Cycling stability of lead-free BNT-8BT and BNT-6BT-3KNN multilayer actuators and bulk ceramics

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• 作者：Eva Sapper ; Andrea Gassmann ; Lars Gj酶dvad ; Wook Jo ; Torsten Granzow ; J眉rgen R枚del
• 关键词：Bismuth sodium titanate ; Lead-free ; Multilayer actuator ; Strain hysteresis ; Fatigue
• 刊名：Journal of the European Ceramic Society
• 出版年：March, 2014
• 年：2014
• 卷：34
• 期：3
• 页码：653-661
• 全文大小：2498 K

文摘

This study presents the electromechanical properties and cycling stability of lead-free piezoelectric materials 0.92(Bi_1/2Na_1/2)TiO₃-0.08BaTiO₃ (BNT-8BT) and 0.91(Bi_1/2Na_1/2)TiO₃-0.06BaTiO₃-0.03(K_0.5Na_0.5)NbO₃ (BNT-6BT-3KNN). Both bulk samples as well as multilayer actuators (MLA) with internal Ag/Pd (70/30) electrodes were successfully processed from both materials. Electromechanical characteristics in the non-fatigued state and after different numbers of unipolar fatigue cycles are provided, representing the first direct comparison of the fatigue resistance of lead-free bulk ceramics and the corresponding MLAs. At a maximum field of 6 kV/mm and a frequency of 50 Hz, BNT-8BT MLA delivered a maximum strain of 0.07% and displayed excellent cycling stability. BNT-6BT-3KNN MLA provided a higher strain of 0.15% initially but degraded during cycling and exhibited break down after 10⁷ cycles. Furthermore, the frequency dependence of strain and the self-heating during cycling were investigated. The temperature increase is limited only to 2 掳C in BNT-8BT MLA and 13 掳C in BNT-6BT-3KNN MLA.