Effects of Ge⁴⁺ acceptor dopant on sintering and electrical properties of (K_0.5Na_0.5)NbO₃ lead-free piezoceramics

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• 作者：Kepi Chen ; Yanlin Jiao
• 关键词：lead ; free piezoelectric ceramics ; potassium sodium niobate ; doping ; sintering ; dielectric relaxation ; piezoelectric properties
• 刊名：Frontiers of Materials Science
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：11
• 期：1
• 页码：59-65
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Materials Science, general;
• 出版者：Higher Education Press
• ISSN：2095-0268
• 卷排序：11

文摘

Lead-free (K_0.5Na_0.5)(Nb_1-xGe_x)O₃ (KNN-xGe, where x = 0-0.01) piezoelectric ceramics were prepared by conventional ceramic processing. The effects of Ge4+ cation doping on the phase compositions, microstructure and electrical properties of KNN ceramics were studied. SEM images show that Ge4+ cation doping improved the sintering and promoted the grain growth of the KNN ceramics. Dielectric and ferroelectric measurements proved that Ge4+ cations substituted Nb5+ ions as acceptors, and the Curie temperature (T_C) shows an almost linear decrease with increasing the Ge4+ content. Combining this result with microstructure observations and electrical measurements, it is concluded that the optimal sintering temperature for KNN-xGe ceramics was 1020°C. Ge4+ doping less than 0.4 mol.%can improve the compositional homogeneity and piezoelectric properties of KNN ceramics. The KNN-xGe ceramics with x = 0.2% exhibited the best piezoelectric properties: piezoelectric constant d₃₃ = 120 pC/N, planar electromechanical coupling coefficient k_p = 34.7%, mechanical quality factor Q_m = 130, and tanδ = 3.6%.