The fracture to toughness ratio (bulk modulus/shear modulus) in sodium borohydride varied from to , which shows its behavioral change from ductile to brittle on increasing the temperature. Then, ultrasonic Gruneisen ¨ parameters have been computed with the use of elastic constants in the temperature regime 100- 300K. The obtained results have been discussed in correlation with available experimental and theoretical results. | Communications in Physics, Vol. 27, No. 2 (2017), pp. 151-164 DOI: TEMPERATURE DEPENDENCE OF ELASTIC AND ULTRASONIC PROPERTIES OF SODIUM BOROHYDRIDE DEVRAJ SINGH1 , GIRIDHAR MISHRA1,† , RAJKUMAR2 AND RAJA RAM YADAV3,4 1 Department of Applied Physics, Amity School of Engineering and Technology, Bijwasan, New Delhi-110061, India 2 Department of Physics, Gurgaon Institute of Technology and Management, Gurgaon-122413, India 3 Department of Physics,University of Allahabad, Allahabad-211002, India 4 Veer Bahadur Singh Purvanchal University, Jaunpur-222003, India † E-mail: giridharmishra@ Received 10 April 2017 Accepted for publication 17 July 2017 Published 31 July 2017 Abstract. We present the temperature dependent elastic and ultrasonic properties of sodium borohydride. The second and third order elastic constants of NaBH4 have been computed in the temperature range 0-300K using Coulomb and Born-Mayer potentials. The sodium borohydride crystallizes into NaCl-type structure. The computed values of second order elastic constants have been applied to evaluate the temperature dependent mechanical properties such as bulk modulus, shear modulus, tetragonal modulus, Poisson’s ratio and Zener anisotropy factor and ultrasonic velocity to predict futuristic information about sodium borohydride. The fracture to toughness ratio (bulk modulus/shear modulus) in sodium borohydride varied from to , which shows its behavioral change from ductile to brittle on increasing the temperature. Then, ultrasonic Gr¨uneisen parameters have been computed with the use of elastic constants in the temperature regime 100300K. The obtained results have been discussed in correlation with available experimental and theoretical results. Keywords: sodium borohydride, elastic constants, mechanical properties, ultrasonic properties. Classification numbers: ; ; . I. INTRODUCTION The elastic and ultrasonic properties of solid .
