Structural, Spectroscopic, Thermal and SHG Efficiency Studies of L-Phenylalanine Doped KDP Crystals 1

Abstract

Crystal growth is an important branch of solid state physics and material science. The Growth of Nonlinear Optical (NLO) materials crystals receives much importance nowadays because NLO materials have various applications in modern technologies like Laser technology, optoelectronics, and fiber optics, etc. Potassium dihydrogen phosphate (KDP) is a well known nonlinear optical (NLO) material with different applications. Since most of the amino acids exhibit NLO property, it is of interest to dope them in KDP. In the present study, amino acid L-Phenylalanine doped KDP crystals have been grown by slow evaporation solution growth technique. In present study powder XRD analysis was carried out which show that pure and L-Phenylalanine doped KDP crystals have tetragonal symmetry. The doping of L-Phenylalanine was confirmed by FT-IR and paper chromatography. Thermal analysis has been performed on the grown crystals.The SHG efficiency of L-Phenylalanine doped KDP crystals was found to be increasing with a doping concentration of L-Phenylalanine. Introduction. The demand for high quality large size KDP single crystal increases due to its application as frequency conversion crystal in inertial confinement fusion [1, 2]. KDP belongs to scalenohedral (twelve faced) class of tetragonal crystal system [3]. With the aim of improving the second harmonic generation (SHG) efficiency of KDP, researchers have attempted to modify KDP crystals by doping different types of impurities. The non-linear optical (NLO) and other properties of the crystal have been improved by doping of organic impurities [4-9]. KDP doped with amino acids like L-glutamine acid, L-gistidine, and L-valine was reported [10]. Kumaresan et al. [11] has reported the thermal dielectric properties of amino acids such as L-glutamic acid, L-histidine and L-valine doped KDP crystals. They found improved NLO properties of the KDP crystal and modifications in the structural, optical, mechanical, and electrical properties, too. Parikh [12] has reported the SHG efficiency of L-arginine doped KDP crystal. Kumaresan et al. [13] has also reported the effect of metal ion and amino acid doping on the optical properties of KDP crystal. Muley et al. [5] has studied thermal, NLO properties of KDP crystal doped with L-arginine and L-alanine. Suresh Kumar and Rajendrababu [6] studied the effects of L-arginine, L-histidine and glycine on the growth of KDP single crystals and observed that addition of amino acid enhances transparency, thermal stability and NLO efficiency of KDP crystals. Amino acid family crystals are playing an important role in the field of non-linear optical organic molecular crystal. Among them L-Phenylalanine (LPA) with chemical formula (C6H5CH2CH(NH2)COOH) is the α-amino acid with a non-reactive hydrophobic benzyl side chain. The physical, chemical and non-linear optical properties of KDP are enhanced by adding optically active amino acids as dopants.The growth and characterization of Single crystals of KDP doped with amino acids namely glycine, arginine, alanine, tryptophan, histidine have been reported earlier [5-8]. In the present work, single crystals of Potassium dihydrogen phosphate (KDP) added