Vickers Microhardness Studies of Pure and Amino Acids Doped Potassium Dihydrogen Phosphate Crystals
Vickers microhardness study was carried out to understand the mechanical behaviour of pure and different amino acids (L-arginine, L-lysine, L-alanine) doped potassium dihydrogen phosphate (KDP) single crystals grown by slow solvent evaporation technique. Indentations were made on smooth {100} plane of pure and different amino acid doped crystals for loads varying from 0.298 N to 0.98 N. Vickers microhardness decreased as doping level of amino acid was increased. Indentation size effect (ISE), Kick's law, Hays and Kendall's law and Proportion specimen resistance (PSR) model were verified for pure and different amino acids doped crystals. The values of the load independent hardness and Newtonian pressure were higher in pure KDP crystals than the amino acids doped KDP crystals. It was found that as doping concentration of amino acids increased the load independent hardness and Newtonian pressure decreased. The results indicated that the doping of amino acids made KDP crystals softer.