Synthesis and crystal structure of CuZrTiO5: a new inorganic
compound
Ulrike Troitzsch1, Andrew G. Christy1, David J. Ellis1 and Anthony C. Willis2
1 Research School of Earth Sciences, Australian
National University, Canberra, ACT 0200, Australia
2 Research School of Chemistry, Australian National University, Canberra,
ACT 0200, Australia
Figure 1
A new inorganic compound, CuZrTiO5, was discovered as a by-product of high-PT experiments with rutile [TiO2] and baddeleyite [ZrO2] that were fluxed with CuO. The compound was synthesized in pure form by sintering from the oxides at 1000°C under atmospheric pressure. It is bright green (Figure 1) and strongly pleochroic.
Its composition was confirmed with energy-dispersive x-ray analysis in the scanning electron microscope, and its crystal structure investigated with single-crystal and powder X-ray diffraction.
CuZrTiO5 is orthorhombic, and crystallizes in space group P212121, with unit cell dimensions a = 3.5871(3) Å, b = 6.6968(4) Å, c = 14.6679(9) Å, cell volume V = 352.35(4) Å, Z = 4, based on a single crystal refinement resulting in R = 0.032 and Rw = 0.079.
The crystal structure is topologically similar to that of In2TiO5 (Pnma) (Gaedwang et al.1993) but differs in space group and cation coordination (Figure 2). In CuZrTiO5, the two types of In are replaced by Cu and Zr. While CuZrTiO5 has relatively regular TiO6 polyhedra (Ti-O = 1.84 - 2.18 Å), Zr is in 7+1 coordination (6 O at 2.10 - 2.27 Å and one at 2.811 Å) and Cu shows the 4+2 coordination characteristic of the Jahn-Teller effect. Four O surround Cu in an approximate square at 1.915 - 2.029 Å, while two more distant neighbours lie on opposite sides of the square at 2.565 and 2.591 Å.
In CuZrTiO5, the cations are ordered into layers parallel to (001) of either pure Cu or alternating zigzag chains of Ti and Zr. This layered structure causes the distinct {001} cleavage of CuZrTiO5 observed in the electron microscope (Figure 3).
Figure 3
Figure 2
Gaewdang T, Chaminade JP, Gravereau P, Garcia A, Fouassier C, Hagenmuller P, Mahiou R (1993) Crystal structure and luminescent properties of indium titanate. Materials Research Bulletin 28:1051-1060.