Effect of vanadium substitution on electrical and piezoelectric properties of lead-free (K_0.5Na_0.5)NbO₃ ceramics

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• 作者：Chongtham Jiten ; K. Chandramani Singh
• 刊名：Journal of Materials Science: Materials in Electronics
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：28
• 期：1
• 页码：507-513
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Optical and Electronic Materials; Characterization and Evaluation of Materials;
• 出版者：Springer US
• ISSN：1573-482X
• 卷排序：28

文摘

During the last decade, efforts have been made towards developing lead-free piezoelectric ceramics which can replace the currently dominant but highly superior lead-based piezoelectric materials such as PZT. (K_0.5Na_0.5)NbO₃-based piezoelectrics are one promising candidate because of their relatively high Curie temperatures and piezoelectric coefficients. In the present work, powders of (K_0.5Na_0.5)(Nb_1−xV_x)O₃ (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by conventional solid state reaction of K₂CO₃, Na₂CO₃, Nb₂O₅, and V₂O₅. The powders were high-energy milled in isopropyl alcohol medium using a Retsch PM 100 planetary ball mill at the speed of 200 rpm for 8 h. The milled powders were sintered at 1080 °C for 1 h in closed alumina crucible. The crystalline phase of the ceramics was found to be perovskite with orthorhombic symmetry. Increasing V5+ content in the ceramics from x = 0 to x = 0.03 gives rise to gradual increase in room temperature dielectric constant (ε_r) from 346 to 432, remnant polarization (P_r) from 6.2 to 9.6 μC/cm2, electromechanical coupling factor (k_p) from 0.35 to 0.39, and piezoelectric charge constant (d₃₃) from 76 to 93 pC/N. The increase in these parameters is attributed to the associated increase in density of the ceramics with increasing V5+ content. Further increase in V5+ content to x = 0.05 results in decrease in ε_r, P_r, k_p and d₃₃ to 390, 4.7 μC/cm2, 0.33 and 67 pC/N respectively. The study reveals that an optimum concentration of V5+ can enhance the dielectric, ferroelectric and piezoelectric properties of (K_0.5Na_0.5)NbO₃ system.