Improvement in temperature stability and modified polymorphic phase transition of La-doped (Na_0.52K_0.44Li_0.04) Nb_0.8Ta_0.2O₃ lead-free piezoelectric ceramics

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• 作者：Wenlong Yang ; Zhongxiang Zhou ; ^{zhouzx@hit.edu.cn} ; Bin Yang ; Yongyuan Jiang ; Huan Li ; Yanbo Pei
• 关键词：Polymorphic phase transition ; Temperature stability ; Piezoelectric materials ; Electrical properties
• 刊名：Materials Letters
• 出版年：2012
• 出版时间：1 March 2012
• 年：2012
• 卷：70
• 期：Complete
• 页码：146-148
• 全文大小：445 K

文摘

Lead-free ceramics (Na_0.52K_0.44Li_0.04)_1-3xLa_xNb_0.8Ta_0.2O₃ (KNLNT-Lax, x = 0.00-1.25 mol % ) were prepared by traditional method. The piezoelectric proprieties and the polymorphic phase transition behaviors around the room temperature were investigated. The results show that high density (¦Ñ ~ 95 % ) and outstanding piezoelectric performance (d₃₃ ?#xA0;200 pC/N, k_p ?#xA0;40 % ) were obtained with 0.5-0.75 mol % La doping. By the research of temperature dependent ¦Å_r, ¦¤f_r/f_r20 ¡ãC, and k_p, we acquired the extended and mild polymorphic phase transition region, and obvious improvement of temperature stability in ?#xA0;50-80 ¡ãC with the maximum derivation d(¦¤f_r/f_r20 ¡ãC)_max less than 2 % , as the La doping content exceeds 0.5 mol % . The possible mechanism of enhanced properties and temperature stability was analyzed. Both excellent piezoelectric and temperature stability characteristics make the La-doped KNLNT ceramics feasible for practical applications.