Elastic properties of zinc tris(thiourea) sulphate single crystals

Abstract

Zinc tris(thiourea) sulphate (ZTS) single crystals possess excellent nonlinear optical properties and are nearly 1.2 times more efficient than potassium dihydrogen phosphate in optical harmonic generation. Large single crystals of this material have been grown from aqueous solution. All nine second order elastic stiffness constants of this orthorhombic crystal have been determined by measuring the velocity of propagation of ultrasonic waves of longitudinal and transverse polarizations along specific symmetry directions. The McSkimin Δt correction has been applied for better accuracy of velocity values. The corresponding elastic compliance constants and Poisson’s ratios have also been evaluated. Planar plots of phase velocity, group velocity, slowness, Young’s modulus, and linear compressibility have been drawn to display the anisotropy of wave propagation in the crystal. The bulk modulus and volume compressibility of this crystal have been evaluated from the elastic constant data. Variation of a selected number of elastic constants with temperature in a limited range have also been measured and reported.