磁场作用下弛豫铁电晶体生长过程中的偏析研究

项目名称： 磁场作用下弛豫铁电晶体生长过程中的偏析研究

项目编号： No.51472197

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 惠增哲

作者单位： 西安工业大学

项目金额： 82万元

中文摘要： 大尺寸弛豫铁电晶体的成功生长已有十多年的历史，但至今应用并不象预想的那样广泛，主要原因是Bridgman法生长的晶体中组分不均匀，从而导致其电学性能不一致。针对这一背景，本项目拟将直流静磁场引入PMN-PT和PMN-PSN-PT晶体生长过程，借助于直流静磁场的洛仑兹力抑制固-液界面前沿熔体的对流，保持固-液界面前沿低熔点组分的富集，以减小晶体生长过程中的轴向组分偏析，提高晶体组分和性能的均匀性；通过直流静磁场对界面和表面的微区作用，减少其它晶体缺陷。拟主要研究直流静磁场作用下弛豫铁电晶体生长过程中的熔体对流形态及其对晶体组分偏析、缺陷分布和电学性能的影响规律；优化弛豫铁电晶体的Bridgman法生长技术，生长组分均匀、大尺寸的PMN-PT和PMN-PSN-PT晶体；研究所生长晶体的介电、压电、铁电特性及其与相结构、缺陷、电畴组态之间的内在联系。

中文关键词： 晶体生长；铁电；组分偏析；弛豫

英文摘要： Relaxor ferroelectric crystal with large size has been grown successfully for decade, but it is not been widely used as expected. The major reason is that the composition of the crystal grown by Bridgman method is not homogeneous, which leads to the non-uniformity of electric properties of the crystal. Based on the situation, in this project static magnetic field is introduced to the growth process of PMN-PT and PMN-PSN-PT crystals. The convection in the melt is restrained by Lorentz force, which keeps gathering of lower-melting-point composition in the melt in front of S/L interface. The gathering reduces the composition segregation along axial direction during the crystal growth, which increases the homogeneity of the composition and the properties of the crystal. Other crystal defect is decreased with the help of the local effects of static magnetic field on the interface and surface. During crystal growth under static magnetic field the convection pattern in the melt and its effect on the composition segregation, defect distribution and electric properties of crystal are studied. The crystal growth technique with Bridgman method is optimized. The PMN-PT and PMN-PSN-PT crystals with large size and homogeneous composition are grown. The characteristics of dielectric, piezoelectric and ferroelectric of the grown crystal are studied. Meanwhile, the relationship among the phase structure, defect, domain configuration and the characteristics of dielectric, piezoelectric, ferroelectric are studied.

英文关键词： crystal growth;ferroelectric;composition segregation;relaxor