High-temperature X-ray and neutron diffraction studies of lithium metazirconate

The structure of the solid lithium-conducting electrolyte Li2ZrO3 was studied using X-ray and neutron diffraction in the range of 25 - 550 Deg C in detail. Anisotropic expansion of the lattice resulting from the changing interatomic distances in the Li2ZrO3 monoclinic structure was shown to be at rising temperature. The local oxygen surrounding about the Li(1) atom, to a lesser degree - about the Li(2) and Zr atoms suffers maximum distortion. This process is followed by the significant change in filling of the Li(1) and Li(2) positions. Anisotropy of the thermal coefficients of expansion is accompanied by the sudden change in the electric properties: jump increasing electric conductivity and decreasing activation energy (from 98.4 to 13.8 kJ/mol) are observed at 430 Deg C, connecting apparently with changing electro transport mechanism. Such changing properties may be viewed as a secondary phase transformation