Investigations of the electrical, optical and mechanical properties of alkali halide doped triglycine sulphate single crystals

Abstract

Triglycine sulphate (TGS) single crystals have vest demand as an interesting material both for academic research and industrial applications. In the present research, an attempt has been made to grow TGS crystal in pure form and to study the effect of KCl as impurities on various properties of TGS single crystals. In this thesis work, pure and (0.2, 0.4, 0.6, 1 mol %) KCl doped TGS single crystals were grown by natural evaporation method from aqueous saturated solutions. The presence of various functional groups in the grown crystal is identified from Fourier transform infrared (FTIR) spectrum analysis in the wavenumber region 4000 – 400 cm-1. Lattice parameters were estimated by powder X-ray diffraction method. Optical characterization has been done by recording the UV-Vis (both absorption and transmittance) spectra in the wavelength range of 190 nm to 1100 nm. Etching studies of (001) oriented pure and KCl doped TGS single crystals were carried out using pure distilled water as an etchant at room temperature for 10s. The thermal behavior has been investigated by thermogravimetric (TGA) and differential thermal analysis (DTA) from room temperature to 600 °C. DC electrical conductivities were measured in the temperature range of 35 °C to 100 °C. Dielectric constant was measured by the parallel plate capacitor method using LCR meter in the frequency range (1- 400) kHz. The microhardness measurements were carried out by Vickers microhardness tester. The grown crystals were found to be stable, transparent, and colorless. The etch pits changed by varying the doping concentration. The UV cut off of all crystals are found to be 240 nm. The TGA and DTA show that the grown crystals are thermally stable up to about 232 °C. The DC electrical conductivity is found to increase with the increase in temperature and doping concentration. The value of dielectric constant decreases with the frequency increases and also increases with the increase of doping concentration. Firstly, hardness is increased for 0.2 mol % KCl doped TGS crystals and than it decreases with the increase of more concentration level. The hardness also high upto 50 g loads and then decreases with the increase of load.