Tetragonal SmBa₂Cu₃O_7-x [x = 0.74 (4)]

Crystals of the title compound, samarium barium copper oxide, were prepared by a modified top-seeded solution-growth method. The crystals thus prepared showed no superconductivity down to 4.2 K. A careful examination showed that the structure closely resembles that of tetragonal YBCO, and there is no atom mixing at the Ba or other sites, within experimental accuracy. A bond-valence-sum calculation at the Ba site also indicated the absence of Sm. Each site is fully occupied by a single atom, except for the oxy­gen site in the basal plane of the CuO₆ octahedron. The occupancy of this oxy­gen site is significantly reduced [0.13 (2)], as is commonly observed in the 123 system. The atomic displacement parameters of the atoms in the CuO₂ plane, as well as of the Sm atom, are very small, indicating that two equivalent CuO₂ planes tightly sandwich the Sm atom.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1998); program(s) used to solve structure: SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

(I)

Crystal data

SmBa2Cu3O6.26	Dx = 6.69 Mg m^−3
Mr = 715.85	Mo Kα radiation, λ = 0.7107 Å
Tetragonal, P4/mmm	Cell parameters from 25 reflections
Hall symbol: -P 4 2	θ = 26.1–28.5°
a = 3.878 (1) Å	µ = 27.83 mm^−1
c = 11.818 (2) Å	T = 297 K
V = 177.76 (6) Å^3	Plate, black
Z = 1	0.50 × 0.33 × 0.12 mm

Data collection

Rigaku AFC-5R diffractometer	Rint = 0.030
ω/2θ scans	θmax = 50.2°
Absorption correction: analytical (de Meulenaer & Tompa, 1965)	h = 0→8
Tmin = 0.006, Tmax = 0.122	k = 0→8
1148 measured reflections	l = 0→25
641 independent reflections	4 standard reflections every 150 reflections
533 reflections with F^2 > 2σ(F^2)	intensity decay: 0.4%

Refinement

Refinement on F	w = 1/[σ^2(Fo) + 0.00006|Fo|^2]
R[F^2 > 2σ(F^2)] = 0.019	(Δ/σ)max < 0.001
wR(F^2) = 0.026	Δρmax = 2.83 e Å^−3
S = 1.59	Δρmin = −1.93 e Å^−3
533 reflections	Extinction correction: Zachariasen (1967) type 2 Gaussian isotropic
21 parameters	Extinction coefficient: 1.59 (7)

Special details

Refinement. Refinement using reflections with F² > 2.0 σ(F²). The weighted R-factor (wR), goodness of fit (S) and R-factor (gt) are based on F. The numbers of reflections used for ls and gt are the same.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sm	1/2	1/2	1/2	0.00430 (3)
Ba	1/2	1/2	0.19249 (2)	0.00792 (3)
Cu1	0	0	0	0.01057 (8)
Cu2	0	0	0.35607 (5)	0.00497 (5)
O1	0	0	0.1531 (3)	0.0152 (3)
O2	0	1/2	0	0.016 (7)*	0.13 (2)
O3	0	1/2	0.3735 (2)	0.0073 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sm	0.00349 (7)	0.00349	0.0059 (1)	0	0	0
Ba	0.00783 (7)	0.00783	0.0081 (1)	0	0	0
Cu1	0.0124 (2)	0.0124	0.0069 (3)	0	0	0
Cu2	0.00292 (9)	0.00292	0.0091 (2)	0	0	0
O1	0.018 (1)	0.0184	0.009 (1)	0	0	0
O3	0.0061 (6)	0.0035 (5)	0.0122 (7)	0	0	0

Geometric parameters (Å, º)

