铋基无铅压电陶瓷Bi0.5(Na0.82K0.18)0.5TiO3-BiCrO3的微观组织与电性能

采用传统陶瓷制备方法,制备一种新型无铅压电陶瓷 (1-x)Bi0.5(Na0.82K0.18)0.5TiO3-xBiCrO3 (BNKT-BCx).研究Bi基铁电体BiCrO3对BNKT-BCx陶瓷晶体结构和压电介电性能的影响.结果表明:在所研究的组成范围内,陶瓷材料的主体结构为纯钙钛矿固溶体,微量BiCrO3(x=0～0.02,摩尔分数)不改变陶瓷的晶体结构;当BiCrO3含量x＞0.02时,晶体结构由三方、四方共存转变为伪立方结构,并出现明显的第二相;当x=0.015时,d33=168 pC/N;当x=0.01时,kp=0.32,为该体系压电性能的最大值;随BiCrO3含量的增加,陶瓷的低温介电反常峰向低温移动,高温介电反常峰向高温移动,反铁电相区域增加,弥散指数增加.

Microstructure and electrical properties of Bi-based lead-free piezoelectric ceramics Bi0.5(Na0.82K0.18)0.5TiO3-BiCrO3

A new (Bi0.5Na0.5)TiO3-based lead-free piezoelectric ceramics, (1-x)Bi0.5(Na0.82K0.18)0.5TiO3-xBiCrO3 (BNKT-BCx), was prepared by a conventional ceramic sintering technique. The effect of Bi-based ferroelectrics of BiCrO3 on the crystal structure, dielectric and piezoelectric properties was investigated. X-ray diffraction patterns indicate that trace BiCrO3 addition(x=0-0.02) causes insignificant change in crystal structure, and an obvious secondary phase is observed in the samples with x＞0.02. The piezoelectric constant d33 and the electromechanical coupling factor kp of the ceramics attain maximum values of 168 pC/N and 0.32 near morphotropic phase boundary (MPB) that co-existence between rhombohedral and tetragonal. With increasing BiCrO3 content, the antiferroelectric phase zone gets broader and the diffuse coefficient increases.