Crystal Research

An organic nonlinear optical crystal of Cesium Sulfamate crystal has been synthesised and grown by the slow evaporation solution growth method. Single crystals of optical quality were obtained by slow evaporation technique. The grown crystals were characterised by powder XRD, UV-visible spectroscopy, DTA analysis and SHG measurement test. The SHG efficiency of crystal is greater than urea and transmittance cut off wavelength is 424nm. Hyperpolarizability analysis of Cesium Sulfamate were performed with the help of Density Functional Theory (DFT) calculations using Gaussian 03 software.

Different isothermal EOS, which expresses volume ratio as a function of pressure for materials at given temperature has been discussed. During our computational investigation it is observed that Holzapfel EOS does not satisfy the agreement of as calculated by using Brennan Stacey EOS, Shanker EOS, and Vinet EOS. The critical test of EOS for solids under extreme compressions has been discussed by evaluating the pressure and volume derivative properties viz. isothermal bulk modulus and its pressure derivative, according to the data calculated for NaCl up to extremely high pressure. Among the four EOS viz Holzapfel EOS, Brennan Stacey EOS, Shanker EOS, and Vinet EOS, it is found that, Holzapfel EOS is not suitable for calculating higher pressure derivative of isothermal bulk modulus under extreme compression

The Pressure-Volume-temperature(P-V-T) relation using non inverted equation of state (EOS) viz. Murnaghan EOS, Usual-Tait EOS, Vinet EOS, Born-Mayer EOS, Birch EOS, Kumar EOS, Shanker EOS, Brennan Stacey EOS, Poirier- Tarantola EOS, Universal EOS and Freund & Ingalls EOS for NaCl-CsCl type crystals has been studied. It is found that except Murnaghan EOS, Brennan-Stacey EOS and Poirier Tarantola EOS all other EOS gives close agreement with each other even at high compression ranges. Also another remarkable characteristic observed when the value of compression decreases from 0.5 the variation in value of pressure as calculated by different EOS increases.

Amino acids exhibit excellent nonlinear optical and electro optical properties. L-alanine magnesium chloride belongs to the amino acid group and has been grown by the slow evaporation solution growth technique (SEST) at room temperature. The grown crystals have been characterized by UV-vis-NIR spectroscopy; powder X-ray diffraction and Fourier transform infrared (FTIR) Spectroscopy. Second harmonic generation (SHG) efficiency of the grown crystal has been measured by Kurtz perry powder technique. The SHG efficiency of LAMC is found to be 0.3 times that of potassium dihydrogen orthophosphate (KDP).