Sm—Cu2	3.2271 (4)	Cu1—O1	1.810 (4)
Sm—O3	2.448 (1)	Cu1—O2	1.9391 (5)
Ba—Cu2	3.3553 (5)	Cu2—Cu2^i	3.402 (1)
Ba—O1	2.7815 (7)	Cu2—O1	2.398 (4)
Ba—O2	2.9892 (4)	Cu2—O3	1.9501 (2)
Ba—O3	2.888 (2)
Sm···Cu2	3.2271 (4)	O1···O3^x	3.247 (4)
Sm···Cu2^i	3.2271 (4)	O1···O3^xi	3.247 (4)
Sm···Cu2^ii	3.2271 (4)	O1···O3^viii	3.247 (4)
Sm···Cu2^iii	3.2271 (4)	O2···O2^x	2.7424 (4)
Sm···Cu2^iv	3.2271 (4)	O2···O2^xii	2.7424 (4)
Sm···Cu2^v	3.2271 (4)	O2···O2^viii	2.7424 (4)
Sm···Cu2^vi	3.2271 (4)	O2···O2^ix	2.7424 (4)
Sm···Cu2^vii	3.2271 (4)	O3···O3^x	2.7424 (4)
Ba···Cu2	3.3553 (5)	O3···O3^xii	2.7424 (4)
Ba···Cu2^ii	3.3553 (5)	O3···O3^iii	2.990 (4)
Ba···Cu2^iv	3.3553 (5)	O3···O3^viii	2.7424 (4)
Ba···Cu2^vi	3.3553 (5)	O3···O3^ix	2.7424 (4)
Ba···O1	2.7815 (7)	Ba···O1^vi	2.7815 (7)
Ba···O1^ii	2.7815 (7)	Ba···O1^iv	2.7815 (7)
Ba···O1^iv	2.7815 (7)	Ba···O1^ii	2.7815 (7)
Ba···O1^vi	2.7815 (7)	Ba···O1	2.7815 (7)
Ba···O2	2.9892 (4)	Ba···O3^iv	2.888 (2)
Ba···O2^iv	2.9892 (4)	Ba···O3	2.888 (2)
Ba···O2^viii	2.9892 (2)	Ba···O3^ix	2.888 (2)
Ba···O2^ix	2.9892 (2)	Ba···O3^viii	2.888 (2)
Ba···O3	2.888 (2)	Ba···O2^iv	2.9892 (4)
Ba···O3^iv	2.888 (2)	Ba···O2	2.9892 (4)
Ba···O3^viii	2.888 (2)	Ba···O2^ix	2.9892 (2)
Ba···O3^ix	2.888 (2)	Ba···O2^viii	2.9892 (2)
Cu2···Cu2^i	3.402 (1)	O2···O2^ix	2.7424 (4)
O1···O2	2.653 (3)	O2···O2^xii	2.7424 (4)
O1···O2^x	2.653 (3)	O3···O3^ix	2.7424 (4)
O1···O2^xi	2.653 (3)	O3···O3^xii	2.7424 (4)
O1···O2^viii	2.653 (3)	O3···O3^iii	2.990 (4)
O1···O3	3.247 (4)
O3—Sm—O3^xiii	111.88 (4)	O2^iv—Ba—O3^viii	124.32 (2)
O3—Sm—O3^iii	75.25 (8)	O2^iv—Ba—O3^ix	124.32 (2)
O3—Sm—O3^xiv	111.88 (4)	O2^viii—Ba—O2^ix	80.891 (6)
O3—Sm—O3^iv	104.75 (8)	O2^viii—Ba—O3	124.32 (2)
O3—Sm—O3^viii	68.12 (4)	O2^viii—Ba—O3^iv	124.32 (2)
O3—Sm—O3^ix	68.12 (4)	O2^viii—Ba—O3^viii	97.37 (3)
O3—Sm—O3^vii	180.0000 (1)	O2^viii—Ba—O3^ix	178.26 (3)
