Local atomic structure and morphotropic phase boundary

While the crystallographic structure shows a sharp change at the morphotropic phase boundary (MPB), the local atomic structure, determined by,by the pulsed neutron atomic pair-density function (PDF), varies continuously across the boundary. This implies that local properties change smoothly, across the boundary, and the nature of the transition is of the order/disorder type. It poses a serious question on placing undue emphasis on symmetry, and suggests that we should take a local view in trying to understand the phenomena related to the MPB, such as piezoelectricity in PZT.