The natural tiling approach to cation conductivity in KAlO2 polymorphs

Abstract

A detailed analysis of correlations between structural features and cation conductivity is performed for KAlO2 polymorphs in a wide temperature range of 300–1023 K. To explore the migration maps of K+ cations we have used neutron diffraction data for low- and high-temperature KAlO2 polymorphs and applied for the first time a novel algorithm based on the natural tiling concept and implemented it into the program package TOPOS. Five independent elementary channels for the K+ cation migration have been revealed whose cross-sections were found to be essentially different in the low-temperature form, indicating a high anisotropy of the cation conductivity. During the transition to the cubic high-temperature phase all five channels become equivalent with sharply increased cross-sections that account for the jump-like increase of the cation conductivity and gives rise to its three-dimensional character.