Journal of Minerals & Materials Characterization & Engineering , Vol. 10, No.12, pp.1131-1139, 2011 jmmce.org Printed in the USA. All rights reserved 1131 Growth, Optical, Mechanical and Dielectric Properties of Glycine Zinc Chloride NLO Single Crystals S. Suresh and D. Arivuoli* Crystal Growth Centre, Anna University, Chennai-600 025, India. *Corresponding author: arivuoli@gmail.com ABSTRACT Single crystals of Glycine Zinc Chloride (GZC) were grown from aqueous solution by slow evaporation technique. Single crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic system with the space group Pna2 1. The optical transmission study reveals the transparency of the crystal in the entire visible region and the cut off wavelength has been found to be 230 nm. The optical band gap is found to be 3.40eV. The transmittance of GZC crystal has been used to calculate the refractive index (n), the extinction coefficient (K) and the real  r and imaginary  i components of the dielectric constant. Mechanical studies were carried out on the as grown crystal. Dielectric constant and dielectric loss measurements were carried out at different temperatures and frequencies. Photoconductivity measurements carried out on the grown crystal reveal the negative photoconducting nature. Key words: Solution growth, Single crystal XRD, Optical transmission, Dielectric constant and loss, Photoconductivity. 1. INTRODUCTION In recent years, there has been extensive investigation on the synthesis of nonlinear optical (NLO) materials because nonlinear optical processes are technologically the basic tools of optoelectronic and photonic applications [1]. The development of highly efficient nonlinear optical materials for optoelectronic applications such as high speed information processing, optical communications and optical data storage have been the subject of intense research activity throughout the world over the past two decades [2–3]. Organic materials show a good efficiency of second harmonic generation. But most of the organic NLO crystals have poor mechanical and thermal stability. In order to increase the mechanical strength and thermal stability, organic compounds are added with inorganic compounds. Glycine is the simplest form of amino acid which reacts with other inorganic compounds to give a good mechanical and thermal stability. Amino acids are interesting organic materials for NLO applications as