Growth and characterization of chloro bis thiourea mercury (II) chloride (CBTMC) grown by slow evaporation technique for nonlinear optical applications

Abstract

A noncentrosymmetric hard anisotropy crystals of Chloro bis thiourea mercury (II) chloride (CBTMC),[HgCl [CS(NH2)2 ]2Cl], was synthesized using water as solvent and grown by slow solvent evaporation method and its properties are reported for the first time to attest its suitability in nonlinear optical applications. CBTMC single crystals possessing good morphology with size up to 0.6 × 0.4 × 0.2 cm3 were collected from the crystallization vessels after 12 days. Crystallography structure diffraction analysis using X-radiation confirms the non-centrosymmetric (polar) space group Pmmn , which is the key requirement to exhibit nonlinear optical activity. The crystals are analyzed by powder X-ray diffraction (PXRD) to assess the good crystalline nature. The existence of various functional groups in the synthesized compound were manifested and examined by FTIR spectrum. The thermal analysis disclosed the maximum temperature of operation of 253 °C for CBTMC. The EDAX spectrum emphasized the presence of mercuric chloride in the metal complex. CBTMC crystal was subjected to SEM analysis and it divulged the surface topographies. The UV-Visible spectra revealed the absorption edge down to near UV absorption wavelength at 213 nm, which is a deciding property for SHG. From the UV absorption data optical direct band gap is assessed (Eg = 4.62 eV). The powder visible SHG response was judged by Kurtz-Perry method using a fundamental pulsed Nd: YAG laser radiation (k = 1064 nm) and SHG efficiency was determined to be 0.736 times that of KDP, moreover KDP is phase-matchable.