Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805041747/wm6121sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536805041747/wm6121Isup2.hkl |
Sc2Te3 was obtained from a reaction of elemental scandium, nickel and tellurium in the ratio 1:4:7. The mixture was heated at 1073 K over a period of 3 d, annealed at 923 K for 5 d, and then cooled slowly (5 K h−1) to room temperature. The X-ray diagram obtained from the ground sample (utilizing the INEL powder diffractometer with position-sensitive detector) revealed the presence of Sc2Te3, NiTe and NiTe2. Sc2Te3 crystallized in the form of black block-shaped crystals.
Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: coordinates taken from the isotypic Sc2S3 compound (Dismukes & White, 1964); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1999); software used to prepare material for publication: SHELXL97.
Fig. 1. The crystal structure of Sc2Te3, with anisotropic displacement ellipsoids drawn at the 90% probability level. |
Sc2Te3 | F(000) = 3168 |
Mr = 472.72 | Dx = 5.338 Mg m−3 |
Orthorhombic, Fddd | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -F 2uv 2vw | Cell parameters from 4570 reflections |
a = 8.2223 (6) Å | θ = 3.2–30.0° |
b = 11.6292 (9) Å | µ = 16.73 mm−1 |
c = 24.6085 (18) Å | T = 298 K |
V = 2353.0 (3) Å3 | Block, black |
Z = 16 | 0.02 × 0.02 × 0.01 mm |
Bruker SMART APEX CCD diffractometer | 858 independent reflections |
Radiation source: fine-focus sealed tube | 672 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
ϕ and ω scans | θmax = 30.0°, θmin = 3.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −11→11 |
Tmin = 0.70, Tmax = 0.90 | k = −16→16 |
4570 measured reflections | l = −34→33 |
Refinement on F2 | Primary atom site location: isomorphous structure methods |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0244P)2] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.031 | (Δ/σ)max = 0.001 |
wR(F2) = 0.089 | Δρmax = 1.27 e Å−3 |
S = 1.41 | Δρmin = −2.84 e Å−3 |
858 reflections | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
26 parameters | Extinction coefficient: 0.00165 (5) |
0 restraints |
Sc2Te3 | V = 2353.0 (3) Å3 |
Mr = 472.72 | Z = 16 |
Orthorhombic, Fddd | Mo Kα radiation |
a = 8.2223 (6) Å | µ = 16.73 mm−1 |
b = 11.6292 (9) Å | T = 298 K |
c = 24.6085 (18) Å | 0.02 × 0.02 × 0.01 mm |
Bruker SMART APEX CCD diffractometer | 858 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 672 reflections with I > 2σ(I) |
Tmin = 0.70, Tmax = 0.90 | Rint = 0.030 |
4570 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 26 parameters |
wR(F2) = 0.089 | 0 restraints |
S = 1.41 | Δρmax = 1.27 e Å−3 |
858 reflections | Δρmin = −2.84 e Å−3 |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Sc1 | 0.1250 | 0.1250 | 0.042989 (19) | 0.0096 (2) | |
Sc2 | 0.1250 | 0.1250 | 0.37467 (2) | 0.0094 (2) | |
