The effect of different dopants on diffuse phase transition and ordering degree in PMN

This work is based on PMN system. The influences of different dopants (Li⁺, Sr²⁺, Y³⁺) on diffuse dielectric properties and micro-structure were studied. HREM, SAED, Raman spectra and XPS were used to study small changes of ordering degree of PMN systems. The research proved that diffuse phase transition (DPT) is caused by the formation of ordered structure at B site (Mg²⁺:Nb⁵⁺=1:1). The degree of DPT can be contrasted from dielectric properties, and has direct relation with ordering degree of microstructure. It also showed when doping with element of one valence (Li⁺), the ordering degree of PMN lowered; when doping with Sr²⁺ and Y³⁺, the ordering degree enhanced to different extent.