O3^xiii—Sm—O3^iii	68.12 (4)	O2^ix—Ba—O3	124.32 (2)
O3^xiii—Sm—O3^xiv	104.75 (8)	O2^ix—Ba—O3^iv	124.32 (2)
O3^xiii—Sm—O3^iv	111.88 (4)	O2^ix—Ba—O3^viii	178.26 (3)
O3^xiii—Sm—O3^viii	75.25 (8)	O2^ix—Ba—O3^ix	97.37 (3)
O3^xiii—Sm—O3^ix	180.0000 (1)	O3—Ba—O3^iv	84.37 (6)
O3^xiii—Sm—O3^vii	68.12 (4)	O3—Ba—O3^viii	56.70 (4)
O3^iii—Sm—O3^xiv	68.12 (4)	O3—Ba—O3^ix	56.70 (4)
O3^iii—Sm—O3^iv	180.0000 (1)	O3^iv—Ba—O3^viii	56.70 (4)
O3^iii—Sm—O3^viii	111.88 (4)	O3^iv—Ba—O3^ix	56.70 (4)
O3^iii—Sm—O3^ix	111.88 (4)	O3^viii—Ba—O3^ix	84.37 (6)
O3^iii—Sm—O3^vii	104.75 (8)	O1—Cu1—O1^xv	180.0
O3^xiv—Sm—O3^iv	111.88 (4)	O1—Cu1—O2	90.0
O3^xiv—Sm—O3^viii	180.0000 (1)	O1—Cu1—O2^x	90.0
O3^xiv—Sm—O3^ix	75.25 (8)	O1—Cu1—O2^xi	90.0
O3^xiv—Sm—O3^vii	68.12 (4)	O1—Cu1—O2^viii	90.0
O3^iv—Sm—O3^viii	68.12 (4)	O1^xv—Cu1—O2	90.0
O3^iv—Sm—O3^ix	68.12 (4)	O1^xv—Cu1—O2^x	90.0
O3^iv—Sm—O3^vii	75.25 (8)	O1^xv—Cu1—O2^xi	90.0
O3^viii—Sm—O3^ix	104.75 (8)	O1^xv—Cu1—O2^viii	90.0
O3^viii—Sm—O3^vii	111.88 (4)	O2—Cu1—O2^x	90.0
O3^ix—Sm—O3^vii	111.88 (4)	O2—Cu1—O2^xi	180.0
O1—Ba—O1^ii	88.40 (3)	O2—Cu1—O2^viii	90.0
O1—Ba—O1^iv	88.40 (3)	O2^x—Cu1—O2^xi	90.0
O1—Ba—O1^vi	160.8 (2)	O2^x—Cu1—O2^viii	180.0
O1—Ba—O2	54.59 (6)	O2^xi—Cu1—O2^viii	90.0
O1—Ba—O2^iv	108.97 (7)	O1—Cu2—O3	96.07 (7)
O1—Ba—O2^viii	54.59 (6)	O1—Cu2—O3^x	96.07 (7)
O1—Ba—O2^ix	108.97 (7)	O1—Cu2—O3^xi	96.07 (7)
O1—Ba—O3	69.86 (7)	O1—Cu2—O3^viii	96.07 (7)
O1—Ba—O3^iv	126.30 (6)	O3—Cu2—O3^x	89.36 (1)
O1—Ba—O3^viii	69.86 (7)	O3—Cu2—O3^xi	167.9 (1)
O1—Ba—O3^ix	126.30 (6)	O3—Cu2—O3^viii	89.36 (1)
O1^ii—Ba—O1^iv	160.8 (2)	O3^x—Cu2—O3^xi	89.36 (1)
O1^ii—Ba—O1^vi	88.40 (3)	O3^x—Cu2—O3^viii	167.9 (1)
O1^ii—Ba—O2	54.59 (6)	O3^xi—Cu2—O3^viii	89.36 (1)
O1^ii—Ba—O2^iv	108.97 (7)	Ba—O1—Ba^xvi	160.8 (2)
O1^ii—Ba—O2^viii	108.97 (7)	Ba—O1—Ba^xvii	88.40 (3)
O1^ii—Ba—O2^ix	54.59 (6)	Ba—O1—Ba^xi	88.40 (3)
O1^ii—Ba—O3	69.86 (7)	Ba—O1—Cu1	99.62 (8)
