Effect of Hydrochloric Acid (HCl) on Synthesis and Anisotropic Phenomena of Triglycine Phosphate (TGP) Single Crystals

International audienceEffect of Sulphuric acid (H2SO4) addition on the growth of triglycine phosphate (TGP) crystal has been studied from the aqueous solution by slow evaporation technique. The characteristics absorption bands of pure and H2SO4 admixtured TGP crystals are confirmed by FTIR spectra. UV-visible transmittance spectra were recorded for the samples to analyze the transparency of the grown crystals. The composition of pure and doped TGP crystals have been confirmed by EDAX analysis. The dielectric constants of the crystals have been studied and result suggests that the H2SO4 is doped into TGP crystal and that the doping increases its dielectric parameters. Introduction. Investigations on semiorganic nonlinear optical (NLO) materials gain importance because of good thermal and mechanical properties with large NLO coefficients [1,2]. Among the amino acids, glycine [amino acetic acid: NH2CH2COOH] is the simplest amino acid, hence,glycine mixed semi-organic material is a fundamental building block to grow many complex crystals with improved NLO properties. Reported literature shows that glycine sodiumnitrate [3], triglycine sulphate [4] etc. crystals exhibit of some glycine based compounds like triglycine zinc chloride [5], glycine sodium nitrate [6] and triglycine selenate [7] show non-linear effects ferroelectric properties and are used as infrared detectors, transducers and piezoelectric sensors due to the large difference between the inter-molecular and intra molecular chemical bonds [5–7]. One of the hydrogen bonded ferroelectric single crystal Glycine phosphate (GPI) undergoes a continuous ferroelectric–para electric phase transition at 224.7K [8]. Subsitutional or interstitial impurities in the host lattice leads to significant changes in the properties of the pure TGS crystals [9-10]. The pyroelectric coefficient of phosphoric acid doped TGS is more than that of pure TGS and observed phase transition temperature shift [11]. Inview of this, the present investigation has been focused on the growth of semi-organic Triglycine phosphate (TGP) single crystals doped with sulphuric acid at various concentrations (0.25,0.50,0.75 and 1.0 mol %) and this doping efforts on the growth aspects, structural perfection, phase transition temperature, and optical properties were studied by conducting various characterization techniques