高性能铌酸钾钠基无铅陶瓷的压电和电卡性能

Piezoelectric and electrocaloric properties of high performance potassium sodium niobate-based lead-free ceramics

压电陶瓷作为一种能够实现机械能和电能相互转换的功能材料,在民用和军事方面都有着广泛应用.随着人们环保及健康意识的提高,高性能兼具环境协调性的无铅压电陶瓷的研究成为了一项紧迫任务.在众多无铅材料中,(K, Na)NbO3(KNN)基陶瓷因其优异的综合性能而受到关注,但是利用相界同时调控高压电和电卡性能的研究偏少.本文采用传统固相方法制备了0.944K0.48Na0.52Nb0.95Sb0.05O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3-1.6%(AgxNa1–x)SbO3-0.4%Fe2O3(x=0-1.0)无铅压电陶瓷,重点研究了AgSbO3/NaSbO3对陶瓷相结构、压电和电卡性能的影响.研究结果表明:陶瓷在研究组分范围内均为"三方-正交-四方"三相共存;随着AgSbO3含量的增加,该陶瓷的压电及铁电性能均有所波动(d33=518-563pC/N, kp=0.45-0.56, Pmax=21-23μC/cm2和Pr=14-17μC/cm2).同时,利用间接法表征了该陶瓷的电卡效应,在居里温度附近得到了较高的电卡温变值(>0.6 K).因此,在KNN基陶瓷中通过相界构建能够同时实现高压电和良好的电卡性能.

Piezoelectric ceramics,as a kind of functional material,can realize the mutual transformation between mechanical energy and electrical energy,and has been widely used in civil and military fields.With the improvement of people's awareness of environment protection and self-health care,the study of lead-free piezoelectric ceramics with excellent performance and environmental friendliness has become an urgent task.Among several kinds of lead-free piezoelectric materials,potassium sodium niobate[(K,Na)NbO3,KNN]-based ceramics has attracted much attention due to its good comprehensive properties,but there have been carried out few studies focusing on the utilization of phase boundary to regulate the properties of high piezoelectric and electrocaloric effect simultaneously.In this work,lead-free 0.944K0.48Na0.52Nb0.95Sb0.05O3-0.04Bi0.5(Na0.82K0.18)0.5 ZrO3-1.6%(AgxNa1–x)SbO3-0.4%Fe2O3 ceramics is prepared via the conventional solid-state method,and the effect of AS/NS ratio on phase structure,electrical properties,and electrocaloric effect are studied.The obtained results show that the ceramics has a multiphase coexistence with“rhombohedral-orthorhombictetragonal”(R-O-T)in all compositions.With the increase of AS content,the piezoelectric and ferroelectric properties of the ceramics fluctuate(d33=518–563 pC/N,kp=0.45–0.56;Pmax=21–23μC/cm^2,Pr=14–17μC/cm^2).In addition,the electrocaloric effect(ECE)for each of the samples is studied by the indirect method.Broadening temperature span(~90 K)of electrocaloric effect is obtained in the vicinity of O-T phase transition region,while a low ECE value is observed.A stronger ECE peak(DTmax>0.6 K)can be observed when the measurement temperature reaches near the Curie temperature.Consequently,both large piezoelectric property and high electrocaloric performance can be realized in KNN-based ceramics by new phase boundary construction.