Neutron diffraction study of electrostrictive coefficients of prototype cubic phase of relaxer ferroelectric PhMg1/3 Nb2/3 O3

The electrostrictive coefficients of prototype cubic phase of PbMg1/3Nb2/3O3 are studied using a high-resolution neutron powder diffraction experiment. The key idea of the approach is to "eliminate" from the material the inhomogeneity related to the presence of the double-phase mixture "polar regions/nonpolar matrix," and to study two structurally homogeneous states: prototype cubic at temperatures above 600 K and rhombohedral ferroelectric at temperatures below 220 K. The obtained value of volumetric electrostrictive coefficient. O-h=(8.3+/-1.0)x10(-2) x(m(4)/C-2), is consistent with those of other perovskite ferroelectrics with a prototype cubic phase. (C) 1998 American Institute of Physics.