Unique three-phase states in (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 single crystals

Abstract

This paper reports results on the crystallographic study of heterophase structures in relaxor–ferroelectric(1−x)Pb (Zn1/3Nb2/3)O3–xPbTiO3 singlecrystals with 0.06<x<0.11. Possible variants of the elastic matching of three ferroelectric polydomain or twinnedphases are considered with due regard for the relief of internal stresses at various volumefractions of these phases near the morphotropic phase boundary. It is found thattwo-phase regions, ‘rhombohedral–monoclinic’ and ‘monoclinic–tetragonal’, can beelastically matched along so-called zero-net-strain planes, parallel to the (100) or (010)domain (twin) walls in the intermediate monoclinic phase, where the Miller indices(hkl) are written in terms of the perovskite axes of the cubic unitcell. Calculated volume fractions of the three phases coexisting at0.06<x<0.11 agree well with recent experimental results obtained by Bertram et al (2003 J. Cryst. Growth253 212).