A neutron powder diffraction study of short range order in ferroelectric Pb(Mg(1/3)Nb(2/3))O(3).

The structure of Pb(Mg(1/3)Nb(2/3))O(3) (PMN) was investigated using pulsed neutron powder diffraction. Rietveld analysis suggests small displacements of Pb and O atoms, with anomalously large thermal factors. The pair-distribution function (PDF) derived from experiment indicates the presence of short range order. Modeling in real space by fitting to the experimental PDF suggests displacements of lead and oxygen atoms of much larger magnitude than those indicated by the Rietveld analysis. Correlation of these displacements may be related to the onset of bulk ferroelectricity in this material.