O1^ii—Ba—O3^iv	126.30 (6)	Ba—O1—Cu2	80.38 (8)
O1^ii—Ba—O3^viii	126.30 (6)	Ba^xvi—O1—Ba^xvii	88.40 (3)
O1^ii—Ba—O3^ix	69.86 (7)	Ba^xvi—O1—Ba^xi	88.40 (3)
O1^iv—Ba—O1^vi	88.40 (3)	Ba^xvi—O1—Cu1	99.62 (8)
O1^iv—Ba—O2	108.97 (7)	Ba^xvi—O1—Cu2	80.38 (8)
O1^iv—Ba—O2^iv	54.59 (6)	Ba^xvii—O1—Ba^xi	160.8 (2)
O1^iv—Ba—O2^viii	54.59 (6)	Ba^xvii—O1—Cu1	99.62 (8)
O1^iv—Ba—O2^ix	108.97 (7)	Ba^xvii—O1—Cu2	80.38 (8)
O1^iv—Ba—O3	126.30 (6)	Ba^xi—O1—Cu1	99.62 (8)
O1^iv—Ba—O3^iv	69.86 (7)	Ba^xi—O1—Cu2	80.38 (8)
O1^iv—Ba—O3^viii	69.86 (7)	Cu1—O1—Cu2	180.0
O1^iv—Ba—O3^ix	126.30 (6)	Ba—O2—Ba^xvii	80.89 (2)
O1^vi—Ba—O2	108.97 (7)	Ba—O2—Ba^xviii	180.0
O1^vi—Ba—O2^iv	54.59 (6)	Ba—O2—Ba^xix	99.11 (2)
O1^vi—Ba—O2^viii	108.97 (7)	Ba—O2—Cu1	90.0
O1^vi—Ba—O2^ix	54.59 (6)	Ba—O2—Cu1^ii	90.0
O1^vi—Ba—O3	126.30 (6)	Ba^xvii—O2—Ba^xviii	99.11 (2)
O1^vi—Ba—O3^iv	69.86 (7)	Ba^xvii—O2—Ba^xix	180.0
O1^vi—Ba—O3^viii	126.30 (6)	Ba^xvii—O2—Cu1	90.0
O1^vi—Ba—O3^ix	69.86 (7)	Ba^xvii—O2—Cu1^ii	90.0
O2—Ba—O2^iv	80.89 (2)	Ba^xviii—O2—Ba^xix	80.89 (2)
O2—Ba—O2^viii	54.609 (6)	Ba^xviii—O2—Cu1	90.0
O2—Ba—O2^ix	54.609 (6)	Ba^xviii—O2—Cu1^ii	90.0
O2—Ba—O3	97.37 (3)	Ba^xix—O2—Cu1	90.0
O2—Ba—O3^iv	178.26 (3)	Ba^xix—O2—Cu1^ii	90.0
O2—Ba—O3^viii	124.32 (2)	Cu1—O2—Cu1^ii	180.0
O2—Ba—O3^ix	124.32 (2)	Sm—O3—Sm^xvii	104.75 (8)
O2^iv—Ba—O2^viii	54.609 (6)	Sm—O3—Ba	85.44 (2)
O2^iv—Ba—O2^ix	54.609 (6)	Sm—O3—Ba^xvii	169.81 (7)
O2^iv—Ba—O3	178.26 (3)	Cu2—O3—Cu2^ii	167.9 (1)
O2^iv—Ba—O3^iv	97.37 (3)

Symmetry codes: (i) −x, −y, −z+1; (ii) x, y+1, z; (iii) −x, −y+1, −z+1; (iv) x+1, y, z; (v) −x+1, −y, −z+1; (vi) x+1, y+1, z; (vii) −x+1, −y+1, −z+1; (viii) −y+1, x, z; (ix) −y+1, x+1, z; (x) −y, x, z; (xi) x, y−1, z; (xii) −y, x+1, z; (xiii) y, −x, −z+1; (xiv) y, −x+1, −z+1; (xv) −x, −y, −z; (xvi) x−1, y−1, z; (xvii) x−1, y, z; (xviii) −x, −y+1, −z; (xix) −x+1, −y+1, −z.