Etching, micro hardness and laser damage threshold studies of a nonlinear optical material L-valine

¹ Department of Physics, Valliammai Engineering College, SRM Nagar, Kattankulathur, Chennai 603203, India
² Centre for Material Science and Nano Devices, Department of Physics, SRM University, Kattankulathur, Chennai 603203, India
³ Department of Chemistry, Valliammai Engineering College, SRM Nagar, Kattankulathur, Chennai 603203, India
⁴ Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302, India

^a e-mail: chezhiyan70@gmail.com

Received: 11 September 2011
Revised: 7 January 2012
Accepted: 1 March 2012
Published online: 23 March 2012

Abstract

A nonlinear optical crystal of L-valine was grown from an aqueous solution containing a small amount of phosphoric acid by the slow evaporation method. The grown crystal was characterized by a single crystal X-ray diffraction to determine the unit cell parameters. The powder X-ray diffraction analysis also confirmed the lattice parameters to be a = 9.6687(7) Å, b = 5.2709(4) Å, c = 12.0371(10) Å and β = 90.805(4)°. The results of the Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES) indicate the presence of a small amount of phosphorus in the grown crystal. The Vickers micro hardness test was performed to study the mechanical strength of the crystals. Chemical etching studies were carried out to analyze the dislocation structure. The laser damaged threshold of the grown crystal was measured to be 11.11 GW/cm² for 10 ns pulse at 1064 nm, which is higher than that of the standard nonlinear optical crystals like KDP. Second harmonic generation of the grown crystals was also 1.44 times that of KDP.