Phase coexistence in proton glass

Abstract

Phase coexistence results from quenched structural randomness and frustrated interactions. The nature of this randomness and the frustrated interactions in proton glass are explained. The six types of ordered domains and corresponding ferroelectric and antiferroelectric phases are described, as well as the disordered paraelectric and proton glass phases. Experimental evidence for phase coexistence is presented. Parameters are introduced which describe the volume fractions of phases, and 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 transitions which occur in proton glass crystals.