Te1 | 0.37907 (2) | 0.1250 | 0.1250 | 0.00811 (19) | |
Te2 | 0.375092 (12) | 0.125142 (10) | 0.458253 (4) | 0.00822 (19) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sc1 | 0.0099 (4) | 0.0095 (3) | 0.0095 (3) | −0.0004 (2) | 0.000 | 0.000 |
Sc2 | 0.0093 (3) | 0.0085 (3) | 0.0103 (3) | 0.00058 (16) | 0.000 | 0.000 |
Te1 | 0.0087 (3) | 0.0062 (3) | 0.0094 (3) | 0.000 | 0.000 | 0.00004 (5) |
Te2 | 0.0077 (3) | 0.0096 (3) | 0.0073 (3) | −0.00037 (11) | −0.00146 (4) | −0.00027 (4) |
Sc1—Te1 | 2.9047 (4) | Sc2—Te1ii | 2.9075 (2) |
Sc1—Te1i | 2.9047 (4) | Sc2—Te2 | 2.9084 (4) |
Sc1—Te2ii | 2.9091 (3) | Sc2—Te2i | 2.9084 (4) |
Sc1—Te2iii | 2.9091 (2) | Te1—Sc1viii | 2.9047 (4) |
Sc1—Te2iv | 2.9275 (4) | Te1—Sc2ix | 2.9075 (2) |
Sc1—Te2v | 2.9275 (4) | Te1—Sc2iii | 2.9075 (2) |
Sc2—Te2vi | 2.8960 (4) | Te2—Sc2vii | 2.8960 (4) |
Sc2—Te2vii | 2.8960 (4) | Te2—Sc1iii | 2.9091 (2) |
Sc2—Te1iii | 2.9075 (2) | Te2—Sc1x | 2.9275 (4) |
Te1—Sc1—Te1i | 91.978 (15) | Te2vi—Sc2—Te2 | 179.797 (14) |
Te1—Sc1—Te2ii | 90.408 (7) | Te2vii—Sc2—Te2 | 89.808 (6) |
Te1i—Sc1—Te2ii | 90.429 (7) | Te1iii—Sc2—Te2 | 90.388 (8) |
Te1—Sc1—Te2iii | 90.429 (7) | Te1ii—Sc2—Te2 | 89.389 (8) |
Te1i—Sc1—Te2iii | 90.408 (7) | Te2vi—Sc2—Te2i | 89.809 (7) |
Te2ii—Sc1—Te2iii | 178.796 (19) | Te2vii—Sc2—Te2i | 179.797 (14) |
Te1—Sc1—Te2iv | 178.590 (13) | Te1iii—Sc2—Te2i | 89.389 (8) |
Te1i—Sc1—Te2iv | 89.432 (7) | Te1ii—Sc2—Te2i | 90.387 (8) |
Te2ii—Sc1—Te2iv | 89.549 (7) | Te2—Sc2—Te2i | 89.988 (15) |
Te2iii—Sc1—Te2iv | 89.593 (7) | Sc1—Te1—Sc1viii | 88.022 (15) |
Te1—Sc1—Te2v | 89.432 (7) | Sc1—Te1—Sc2ix | 89.415 (7) |
Te1i—Sc1—Te2v | 178.590 (13) | Sc1viii—Te1—Sc2ix | 89.635 (7) |
Te2ii—Sc1—Te2v | 89.593 (7) | Sc1—Te1—Sc2iii | 89.635 (7) |
Te2iii—Sc1—Te2v | 89.549 (7) | Sc1viii—Te1—Sc2iii | 89.415 (7) |
Te2iv—Sc1—Te2v | 89.158 (14) | Sc2ix—Te1—Sc2iii | 178.680 (8) |
Te2vi—Sc2—Te2vii | 90.395 (15) | Sc2vii—Te2—Sc2 | 90.191 (6) |
Te2vi—Sc2—Te1iii | 89.610 (7) | Sc2vii—Te2—Sc1iii | 89.554 (7) |
Te2vii—Sc2—Te1iii | 90.612 (8) | Sc2—Te2—Sc1iii | 89.531 (7) |
Te2vi—Sc2—Te1ii | 90.612 (8) | Sc2vii—Te2—Sc1x | 90.224 (11) |
Te2vii—Sc2—Te1ii | 89.610 (7) | Sc2—Te2—Sc1x | 179.580 (10) |
Te1iii—Sc2—Te1ii | 179.684 (19) | Sc1iii—Te2—Sc1x | 90.407 (7) |
Symmetry codes: (i) −x+1/4, −y+1/4, z; (ii) x−1/4, y+1/4, −z+1/2; (iii) −x+1/2, −y, −z+1/2; (iv) x−1/2, y, z−1/2; (v) −x+3/4, −y+1/4, z−1/2; (vi) x−1/2, −y+1/4, −z+3/4; (vii) −x+3/4, y, −z+3/4; (viii) −x+1/4, y, −z+1/4; (ix) x+1/4, −y+1/2, z−1/4; (x) x+1/2, y, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | Sc2Te3 |
Mr | 472.72 |
Crystal system, space group | Orthorhombic, Fddd |
Temperature (K) | 298 |
a, b, c (Å) | 8.2223 (6), 11.6292 (9), 24.6085 (18) |
V (Å3) | 2353.0 (3) |
Z | 16 |
Radiation type | Mo Kα |
µ (mm−1) | 16.73 |
