Vickers Micro-Hardness Studies of Amino Acids (L-Histidine, L-Threonien and DL-Methionine) Doped KDP Crystals

Pure and various amino acids (L-histidine, L-threonine, DL-methionine) doped KDP crystals were grown by slow solvent evaporation technique. The doping of amino acids was confirmed by C, H, N analysis, FTIR spectroscopy and paper chromatography .Pure and doped KDP crystals were subjected to Vickers microhardness studies. Indentations were made on smooth (100) as grown faces of pure and doped crystals. The Vickers indenter loads were varied from 0.298 N to 0.981 N in order to study the effect of load on microhardness. A number of indents were made at each load and the mean diagonal length (d) was used in calculating the Vickers Hardness Number (HV). The Vickers micro-hardness decreased as amino acid doping level was increased indicating that the KDP crystals became softer after doping. The Indentation size effect (ISE) the Kicks law as well as PSR model was verified for all samples. The values of the load independent hardness and the Newtonian pressure (W) were higher in pure KDP crystals than the amino acids doped KDP crystals. It was found that as the doping concentration of amino acids increased the values of load independent hardness and Newtonian pressure decreased. Hays and Kendall law analysis was also applied to the hardness data.