Synthesis and Crystal Structures of Li2CuZrO4 Polymorphs

• Published in: Journal of solid state chemistry 2002-07, Vol.166 (2), p.311-319
• Main Authors: Dussarrat, Christian, Mather, Glenn C., Caignaert, Vincent, Domengès, Bernadette, Fletcher, James G., West, Anthony R.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Exact sciences and technology; Inorganic compounds; Physics; Salts; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.2002.9593

Two polymorphs of Li2CuZrO4 have been synthesized and their structures characterized by X-ray, neutron and electron diffraction. Both have novel types of ordered rock salt structure. β-Li2CuZrO4 is tetragonal, a=4.165(1) Å, c=9.418(1) Å, I-4m2, Z=4, RI=5.9%; the four sets of octahedral sites contain Zr, Li and partially ordered Li/Cu (two sets). γ-Li2CuZrO4 is orthorhombic, a=9.383(1) Å, b=5.894(1) Å, c=5.862(1) Å, Cccm, Z=8, RI=6.3%: in this case, the four sets of octahedral cation sites are fully ordered. Both structures show Jahn–Teller cooperative elongation of CuO6 octahedra. The transition from the low-temperature γ polymorph to the high-temperature β phase is first order as indicated by the presence of a transition enthalpy at an onset temperature of 1047°C on heating.