KNN基无铅压电陶瓷相界研究进展

Research Progress on Phase Boundary of KNN-based Lead-free Piezoelectric Ceramics

压电陶瓷是实现机械能与电能相互转换的重要功能材料。目前,以锆钛酸铅(PZT)为代表的铅基压电陶瓷因具有优异的综合电学性能被广泛用于传感器、执行器和换能器等许多商业高科技电子产品。然而,金属铅的毒性以及易挥发性会对生态环境造成极大损害。近年来,许多国家已立法限制使用含铅的电子产品。因此,压电陶瓷无铅化成为国内外学者的研究重点。而在各类无铅压电陶瓷中,铌酸钾钠(KNN)基无铅压电陶瓷因具有优异的压电、介电性能和较高的居里温度,被认为是取代铅基压电陶瓷的理想材料之一。多年来,研究者通过调节K/Na比、离子掺杂、添加新组元等方式构建室温下KNN基陶瓷多相共存相界(如准同型相界(MPB)或多晶型相界(PPB))。多相共存相界下各个相势垒较低,极化方向增加,电畴易发生翻转,从而使陶瓷产生高的压电效应。目前,KNN基无铅压电陶瓷因具有纳米级三方相(R)-正交相(O)-四方相(T)三相共存相界,其压电性能已超过某些铅基压电陶瓷。超高的压电性能来源于新型相界(NPB)的构建。结合近年来相关文献,本文以相界作为出发点,综述了国内外KNN基无铅陶瓷中MPB、PPB以及NPB的最新研究进展;重点阐述了陶瓷体系成分和晶粒尺寸对构建相界以及调控压电性能相关文献的最新报导;分析了KNN无铅压电陶瓷在相界研究方向上面临的问题并展望其前景。以此为开发高性能无铅压电陶瓷提供参考。

Piezoelectric ceramics are important functional materials to realize the mutual conversion of mechanical energy and electrical energy.Lead-based piezoelectric ceramics represented by lead zirconate titanate(PZT)are currently widely used in many commercial high-tech electronic products such as sensors,actuators and transducers due to their excellent comprehensive electrical properties.However,the toxicity and volatility of metal lead will cause great damage to the ecological environment.In recent years,many countries have legislated to restrict the use of lead-containing electronic products.Therefore,lead-free piezoelectric ceramics has become the research focus of domestic and foreign scholars.In various lead-free piezoelectric ceramics.Potassium sodium niobate(KNN)-based lead-free piezoelectric ceramics are considered as one of the ideal materials to replace lead-based piezoelectric ceramics due to their excellent piezoelectric and dielectric properties and high Curie tempe-rature.Over the years,researchers have constructed multiphase coexistence phase boundaries such as quasi-homotypic phase boundaries(MPB)or polycrystalline phase boundaries(PPB)of KNN-based ceramics at room temperature by adjusting the K/Na ratio,ion doping,and adding new group components.Under the multiphase coexistence phase boundary,the potential barriers of each direction are lower,the polarization direction increases,and the electric domain is easily reversed,so that the ceramic has a high piezoelectric effect.At present,the piezoelectric performance of KNN-based lead-free piezoelectric ceramics exceeds that of some lead-based piezoelectric ceramics by constructing nanoscale tripartite(R)-orthogonal(O)-tetragonal(T)coexisting phase boundaries.The ultra-high piezoelectric performance comes from the construction of novel phase boundaries(NPBs).Combined with relevant literature in recent years,this paper takes the phase boundary as the starting point,and summarizes the latest research progress of MPB,PPB and NPB in KNN-based lead-free ceramics at home and abroad;the latest reports in the literature related to the construction of phase boundaries and the regulation of piezoelectric properties by the composition and grain size of ceramic systems are emphasized;the problems faced by KNN lead-free piezoelectric ceramics in the direction of phase boundary research are analyzed and their prospects are prospected,which provides a reference for the development of high-performance lead-free piezoelectric ceramics.