Electrical Conductivity and Phase Transformation Studies on Pure and Doped (Mg2+, Zn2+, Cu2+, and Mn2+) Crystals of K2SO4

Abstract

Electrical conductivity measurements have been made on single crystals of undoped potassium sulfate and on single crystals of K2SO4 doped with divalent ions, viz. Mg2+, Zn2+, Cu2+, and Mn2+. The presence of the divalent ion increases the cation migration energy. The lower defect formation energy is attributed to the lower symmetry of K2SO4 relative to the high symmetry cubic systems previously studied.The presence of the dopants and dopant concentration, i.e. Cu2+, show varying effects on the magnitude and nature of the conductivity discontinuity at the orthorhombic–hexagonal phase transition temperature. The phenomenon of "pretransition", 350 to 425 °C, is observed in both pure and doped crystals. Preannealing the crystal contributes to interesting behavior on all the crystals studied. The σ–T behavior of K2SO4 crystal doped with radioactive 65Zn, however, exhibits a simpler linear dependence and the absence of "pretransition" anomaly.