铌酸铋钠基压电织构陶瓷的高温压电性能及导电机制研究

Bismuth layer-structured ferroelectrics bismuth sodium niobate (Na0.5Bi2.5Nb2O9,NBN)based piezoelectric ceramics are potentially used in high temperatue piezoelectric sensors because of their high Curie temperature Tc.However, there are some critical issues, such as the enhancement of piezoelectric property, the relationship between structure， doping and properties, the optimized processing of ceramics,characterization of piezoelectric property at high temperature, and the mechanisms of extrinsic and intrinsic conduction etc., needed to be solved further.This proposal will mainly focus on the following three vital scientific problems. Firstly, what is the principle of doping and compositional designing of NBN based piezoelectric ceramics. Secondly, what is the relationship between performances and a new templated grain growth process based upon rolling forming technique. Finally, what is the mechanisms of intrinsic and extrinsic conduction of NBN-based piezoelectric ceramics and how to characterize the piezoelectric property of NBN-based ceramics at high temperature. The aims of this proposal are as follows:The first is to achieve optimum compositions of NBN-based high temperature piezoelectric ceramic with excellent properties.The second is to master a new templated grain growth process based on rolling forming technique,which favors the preparation of NBN-based textured ceramics with controllable grain orientation, high Tc, and high piezoelectric constant d33. Finally, this proposal is to reveal the temperature dependent behaviors of conductivity and d33 of NBN-base ceramics, which favors the design and fabrication of high temperature piezoelectric sensors.

铋层状铁电体Na0.5Bi2.5Nb2O9(NBN)基压电陶瓷因其高居里温度Tc(>785℃)在高温压电传感器中有重要潜在应用。但其压电活性的提高、陶瓷结构、掺杂与性能的关联、陶瓷制备工艺的优化、高温下压电性能的表征、本征与非本征导电机制等关键问题需进一步解决。针对上述问题，本项目将重点解决以下三个关键科学问题：(1)、NBN基高温压电陶瓷的掺杂及组分设计原则；（2）、基于陶瓷轧膜工艺的模板晶粒生长新工艺与NBN基高温压电陶瓷性能的关联；（3）、NBN基高温压电陶瓷本征与非本征导电机制及其高温压电性能的表征方法。通过本项目的研究，可望获得性能优异的NBN基高温压电陶瓷组成，掌握具有高Tc、高d33，且晶粒取向度可控的NBN基高温压电织构陶瓷制备工艺；掌握NBN基高温压电陶瓷电导率及压电性的温度变化特性，这对于高温压电传感器的设计具有重要意义。因而本项目研究具有重要的科学意义和应用价值。

随着工业及科学技术的发展，汽车电子、航空航天、清洁能源（如核能、风能、地热能）等领域对高温压电传感器提出了迫切需求。研究和开发具有良好压电性、高居里温度的高温压电陶瓷材料具有现实的紧迫性和必要性。本项目选择铋层状铁电体化合物铌酸铋钠体系，深入开展了陶瓷的组分设计、陶瓷的结构及性能等基础研究。本项目在执行期间，重点研究了如下关键科学问题：NBN基高温压电陶瓷的掺杂及组分设计原则；模板晶粒制备工艺、高温压电性能的表征方法及高温导电机制。特别是，在NBN的基高温压电陶瓷的掺杂及组分设计，取得了重要进展；在高温导电机制及高温压电性能表征取得了突破；采用常规的、传统的陶瓷制备工艺技术，获得了d33≥26 pC/N，TC≥790℃，在室温到775℃范围几乎无退极化的高温压电陶瓷材料组成；获得了d33≥17 pC/N，TC≥930℃，在室温到850℃范围退极化幅度仅为12%的高温压电陶瓷材料组成；正式发表SCI和EI核心期刊收录论文13篇；获得授权国家发明专利1份；培养博士1人，培养硕士6人，其中1位已获硕士学位。