Abstract—Lead free piezoelectric single crystals of (K_0.5Na_0.5)NbO₃ have been successfully grown by the high temperature flux solution method using B₂O₃ flux. Structure of the grown KNN single crystals was confirmed by powder X-ray diffraction analysis. The chemical composition of the as-grown single crystal was determined by Energy Dispersive X-ray analysis (EDS). Dielectric properties and the domain structure of KNN single crystals were investigated. The two phase transition temperatures of orthorhombic-to- tetragonal (O-to-T) and tetragonal-to-cubic (T-to-C) are found to be around 210°C and 429°C respectively for KNN single crystals as revealed from the dielectric measurements. The surface roughness was estimated to be about 6.96nm at room temperature using AFM studies. The Raman spectrum shows the characteristic peaks υ1, υ2 and υ5 of KNN single crystals, which are correlated to the internal vibrations of the NbO6 octahedron. The formation of single crystal of (K_0.5Na_0.5)NbO₃ requires sintering below 1000°C to avoid the problem of potassium volatilization.

Index Terms—Dielectric properties, flux method, raman spectrum, single crystal etc.

R. Saravanan and M. Chitra are with the Crystal Growth Centre, Anna University, Chennai.
D. Rajesh is with the G.T. Sollar Cell, China.
S. V. Rajasekaran is with the Govement Arts and Science College, Dharmapuri.
R. Perumal is with the Hanyang University, Seoul, South Korea.
R. Jayavel is with the Centre for Nanoscience and Technology, Anna University, Chennai (e-mail: rjvel@annauni.edu, Tel.: +91-44-2235 8328, fax: +91-44-2230 1656).

Cite: R. Saravanan, D. Rajesh, S. V. Rajasekaran, R. Perumal, M. Chitra, and R. Jayavel, "Crystal Growth and Dielectric Properties of Na_0.5K_0.5NbO₃ Single Crystal Grown by Flux Method Using B₂O₃ Flux," International Journal of Applied Physics and Mathematics  vol. 2, no. 3, pp.  190-193, 2012.