Mechanism of structural phase transitions in the Li4GeO4-ZnGeO4 system: Computer modeling and identification of invariant nanocluster structures in Li4GeO4, LISICON Li6Zn(GeO4)2, and Li4Zn2(GeO4)2 (γ phase)

Abstract

The cluster modeling of structural phase transitions Li 4 GeO 4 → LISICON Li 6 Zn(GeO 4 ) 2 → γ Li 4 Zn 2 (GeO 4 ) 2 was carried out using computer assisted methods (the TOPOS program package). The pre cursor nanoclusters of crystal structures were recognized in an automated data processing mode using an algorithm developed for selecting combinations from nonintersecting suprapolyhedral clusters. 3D macro structure modeling employed the principle of maximal space filling and, accordingly, took into account the requirement for the maximal complementary connectivity of precursor nanoclusters in crystal structure self assembly followed by consecutive primary chain-microlayer-microframework assembly. A crystallochemi cally correct structure model was advanced for superionic LISICON Li 6 Zn(GeO 4 ) 2 as a 2D analogue of Li 4 GeO 4 containing only two types of voids in a layer, which are most likely to be sites for Li atoms to reside. A migration map was constructed to characterize the 2D set of conductivity channels in superionic LISICON.