A study of the deformation characteristics of solution—grown mixed crystals of ammonium–potassium sulphate

Mixed crystals of ammonium sulphate (AS) and potassium sulphate (PS), [(NH4)1−xKx]2SO4 were grown by slow evaporation technique at room temperature. Mechanical characterization was done by studying the variation of microhardness with applied load on (100) faces of mixed AS–PS system for several compositions. Vickerʹs hardness numbers, Hv were found to increase primarily with increase in load and then become load independent. Meyer indices, n were found to be always greater than two showing soft material characteristics. Some hardness related parameters such as crack length, fracture toughness were also calculated and interpreted. Fracture toughness increases with higher K+ concentration.