Discandium(III) titanate(IV), Sc2TiO5, prepared by the flux method, has a pseudobrookite-type structure. The Sc and Ti atoms are partially disordered on the two octahedrally coordinated metal (M) sites (Wyckoff designations 8f and 4c in space group Cmcm). The most probable cation distribution suggests the approximate structural formula [8f](Sc0.6,Ti0.4)2[4c](Sc0.8Ti0.2)O5, in agreement with earlier observations of a preference of Ti for the more distorted 8f site in isotypic AIII2BIVO5 compounds. The average M-O bond lengths for the 8f and 4c sites are 2.059 and 2.095 Å, respectively. The strongly distorted octahedra share edges to form trioctahedral units, which are linked into infinite double chains along c. Further sharing of octahedral edges results in a three-dimensional framework. All atoms are on special positions. An Al-bearing variety of Sc2TiO5 has Al preferentially incorporated on the 4c site.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (Please check) = 0.000 Å
- R factor = 0.016
- wR factor = 0.048
- Data-to-parameter ratio = 15.5
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Data collection: COLLECT (Nonius, 2002); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Shape Software, 1999) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
discandium(III) titanate(IV)
top
Crystal data top
Sc2TiO5 | F(000) = 416 |
Mr = 217.82 | Dx = 3.605 Mg m−3 |
Orthorhombic, Cmcm | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2c 2 | Cell parameters from 454 reflections |
a = 3.851 (1) Å | θ = 2.0–32.6° |
b = 10.131 (2) Å | µ = 5.13 mm−1 |
c = 10.287 (2) Å | T = 293 K |
V = 401.34 (15) Å3 | Plate, colorless |
Z = 4 | 0.10 × 0.10 × 0.03 mm |
Data collection top
Nonius KappaCCD diffractometer | 435 independent reflections |
Radiation source: fine-focus sealed tube | 416 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.008 |
φ and ω scans | θmax = 32.5°, θmin = 4.0° |
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski & Minor, 1997) | h = −5→5 |
Tmin = 0.628, Tmax = 0.883 | k = −15→15 |
728 measured reflections | l = −15→15 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.016 | w = 1/[σ2(Fo2) + (0.02P)2 + 0.83P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.048 | (Δ/σ)max < 0.001 |
S = 1.20 | Δρmax = 0.85 e Å−3 |
435 reflections | Δρmin = −0.85 e Å−3 |
28 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0143 (12) |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ti1 | 0.0000 | 0.36444 (3) | 0.43775 (3) | 0.00474 (12) | 0.40 |
Sc1 | 0.0000 | 0.36444 (3) | 0.43775 (3) | 0.00474 (12) | 0.60 |
Ti2 | 0.0000 | 0.30752 (4) | 0.7500 | 0.00549 (13) | 0.20 |
Sc2 | 0.0000 | 0.30752 (4) | 0.7500 | 0.00549 (13) | 0.80 |
O1 | 0.0000 | 0.45339 (14) | 0.61424 (15) | 0.0146 (3) | |
O2 | −0.5000 | 0.23222 (19) | 0.7500 | 0.0088 (3) | |
