Phase Relations in the Na_(0.5)Bi_(0.5)TiO_3-Li_(3x)La_((2/3)-x) □_((1/3)-2x) TiO_3 System

摘要

The phase relations and the mechanism of solid-state synthesis for the Na_(0.5)Bi_0.5TiO_3-Li_3xLa_((2/3)-x)□_((1/3)-2x)TiO_3 system were investigated using X-ray powder diffraction, scanning electron microscopy, and thermal analysis. The study revealed that the extent of the homogeneity range—which is related to the A-site substitution between (Na_(0.5)Bi_(0.5) and (Li_(3x).La_((2/3)-x)□_(1/3)-2x) pseudo cations of a perovskite structure—depends strongly on the ordering of the (Li_(3X)La_((2/3)-x)-□_(1/3)-2x) + species. The solid-state reaction of the compounds in the homogeneity range is completed only after multiple high-temperature firings. However, the system is also subjected to a slow thermal decomposition; this is particularly so for the compounds with a high x value and an increased Li_(3x),.La_((2/3)-x□_((1i/3)-2x)TiO_3 concentration.