Studies on mechanical properties of an organic nonlinear optical crystal

The results of Vickers microhardness measurement for different crystallographic planes of nonlinear optical crystal l-arginine acetate (LAA) have been reported. Hardness of LAA is found to be influenced by anisotropic property of the crystal. The variation in the microhardness value with load is nonlinear for all planes considered here. Kick's law, modified law proposed by Hays and Kendall fail to explain the observed variations. But the variation could be best explained by PSR model proposed by Li and Bradt. Values of work hardening index n for all the planes are found to be greater than 1.6 which indicates that LAA is a soft crystal.