Influence of pH on the Growth of Tris-Allylthiourea Cadmium Chloride Single Crystals

Single crystal growth of non-linear optical material tris-allylthiourea cadmium chloride (ATCC) single crystals has been investigated. The crystals were grown from aqueous solution by slow evaporation as well as by slow cooling technique. The influence of pH of the solution on the morphological and optical properties of the grown crystals was investigated. At pH 5-6, the crystals are elongated along a-axis. Bulk crystals have been grown from the optimized pH value of 3-4. The powder XRD analysis carried out on the grown crystals indicate no variation in lattice parameter values for different pH values of the growth solution. The FTIR analysis confirms the presence of sulfur to cadmium bonds in the complex for the crystals grown at different pH values of the solution. The functional groups present in the crystals were confirmed by Raman spectral studies. The mechanical property of the crystal grown at optimized pH was studied using Vicker's microhardness method. The change in the crystal morphology at pH values 3-4, 4-5 and 5-6 was attributed to the growth rate variations of prismatic planes at different pH values of the growth solution. Crystals grown at an optimized pH value (3-4) possess higher optical transmittance. The second harmonic generation conversion efficiency was measured qualitatively using Nd:YAG laser.