Growth, Structural, Spectroscopic and Thermal Analyses of Novel Organic Brucinum-3, 5 –Dihydroxybenzoate Dihydrate Single Crystals for NLO Applications

Abstract

Along the line of available efficient nonlinear optical (NLO) organic single crystals in the literature, it is worthwhile to bring in a novel organic single crystal of Brucinium-3,5-dihydroxybenzoate dihydrate (B35D) which was successfully grown utilizing the technique of slow evaporation of solution at ambient conditions. As the solubility of B35D was found to be the highest in water-ethanol 1:1 mixed solvent among the conventional solvents, crystallization of B35D was accomplished by making use of the solvent. The required confirmation of the crystal structure of the crystal and its lattice parameter could be achieved by the single-crystal X-ray diffraction analysis such that B35D was found to be crystallized in the monoclinic system with the non-centrosymmetric space group C2. The recording of UV-Vis-NIR transmittance spectrum of the crystal was undertaken between the range of 300 and 900 nm whereby the lower optical cutoff wavelength was identified to be 321 nm. The spectral study of photoluminescence was carried out in the range of 300-600 nm by which the band gap energy was calculated to be about 3.8 eV (at 373 nm) indicating that B35D has a violet fluorescence spectrum. The thermal stability and melting point of the title crystal have been investigated through Thermo gravimetric and differential thermal analysis (TG-DTA) such that the thermal stability of the crystal was found to be 95.6 °C. The Nd: YAG Q-switched laser was employed so as to obtain the laser-induced surface damage threshold of the specimen which was estimated to be 3.1 GW/cm2. The Vickers microhardness test was implemented in order to arrive at the mechanical strength of the crystal. The performed non-linear optical study could reveal that the second-order harmonic generation (SHG) efficiency of B35D crystal is 2.16 times higher than KDP. So that B35D crystals are among the class of NLO materials.