Rerefinement of the crystal structure of SnTe_0.73(2)Se_0.27(2) from single-crystal X-ray diffraction data

Compounds of the solid solution series SnTe_1–xSe_x, derived from pristine SnSe and SnTe, are considered as thermoelectric lead-free materials. The crystal structure re-refinement of NaCl-type SnTe_0.73 (2)Se_0.27 (2) is based on single-crystal X-ray diffraction data and results in higher precision of the bond length [Sn—(Te,Se) = 3.0798 (3) Å] compared to a previous report on basis of powder X-ray data [Krebs & Langner (1964). Z. Anorg. Allg. Chem. 334, 37–49].

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma]() = 0.000 Å
• Disorder in main residue
• R factor = 0.045
• wR factor = 0.115
• Data-to-parameter ratio = 8.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT021_ALERT_4_B Ratio Unique / Expected Reflections too High ...      1.065
PLAT973_ALERT_2_B Check Calcd Positive Resid. Density on        Sn       1.59 eA-3

Alert level C
PLAT077_ALERT_4_C Unitcell Contains Non-integer Number of Atoms ..     Please Check
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       8.25 Note
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1 Note
              Se1.08 Sn4 Te2.92
PLAT971_ALERT_2_C Check Calcd Resid. Dens.  1.21A   From Te              1.73 eA-3
PLAT971_ALERT_2_C Check Calcd Resid. Dens.  0.00A   From Te              1.58 eA-3

Alert level G
PLAT004_ALERT_5_G Polymeric Structure Found with Maximum Dimension          2 Info
PLAT045_ALERT_1_G Calculated and Reported Z Differ by a Factor ...            Check
PLAT068_ALERT_1_G Reported F000 Differs from Calcd (or Missing)...     Please Check
PLAT171_ALERT_4_G The CIF-Embedded .res File Contains EADP Records          1 Report
PLAT301_ALERT_3_G Main Residue  Disorder ..............(Resd  1  )        97% Note
PLAT811_ALERT_5_G No ADDSYM Analysis: Too Many Excluded Atoms ....          ! Info
PLAT961_ALERT_5_G Dataset Contains no Negative Intensities .......     Please Check

   0 ALERT level A = Most likely a serious problem - resolve or explain
   2 ALERT level B = A potentially serious problem, consider carefully
   5 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   7 ALERT level G = General information/check it is not something unexpected

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   4 ALERT type 4 Improvement, methodology, query or suggestion
   3 ALERT type 5 Informative message, check

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Computing details

Data collection: Collect (Bruker, 1997-2004); cell refinement: DIRAX/LSQ (Duisenberg et al., 2003); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: olex2.solve (Bourhis et al., 2015); program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: publCIF (Westrip, 2010).

Tin tellurium selenide

Crystal data

SnTe0.73Se0.27	Mo Kα radiation, λ = 0.71073 Å
Mr = 233.28	Cell parameters from 553 reflections
Cubic, Fm3m	θ = 5.7–39.8°
a = 6.1595 (5) Å	µ = 23.61 mm^−1
V = 233.69 (6) Å^3	T = 150 K
Z = 4	Octahedron, black
F(000) = 389	0.10 × 0.08 × 0.07 mm
Dx = 6.631 Mg m^−3

Data collection

Nonius KappaCCD diffractometer	33 independent reflections
Radiation source: Enraf Nonius FR590	33 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
Detector resolution: 9 pixels mm^-1	θmax = 30.0°, θmin = 5.7°
CCD rotation images, thin slices scans	h = −8→8
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	k = −7→8
Tmin = 0.103, Tmax = 0.205	l = −6→8
396 measured reflections

Refinement

Refinement on F^2	4 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.045	w = 1/[σ^2(Fo^2) + (0.0583P)^2 + 1.8772P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.115	(Δ/σ)max < 0.001
S = 1.49	Δρmax = 1.92 e Å^−3
33 reflections	Δρmin = −1.84 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sn	0.000000	0.000000	0.000000	0.0199 (10)
Te	0.000000	0.000000	0.500000	0.0330 (12)	0.73 (2)
Se	0.000000	0.000000	0.500000	0.0330 (12)	0.27 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sn	0.0199 (10)	0.0199 (10)	0.0199 (10)	0.000	0.000	0.000
Te	0.0330 (12)	0.0330 (12)	0.0330 (12)	0.000	0.000	0.000
Se	0.0330 (12)	0.0330 (12)	0.0330 (12)	0.000	0.000	0.000

Geometric parameters (Å, º)

Sn—Te^i	3.0798 (3)	Sn—Te^iii	3.0798 (3)
Sn—Te	3.0798 (3)	Sn—Te^iv	3.0798 (3)
Sn—Te^ii	3.0798 (3)	Sn—Te^v	3.0798 (3)
Te^i—Sn—Te	90.0	Sn^vi—Te—Sn	90.0
Te^i—Sn—Te^ii	90.0	Sn^vi—Te—Sn^vii	90.0
Te—Sn—Te^ii	180.0	Sn—Te—Sn^vii	180.0
Te^i—Sn—Te^iii	90.0	Sn^vi—Te—Sn^viii	90.0
Te—Sn—Te^iii	90.0	Sn—Te—Sn^viii	90.0
Te^ii—Sn—Te^iii	90.0	Sn^vii—Te—Sn^viii	90.0
Te^i—Sn—Te^iv	90.0	Sn^vi—Te—Sn^ix	90.0
Te—Sn—Te^iv	90.0	Sn—Te—Sn^ix	90.0
Te^ii—Sn—Te^iv	90.0	Sn^vii—Te—Sn^ix	90.0
Te^iii—Sn—Te^iv	180.0	Sn^viii—Te—Sn^ix	180.0
Te^i—Sn—Te^v	180.0	Sn^vi—Te—Sn^x	180.0
Te—Sn—Te^v	90.0	Sn—Te—Sn^x	90.0
Te^ii—Sn—Te^v	90.0	Sn^vii—Te—Sn^x	90.0
Te^iii—Sn—Te^v	90.0	Sn^viii—Te—Sn^x	90.0
Te^iv—Sn—Te^v	90.0	Sn^ix—Te—Sn^x	90.0

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