Effect of Excess PbO on the Kinetics of the Growth of PMNT Polycrystals by Templated Grain Growth Method

摘要

The oriented 0.67Pb (Mg_(1/3)Nb_(2/3))O_3-0.33PbTiO_3 (PMNT) polycrystals were prepared by the conventional ceramic technique and the templated grain growth method adding excess PbO in the matrix. Kinetics of the development of oriented structure was investigated systemically. In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grow by the dissolution-precipitation mechanism. The diffusion is determined by the sintering temperature and the PbO-excess content in the matrix. The thickness of oriented PMNT polycrystals displays a t~(1/3) dependence, which is characteristic of diffusion-controlled growth. For the thicker oriented structure, 20% excess PbO in the PMNT matrix and 1150℃ for 10h are the proper experimental conditions. Moreover, the addition of PbO in the matrix hardly affects the final composition of ceramic matrix.