O3 | 0.0000 | 0.19241 (13) | 0.57087 (13) | 0.0096 (3) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ti1 | 0.00496 (17) | 0.00393 (17) | 0.00533 (17) | 0.000 | 0.000 | −0.00004 (9) |
Sc1 | 0.00496 (17) | 0.00393 (17) | 0.00533 (17) | 0.000 | 0.000 | −0.00004 (9) |
Ti2 | 0.0059 (2) | 0.0061 (2) | 0.0044 (2) | 0.000 | 0.000 | 0.000 |
Sc2 | 0.0059 (2) | 0.0061 (2) | 0.0044 (2) | 0.000 | 0.000 | 0.000 |
O1 | 0.0159 (7) | 0.0184 (7) | 0.0095 (6) | 0.000 | 0.000 | 0.0059 (5) |
O2 | 0.0078 (8) | 0.0112 (8) | 0.0075 (7) | 0.000 | 0.000 | 0.000 |
O3 | 0.0114 (6) | 0.0092 (6) | 0.0082 (6) | 0.000 | 0.000 | −0.0002 (4) |
Geometric parameters (Å, º) top
Ti1—O1i | 1.9215 (15) | Sc2—O1iv | 2.0333 (14) |
Ti1—O3ii | 2.0117 (6) | Sc2—O1 | 2.0333 (14) |
Ti1—O3iii | 2.0117 (6) | Sc2—O2 | 2.0711 (9) |
Ti1—O1 | 2.0269 (16) | Sc2—O2v | 2.0711 (9) |
Ti1—O2ii | 2.1655 (10) | Sc2—O3 | 2.1807 (14) |
Ti1—O3 | 2.2164 (14) | Sc2—O3iv | 2.1807 (14) |
| | | |
O1i—Ti1—O3ii | 105.23 (4) | Ti1i—O1—Ti2 | 152.78 (9) |
O1i—Ti1—O3iii | 105.23 (4) | Ti1—O1—Ti2 | 106.98 (7) |
O3ii—Ti1—O3iii | 146.32 (8) | Ti2—O2—Sc2vi | 136.78 (10) |
O1i—Ti1—O1 | 79.76 (7) | Ti2—O2—Ti2vi | 136.78 (10) |
O3ii—Ti1—O1 | 99.60 (4) | Ti2—O2—Ti1ii | 99.588 (9) |
O3iii—Ti1—O1 | 99.60 (4) | Sc2vi—O2—Ti1ii | 99.588 (9) |
O1i—Ti1—O2ii | 100.73 (7) | Ti2vi—O2—Ti1ii | 99.588 (9) |
O3ii—Ti1—O2ii | 80.28 (4) | Ti2—O2—Sc1ii | 99.588 (9) |
O3iii—Ti1—O2ii | 80.28 (4) | Sc2vi—O2—Sc1ii | 99.588 (9) |
O1—Ti1—O2ii | 179.51 (6) | Ti2vi—O2—Sc1ii | 99.588 (9) |
O1i—Ti1—O3 | 158.00 (6) | Ti2—O2—Sc1vii | 99.588 (9) |
O3ii—Ti1—O3 | 78.59 (4) | Sc2vi—O2—Sc1vii | 99.588 (9) |
O3iii—Ti1—O3 | 78.59 (4) | Ti2vi—O2—Sc1vii | 99.588 (9) |
O1—Ti1—O3 | 78.24 (5) | Ti1ii—O2—Sc1vii | 126.23 (9) |
O2ii—Ti1—O3 | 101.27 (6) | Sc1ii—O2—Sc1vii | 126.23 (9) |
O1iv—Ti2—O1 | 86.76 (9) | Ti2—O2—Ti1vii | 99.588 (9) |
O1iv—Ti2—O2 | 105.53 (4) | Sc2vi—O2—Ti1vii | 99.588 (9) |
O1—Ti2—O2 | 105.53 (4) | Ti2vi—O2—Ti1vii | 99.588 (9) |
O1iv—Ti2—O2v | 105.53 (4) | Ti1ii—O2—Ti1vii | 126.23 (9) |
O1—Ti2—O2v | 105.53 (4) | Sc1ii—O2—Ti1vii | 126.23 (9) |
O2—Ti2—O2v | 136.78 (10) | Sc1ii—O3—Sc1iii | 146.32 (8) |
O1iv—Ti2—O3 | 165.71 (6) | Ti1ii—O3—Sc1iii | 146.32 (8) |
O1—Ti2—O3 | 78.95 (6) | Sc1ii—O3—Ti1iii | 146.32 (8) |
O2—Ti2—O3 | 78.64 (3) | Ti1ii—O3—Ti1iii | 146.32 (8) |
O2v—Ti2—O3 | 78.64 (3) | Sc1ii—O3—Ti2 | 100.97 (4) |
O1iv—Ti2—O3iv | 78.95 (6) | Ti1ii—O3—Ti2 | 100.97 (4) |
O1—Ti2—O3iv | 165.71 (6) | Sc1iii—O3—Ti2 | 100.97 (4) |
O2—Ti2—O3iv | 78.64 (3) | Ti1iii—O3—Ti2 | 100.97 (4) |
O2v—Ti2—O3iv | 78.64 (3) | Sc1ii—O3—Ti1 | 101.41 (4) |
O3—Ti2—O3iv | 115.35 (8) | Ti1ii—O3—Ti1 | 101.41 (4) |
Sc1i—O1—Ti1 | 100.24 (7) | Sc1iii—O3—Ti1 | 101.41 (4) |
Ti1i—O1—Ti1 | 100.24 (7) | Ti1iii—O3—Ti1 | 101.41 (4) |
Sc1i—O1—Ti2 | 152.78 (9) | Ti2—O3—Ti1 | 95.83 (6) |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) −x−1/2, −y+1/2, −z+1; (iii) −x+1/2, −y+1/2, −z+1; (iv) x, y, −z+3/2; (v) x+1, y, z; (vi) x−1, y, z; (vii) −x−1/2, −y+1/2, z+1/2. |