An Order-Disorder Theory of the Cubic-Trigonal Phase Transition in a Superionic Conductor RbAg₄I₅ Crystal

Abstract

An order-disorder theory of the first-order cubic-trigonal transition in a superionic conductor RbAg₄I₅ crystal is presented. Under a suitable choice of parameter values the fractional site occupancy by silver ions could be reasonably reproduced. The temperature dependence of an elastic stiffness constant c₄₄ is discussed.