Tentative model for the incommensurate and ferroelectric phases in Pb ₂ CoWO ₆

Abstract

Abstract The sequence of cubic, incommensurate and ferroelectric phases found in Pb2 CoWO6 is described in the framework of the Landau theory. The model, which involves two different order-parameters, accounts for the first-order character of the transitions, the reentrant behaviour of the incommensurate phase and its coexistence with the ferroelectric phase.