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

The compositional fluctuation and correlation between the ordered domain an d the polar cluster in lead magnesium niobate Pb(Mg1/3Nb2/3)O-3 have been s tudied by analytical electron microscopy and the image processing technique . It indicates that there is a strong compositional fluctuation of Mg/Nb ra tio 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 eit her the ordered or disordered regions. Antiphase domain boundaries and disl ocations were found, with the boundary facets of ordered domains being prim arily {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 a nd dislocation area were found to be a region of severe distortion. The ran dom interdomain-boundary area, with strong compositional fluctuation and la ttice strain, may play an important role in forming a center for polar clus ters. (C) 2001 American Institute of Physics.