PHASE COEXISTENCE IN PROTON GLASS

Phase coexistence results from quenched structural randomness and frus trated interactions. The nature of this randomness and the frustrated interactions in proton glass are explained. The six types of ordered d omains and corresponding ferroelectric and antiferroelectric phases ar e described, as well as the disordered paraelectric and proton glass p hases. Experimental evidence for phase coexistence is presented. Param eters are introduced which describe the volume fractions of phases, an d the overall amount of coexistence. This last parameter provides the basis for locating the nominal phase boundaries, and for an expression which describes the sharpness of any of the five smeared-out phase tr ansitions which occur in proton glass crystals.