(K,Na)NbO3基无铅压电单晶的生长及性能研究

项目名称： (K,Na)NbO3基无铅压电单晶的生长及性能研究

项目编号： No.50862005

项目类型： 地区科学基金项目

立项/批准年度： 2009

项目学科： 轻工业、手工业

项目作者： 江向平

作者单位： 景德镇陶瓷学院

项目金额： 25万元

中文摘要： （K,Na）NbO3 （简称KNN）体系具有很高的压电、铁电性能，被认为是最有可能替代PZT的无铅压电材料，预计在准同型相界成分附近KNN固溶体单晶将表现出比陶瓷更为优越的压电性能，因此，开展KNN基单晶的生长及性能研究在基础理论及应用前景方面都具有重要的意义。本项目拟采用顶部籽晶助熔剂法生长KNN基单晶，利用逐步淘汰法培育KNN籽晶，通过调整生长速率、生长温度、籽晶旋转速率、KF/NaF助熔剂添加比例等晶体生长工艺参数，弄清晶体生长中组分分凝规律，以期最终生长出直径大于10mm、完整性好、高质量的KNN基以及Cu改性KNN单晶，研究晶体的电学性能随晶体组分、结构、结晶学取向等参数的变化规律，系统地表征晶体的压电、铁电、介电等性能，揭示该类无铅压电单晶的高压电活性的本质，探索KNN 基单晶高指数方向高压电性能的可能性，为推动无铅压电单晶的应用提供技术基础。

中文关键词： KNN基；无铅；晶体结构；电性能

英文摘要： (K,Na)NbO3（KNN）based material has attracted considerable attention because of its potential application as a lead-free piezoelectric candidate. However, many researches were focused on KNN-based ceramic materials, and little investigation has been carried out on KNN-based single crystals. In this project, lead free ferroelectric <001>-oriented KNN crystals with pure orthorhombic perovskite-type lattice have been obtained by melt grown technique. SEM observation has revealed the growth steps aligning approximately along [001] direction. Base on the model of negative ion coordination polyhedrons, it was revealed that the layer growth mechanism was dominating for the [001] face. The dielectric, ferroelectric and piezoelectric properties of KNN were investigated. (Na1/2Bi1/2)TiO3-BaTiO3 single crystal with the diameter of 4cm and thickness of 1cm have been grown by TSSG technique,and the Maximum d33 value of 360pC/N was obtained for the crystal.The structural, electronic and dielectric properties of KNN crystal were calculated by the first principle. In addition, Bismuth layer and KNN-based lead-free piezoelectric ceramics were also investigated. It was found that the piezoelectric properties of KNN ceramics were enhanced after doping of (K,Bi)TiO3、(Li,Bi)TiO3, which greatly promote the practical application of lead-free piezoelectric materials with technical foundation.

英文关键词： KNN-base; lead free; crystal structure; electric properties