Growth and Thermal Studies of Doped and Pure Crystals of L-Argininium Dinitrate

Abstract

Single crystals of pure and Cu 2+ doped semiorganic L-argininium dinitrate (LADN) crystals were grown by slow solvent evaporation technique, with the vision to improve the physicochemical properties of the sample. Single crystal XRD studies of both pure and doped samples were carried out. The thermal (DTA, TGA and DSC) studies were carried out and the results are compared. IntroductionWithin the last few years, a great deal of research work has been carried out in non-linear optical materials. Both the inorganic and organic materials were investigated and it was found that the inorganic crystals were characterized by good stability and high transparency range but their second order coefficients were limited. In contrast organic crystals exhibited higher second order nonlinear coefficients but their transparency domain was reduced [1]. This triggered the search for inorganicorganic hybrid crystals. Complexes of amino acids with inorganic salts proved to be one such material with interesting non linear properties. The salt of amino acid like L-arginine phosphate monohydrate (LAP) is a more recent nonlinear optical material that has been proposed as a replacement for Potassium dihydrogen phosphate (KDP) crystal [2-4]. The structure of LAP was solved by Aoki et al [5]. In view of its encouraging non linear properties scientists tried to grow other salts of L-arginine [6][7][8][9].L-arg.HNO 3 was one among the compounds described by Monaco et al, which precipitated as a fine non-crystalline powder [6]. Interestingly, Petrosyan et al was successful in crystallizing L-arg.2HNO 3 (LADN) from solution containing Arg:HNO 3 in ratios from 2 to 10 [9]. Ramasamy et al have determined the structure of L-argininium dinitrate (space group P2 1 ) and reported that the diprotonated argininium molecule is linked by a strong hydrogen bond to the nitrate anion [10]. Recently, Terzyan et al have also solved the structure of 2(L-arg.HNO 3 ).H 2 O and L-arg.2HNO 3 [11] .Recent experiments reveal that nonlinear performance can be improved by bringing out the compositional modification and metallic substitutions [12][13]