Growth, optical and thermal properties of near-stoichiometric LiNbO 3 single crystal

Abstract

A near-stoichiometric LiNbO 3 (N-SLN) single crystal of 40 mm in diameter and 60 mm in length has been grown by Czochralski method from a 58.5% Li melt in a platinum crucible. The fundamental absorption edge and IR absorption spectra were used for determining Li/Nb of the crystal. The measured specific heat of the crystal to be 0.6995 J g −1 K −1 is larger than that of congruent LiNbO 3 (CLN) crystal to be 0.6010 J g −1 K −1 at 303.15 K. The thermal expansion coefficients along the two crystallographic directions in the measuring temperature range of 303.15–767.15 K have been measured to be a a = a b = 17.1807 K × 10 −6 K and a c = 2.8769 K × 10 −6 K, respectively. Thermal conductivity of near-stoichiometric LiNbO 3 crystal is 5.234 W/m K and 4.434 W/m K at room temperature. The reason for larger anisotropic thermal expansion coefficients and larger thermal conductivity of N-SLN crystal than those of CLN crystal were discussed according to the structure of LiNbO 3 crystal.