Monoclinic morphotropic phase and grain size-induced polarization rotation in Pb(Mg1∕3Nb2∕3)O3–PbTiO3

A detailed Rietveld analysis of x-ray data, collected at room temperature, was done on ceramics with controlled grain size between 100nm and 4μm for (PbMg1∕3Nb2∕3O3)0.80–(PbTiO3)0.20 (PMN-PT20), i.e., a compound at the border of the so-called morphotropic phase boundary. With size reduction the polarization rotates within the monoclinic plane from MB, i.e., Px=Py>Pz to MA, i.e., Px=Py