新型无铅压电单晶KNN的生长与性能研究

项目名称： 新型无铅压电单晶KNN的生长与性能研究

项目编号： No.50872106

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 李振荣

作者单位： 西安交通大学

项目金额： 32万元

中文摘要： (K,Na)NbO3（KNN）体系材料被认为是有望替代PZT 压电陶瓷的无铅压电材料，KNN单晶的研究对于探索无铅压电材料具有重要学术原创意义。本研究拟围绕KNN准同型相界组成，采用改性的坩埚下降法生长KNN单晶，并通过优化工艺参数，获得组成均匀质量稳定的KNN单晶材料；研究[100]、[110]和[111]取向单晶的介电温度谱、偏压下的介电温度谱和压电性能以及铁电和电致应变性能，对材料性能进行全面科学评价；观察单晶的畴结构，揭示微观结构随温度、偏压的变化规律，结合宏观性能，探索碱金属铌酸盐材料体系的极化机制。本项目有助于发展高性能无铅压电单晶的制备科学，同时开展性能与极化机制的研究，为推动无铅压电单晶的应用奠定基础。

中文关键词： KNN单晶生长；介电性能；压电性能；畴结构

英文摘要： The research and development of lead-free piezoelectric single crystals with high performance is an important direction in piezoelectric materials area. In this project, the growth, dielectric properties，piezoelectric properties and polarization mechanism of (KxNa1-x)NbO3 (KNN) and Mn-(K0.5Na0.5)NbO3 (Mn-KNN) single crystals were investigated based on KNbO3-NaNbO3 system . A series of KNN single crystals with different composition were successfully grown by high temperature solution method and Bridgman method. The highest piezoelectric constant (d33) of KNN single crystal is about 167pC/N. The piezoelectric constant (d33) of MnO2 doping KNN single crystal was found as high as 280pC/N, higher than that in literatures. From the application view point, the temperature stability of [001]-oriented KNN and Mn-KNN single crystals were investigated. It was found that the piezoelectric constant were stable from 25oC to 180 oC. Based on the investigation of polarization mechanism, the best piezoelectric constant was obtained in the [001]-oriented KNN and Mn-KNN single crystals poled near 120 oC ~130 oC. Furthermore, the domain walls were stable at the temperature between the rhombohedral- orthorhombic phase transition and orthorhombic-tetragonal phase transition. Finally, the contrastive research of NaNbO3-KNbO3 system has been done between experiment data and traditional phase diagram.

英文关键词： KNN single crystal growth; dielectric properties; piezoeelctric properties; domain structure;