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Characterization and optimization of the growth conditions of a novel Cs₂TeW₃O₁₂ piezoelectric crystal

Zhao, Peng, Wu, Qian, Gao, Zeliang, Tian, Xiangxin, Li, Conggang, Sun, Youxuan, Zhang, Chengqian, Xia, Shengqing, Tao, Xutang
RSC advances 2017 v.7 no.8 pp. 4278-4284
crystal structure, crystals, melting, temperature
In this study, Cs₂TeW₃O₁₂ (CTW) single crystals were grown successfully through a top-seeded solution growth (TSSG) method using TeO₂ as a self-flux. We identified a complete set of growth process parameters suitable for facilitating the growth of a high-quality CTW crystal. The results indicate that, in the same thermal field and with an appropriate flux ratio, a smaller cooling rate of the melt facilitates the smooth growth of high-quality CTW single crystals. The melt-viscosity versus temperature curves for different flux ratios were measured, and their effects on the crystal quality were discussed. In addition, the morphology of the crystal can be controlled by adjusting the rotation speed and the orientation of the seed. To investigate piezoelectric performance, complete sets of dielectric, elastic, and piezoelectric coefficients of CTW crystals were measured using both resonance and impedance analysis. The piezoelectric coefficients d₃₃ and d₁₅ reached 19.1 pC N⁻¹ and 25.9 pC N⁻¹, respectively. The electromechanical coupling coefficient, k₃₃, was 37.7%, slightly higher than that of Cs₂TeMo₃O₁₂ (CTM). Furthermore, the extent of dipole moment and polyhedron distortion of the CTW crystal were analysed in detail, and the relationship between the crystal structure and the piezoelectric properties was also discussed.