Microhardness studies in gel-grown ADP and KDP single crystals

Microhardness studies were carried out on (100) faces of gel-grown ADP and KDP single crystals. Slip lines were observed on (100) face of ADP crystal at the corners of the impressions. Microcracks around the indentation were found on (100) face of KDP crystal from 10g load which spread out as the load increased. Vickers hardness numberH _v decreased with increase in load. ΔH _v at 50g load for solution-grown crystals and gel-grown crystals (present case) was determined. Work hardening indexn for both ADP and KDP crystals was less than 2 showing soft-material characteristics. Using Wooster’s empirical relation, values of C₁₁ from hardness were calculated and found to be close to the reported ones. The work was done under a research project sanctioned by the Council of Scientific and Industrial Research (CSIR), New Delhi.