Journal of Physics and Chemistry of Solids 69 (2008) 1974–1979 Thermal, mechanical, and electronic properties of glycine-sodium nitrate crystal J. Herna´ndez-Paredes a,Ã , Daniel Glossman-Mitnik a , O. Herna´ndez-Negrete a , H. Esparza-Ponce a , M.E. Alvarez R b , R. Rodrı´guez Mijangos c , A. Duarte-Moller a,b a Centro de Investigacio´n en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes Saavedra 120, Complejo Industrial Chihuahua, Chihuahua 31109, Me´xico b Departamento de Fı´sica, Universidad de Sonora (UNISON), Blvd. Luı´s Encinas y Rosales s/n, Hermosillo, Sonora 83000, Me´xico c Departamento de Investigacio´n en Fı´sica, Universidad de Sonora, Blvd. Luı´s Encinas y Rosales s/n, Hermosillo, Sonora 83000, Me´xico Received 10 December 2007; received in revised form 9 February 2008; accepted 11 February 2008 Abstract Glycine-sodium nitrate, C 2 H 5 N 2 NaO 5 (GSN), crystals were grown from aqueous solutions by slow cooling with a temperature lowering rate of 1 1C/day in the range of 40–22 1C. These crystals were analyzed by differential thermal and thermogravimetric analysis (DTA-TGA) and mechanical hardness tester in order to obtain their thermal and mechanical properties. Mechanical characterization was done by studying the variation of microhardness with applied load. The dielectric properties of GSN were calculated by using the CASTEP code within the framework of the generalized gradient approximation (GGA). For better understanding of the optical properties of GSN, the second derivative of e 2 (E) was evaluated. DTA-TGA analysis showed that the material has a thermal stability up to 198 1C. The microhardness test was carried out for several faces of GSN crystals, and the tests revealed a load dependence to hardness. Analysis of the second derivative of e 2 (E) allowed to obtain better resolution of the electronic transitions involving the energy bands. Besides, a theoretical representation of the orbitals’ energy diagram was obtained. A discussion about the relation of structure-properties and molecular character of GSN is presented here. r 2008 Elsevier Ltd. All rights reserved. Keywords: A. Optical material; B. Crystal growth; C. Thermogravimetric analysis; C. ab initio calculations 1. Introduction The non-linear optics (NLO) field demands the devel- opment of new materials that have strong interaction with a light beam. Semi-organic compounds based on aminoa- cids mixed with inorganic complexes have been found useful for second harmonic generation (SHG), process [1–4]. The purpose is to achieve the construction of useful devices such as: frequency doublers, active optical inter- connects, and switches. These devices have great applica- tions in telecommunications and signal processing [5]. However, it is known that, due to their molecular character and the large interatomic distances some of these compounds have poor thermal and mechanical properties. Unfortunately, such materials can be unstable at high temperatures. Moreover, due to their poor mechanical properties they are not adequate for processing. For these reasons, it is very important to analyze the thermal and mechanical properties of the new materials in order to recognize them as candidates for the fabrication of optical devices and photonic applications. Computational chemistry using the density functional theory (DFT) for prediction of physical and chemical properties of new materials is widely employed nowadays. This tool offers the capability to study novel materials with a simple and inexpensive scheme, because it has proved to be effective predicting the properties of new materials with good agreement [6–8]. ARTICLE IN PRESS www.elsevier.com/locate/jpcs 0022-3697/$ - see front matter r 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpcs.2008.02.010 Ã Corresponding author. Tel.: +52 614 4391127. E-mail addresses: javier.hernandez@cimav.edu.mx (J. Herna´ndez-Paredes), daniel.glossman@cimav.edu.mx (D. Glossman-Mitnik), alberto.duarte@cimav.edu.mx (A. Duarte-Moller).