Defect clusterization and transport properties of oxide and fluoride ionicconductors with fluorite structure: Quantum-chemical approach

Systematic studies of the effect of point defects on the electronic structu re, chemical bond, and ionic conduction of classical ionic conductors MeF2 (Me = Ca, Sr, Ba, Pb), ZrO2-CaO, ZrO2-Y2O3, and delta -Bi2O3 are carried ou t using the nonempirical LMTO method in the tight-binding approximation and using Huckel's semiempirical method. The energies of formation and interac tion of anti-Frenkel defects are calculated. The effect of defect clusteriz ation in these compounds is detected. This effect is responsible for the em ergence of the superionic state and anomalous physicochemical properties of the given solid electrolytes. The nature of instability of the fluorite st ructure is studied, and methods of its stabilization are proposed. The mech anisms and energetics of ionic transport in oxide and fluoride conductors w ith fluorite structure are investigated. (C) 2001 MAIK "Nauka/Interperiodic a".