过量PbO对TGG法定向生长PMNT多晶体动力学影响的研究

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

采用传统陶瓷工艺和添加过量 Pb O的 TGG方法实现了 PMNT多晶体沿 <0 0 1>方向的定向生长 ,对多晶体定向生长的动力学进行了详细的研究。结果表明 ,PMNT多晶体定向生长的厚度随过量 Pb O的增加而线性增加 ,它的生长是热激活扩散与溶解 -沉积过程二者综合作用的结果。只要选择适当的生长时间 ,在 PMNT基体中添加过量的Pb O,不但不会影响陶瓷的组分还可以显著提高多晶体的定向生长速度。而且 ,PMNT多晶体定向生长厚度与生长时间的 1/3方呈线性关系 ,属于典型的扩散控制的生长行为。实验表明 ,采用添加 2 0 %过量的 Pb O、在 115 0℃生长10 h是制备

The oriented 0.67Pb(Mg_(1/3)Nb_(2/3))O_3-0.33PbTiO_3 (PMNT67/33) polycrystals were prepared by the conventional ceramic technique and the Templated Grain Growth (TGG) method adding excess PbO.Kinetics of the development of oriented structure was investigated in detail.In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grew by the dissolution-precipitation mechanism.The diffusion was determined by the sintering temperature and the excess PbO concentration.A thicker oriented crystal layer was obtained if more PbO in the matrix was present.Moreover, the addition of excess PbO in the matrix can hardly affect the composition of ceramics because most of the PbO evaporated after sintered above 1100℃ for 10h.The thickness of oriented PMNT polycrystals displayed 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 were the proper process conditions.