Composition and temperature dependence of structure and piezoelectricity in (1−x)(K_1−yNa_y)NbO₃-x(Bi_1/2Na_1/2)ZrO₃ lead-free ceramics

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• 作者：Dawei Wang ; Fayaz Hussain ; Amir Khesro ; Antonio Feteira ; Ye Tian ; Quanliang Zhao and Ian M. Reaney
• 刊名：Journal of the American Ceramic Society
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：100
• 期：2
• 页码：627-637
• 全文大小：3094K
• ISSN：1551-2916

文摘

Lead-free piezoceramics with the composition (1−x)(K_1−yNa_y)NbO₃-x(Bi_1/2Na_1/2)ZrO₃ (KNyN-xBNZ) were prepared using a conventional solid-state route. X-ray diffraction, Raman spectroscopy, and dielectric measurements as a function of temperature indicated the coexistence of rhombohedral (R) and tetragonal (T) phase, typical of a morphotropic phase boundary (MPB) as the BNZ concentration increased and by adjusting the K/Na ratio. High remnant polarization (P_r=24 μC/cm²), piezoelectric coefficient (d₃₃=320 pC/N), effective piezocoefficient ({d_{33}^*}=420 pm/V), coupling coefficient (k_p=48%), and high strain (S=0.168%) were obtained at room temperature, but significant deterioration of P_r, {d_{33}^*}, and k_p were observed by increasing from room temperature to 160°C (17.5 μC/cm², 338 pm/V, and 32%, respectively) associated with a transition to a purely T phase. Despite these compositions showing promise for room-temperature applications, the deterioration in properties as a function of increasing temperature poses challenges for device design and remains to be resolved.