Acta Cryst. (2003). E59, i36-i39  [ doi:10.1107/S1600536803003544 ]

Sc₂TiO₅, an entropy-stabilized pseudobrookite-type compound

U. Kolitsch and E. Tillmanns

Abstract: 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](Sc_0.6,Ti_0.4)₂^[4c](Sc_0.8Ti_0.2)O₅, in agreement with earlier observations of a preference of Ti for the more distorted 8f site in isotypic A^III₂B^IVO₅ 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.

Online 21 February 2003

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