Low-temperature hydro/solvothermal synthesis of Ta-modified K0.5Na0.5NbO3 powders and piezoelectric properties of corresponding ceramics

• Published in: Materials in engineering Vol. 33; pp. 362 - 366
• Main Authors: Li, Lu, Gong, Yue-Qiu, Gong, Lun-Jun, Dong, Hui, Yi, Xi-Feng, Zheng, Xue-Jun
• Format: Journal Article
• Language: English
• Published: 01.01.2012
• Subjects: Ceramics; Crystal structure; Density; Optimization; Piezoelectricity; Sintering (powder metallurgy); Synthesis; Tantalum
• ISSN: 0261-3069
• DOI: 10.1016/j.matdes.2011.03.023

K0.5Na0.5Nb1-xTaxO3 (KNNTx, x = 0-0.4) powders were synthesised by a novel hydro/solvothermal method at a low reaction temperature (180 C) and the corresponding ceramics were obtained by normal sintering. Compared with the conventional solid-state reaction, the optimal sintering temperatures of these ceramics were reduced by at least 150 C. The crystalline structures and surface morphologies were analysed using XRD and SEM. Excellent piezoelectric properties were obtained by selecting a poling temperature near the orthorhombic-tetragonal polymorphic phase transition temperature region. Ta-modified KNN ceramics showed better piezoelectric properties than those of pure KNN, and the piezoelectric coefficient d33 showed the maximum value of 156 pC/N for KNNT0.3 ceramics. In addition, the sintering temperature for maximum d33 value differed from that for maximum density. The hydro/solvothermal method provides a new potential route for preparing KNN-based materials at relatively low temperature.