Sr^i—O1—O2^vi	65.9 (9)	Ca^vii—O2—O1^vi	140.4 (12)
Sr^ix—O1—Sr^i	106.9 (10)	Ca^vii—O2—O3	158.8 (11)
Sr^ix—O1—Ca^x	96.1 (12)	Ca^vii—O2—O3^vi	106.3 (10)
Sr^ix—O1—W	108.2 (14)	W—O2—O3^vi	45.1 (5)
Sr^ix—O1—O3	88.1 (11)	O1—O2—O1^vi	89.4 (12)
Sr^ix—O1—O3^vi	118.3 (12)	O1—O2—O3	59.8 (10)
Sr^ix—O1—O2	66.1 (9)	O1—O2—O3^vi	59.8 (9)
Sr^ix—O1—O2^vi	147.7 (16)	O1^vi—O2—O1	89.4 (12)
Ca^x—O1—W	154.0 (15)	O1^vi—O2—O3	59.8 (9)
Ca^x—O1—O3	147.9 (12)	O1^vi—O2—O3^vi	59.9 (9)
Ca^x—O1—O3^vi	114.6 (12)	O3—O2—O3^vi	90
Ca^x—O1—O2	149.0 (13)	O3^vi—O2—O3	90

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