Crystal size (mm) | 0.02 × 0.02 × 0.01 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.70, 0.90 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4570, 858, 672 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.089, 1.41 |
No. of reflections | 858 |
No. of parameters | 26 |
Δρmax, Δρmin (e Å−3) | 1.27, −2.84 |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 1999), SAINT, coordinates taken from the isotypic Sc2S3 compound (Dismukes & White, 1964), SHELXL97 (Sheldrick, 1997), DIAMOND (Bergerhoff, 1999), SHELXL97.
Sc1—Te1 | 2.9047 (4) | Sc2—Te2iii | 2.8960 (4) |
Sc1—Te2i | 2.9091 (2) | Sc2—Te1i | 2.9075 (2) |
Sc1—Te2ii | 2.9275 (4) | Sc2—Te2 | 2.9084 (4) |
Symmetry codes: (i) −x+1/2, −y, −z+1/2; (ii) −x+3/4, −y+1/4, z−1/2; (iii) −x+3/4, y, −z+3/4. |
Recently, we reported the crystal structure of Yb2Se3, which crystallizes in the Sc2S3 structure type (Assoud & Kleinke, 2003). The chalcogenides Ln2Q3 (Ln = lanthanide, Q = chalcogen) adopt different structure types depending on the radius of the lanthanide. The large lanthanide chalcogenides prefer the defect variant of the Th3P4 type (Mauricot et al., 1995), whereas the smaller ones crystallize in the α-Al2O3 (El Fadli et al., 1994) and Sc2S3 types (Dismukes & White, 1965; Flahaut et al., 1965).
In the system Sc–Te, several binaries ave been synthesized and their crystal structures characterized, viz. ScTe, Sc2/3Te (Men'kov et al., 1961), Sc2Te3, Sc2.3Te3 (White & Dismukes, 1965), Sc2Te (Maggard & Corbett, 1997), Sc9Te2 (Maggard & Corbett, 2000) and Sc8Te3 (Maggard & Corbett, 1998). The first modification of Sc2Te3 was reported, on the basis of X-ray powder diffraction data (Men'kov et al., 1959), to exhibit the γ-Al2O3 structure type. The second, rhombohedral modification was found by reacting the mixture of elements at the same reaction temperature (1325 K) but using chemical transport reactions. This modification was described as comprising alternating regions of NaCl and NiAs structure types (White & Dismukes, 1965).
Our single-crystal structure study on Sc2Te3 shows a third modification, which adopts the Sc2S3 type (Dismukes & White, 1964). This seems to be the low-temperature form, as we have routinely observed it at reaction temperatures below 1100 K, regardless of whether nickel was present in the reaction mixture or not. This structure is a distorted deficient variant of the NaCl type, forming a 12-fold supercell (a = 21/2a, b = 2b, c = 3 × 21/2c). A detailed description of the Sc2S3 type and its relation to NaCl was given by Dismukes & White (1964). The distortion can be seen in, for example, the shifts of the Te atoms from the ideal position with x = 0.375 to x = 0.37907 (2) (Te1) and x = 0.375092 (12) (Te2). The Sc—Te bond lengths scatter slightly around 2.91 Å (Table 1), and the Te—Sc—Te angles deviate up to 2° from the ideal octahedral angles.