Synthesis and crystal structure of CuZrTiO5-A new crystal structure type

A new compound, CuZrTiO5, was synthesized as strongly pleochroic green crystals from the oxides between 995 and 1010 deg. C, 1 atm. Its crystal structure was determined by single crystal XRD, resulting in R (F2>2σ(F2))=0.032 and wR (all data)=0.079). CuZrTiO5 is orthorhombic, space group P212121, a=3.5871(3) A, b=6.6968(4) A, c=14.6679(9) A, V=352.35(4) A3, Z=4. The structure is topologically similar to In2TiO5 but differs in space group and cation coordination. CuZrTiO5 has relatively regular TiO6 polyhedra, but coordination is 7+1 for Zr, and 4+2 for Cu due to the Jahn-Teller effect. Ordering of the long Cu-O bonds causes reduction in symmetry relative to In2TiO5. Layers of Cu alternate with Ti+Zr on (001), giving rise to a distinct cleavage. Bond valence sums on Ti and Zr are far from ideal, which appears due to the limited ability of this structural topology to avoid close next-nearest neighbour distances. - Graphical abstract: The new compound CuZrTiO5 is orthorhombic (P212121), with a=3.5871(3) A, b=6.6968(4) A, c=14.6679(9) A. The structure, determined with single crystal XRD, represents a new crystal structure type that is a slight distortion of that of In2TiO5 but differs in space group and cation coordination.