Dielectric, ferroelectric and field-induced strain behavior of K_0.5Na_0.5NbO₃-modified Bi_0.5(Na_0.78K_0.22)_0.5TiO₃ lead-free ceramics

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• 作者：Ali Hussain^a ; ^b ; ^c ; Chang Won Ahn^b ; Aman Ullah^b ; Jae Shin Lee^d ; Ill Won Kim^b ; ^{kimiw@mail.ulsan.ac.kr}
• 关键词：C. Dielectric response ; Ferroelectrics ; Piezoelectricity ; Electrostriction ; Order&ndash ; disorder effects
• 刊名：Ceramics International
• 出版年：2012
• 期刊代码：13_02728842
• 类别：ms
• 出版时间：July, 2012
• 卷：38
• 期：5
• 页码：4143-4149
• 文件大小：1283 K

摘要

Lead-free piezoelectric (1 鈭?#xA0;x)Bi_0.5(Na_0.78K_0.22)_0.5TiO₃-xK_0.5Na_0.5NbO₃ (BNKT-xKNN, x = 0-0.10) ceramics were synthesized using a conventional, solid-state reaction method. The effect of KNN addition on BNKT ceramics was investigated through X-ray diffraction (XRD), dielectric, ferroelectric and electric field-induced strain characterizations. XRD revealed a pure perovskite phase with tetragonal symmetry in the studied composition range. As the KNN content increased, the depolarization temperature (T_d) as well as maximum dielectric constant (蓻_m) decreased. The addition of KNN destabilized the ferroelectric order of BNKT ceramics exhibiting a pinched-type hysteresis loop with low remnant polarization (11 渭C/cm²) and small piezoelectric constant (27 pC/N) at 3 mol%KNN. As a result, at x = 0.03 a significant enhancement of 0.22%was observed in the electric field-induced strain, which corresponds to a normalized strain (S_max/E_max) of 鈭?34 pm/V. This enhancement is attributed to the coexistence of ferroelectric and non-polar phases at room temperature.