Ordered domains and polar clusters in lead magnesium niobate Pb(Mg1/3Nb2/3)O3

The compositional fluctuation and correlation between the ordered domain and the polar cluster in lead magnesium niobate Pb(Mg1/3Nb2/3)O-3 have been studied by analytical electron microscopy and the image processing technique. It indicates that there is a strong compositional fluctuation of Mg/Nb ratio in both the ordered and the disordered regions, and that the degree of fluctuation of the Mg/Nb ratio is stronger in the boundary area than in either the ordered or disordered regions. Antiphase domain boundaries and dislocations were found, with the boundary facets of ordered domains being primarily {111} with a lesser {001} orientation. The fringe image of Nb and (Nb+Mg) is distorted randomly, which is thought to be caused by compositional fluctuation of the Mg/Nb ratio and local layer displacement. The boundary and dislocation area were found to be a region of severe distortion. The random interdomain-boundary area, with strong compositional fluctuation and lattice strain, may play an important role in forming a center for polar clusters. (C) 2001 American Institute of Physics.