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 K 2 SO 4 doped with divalent ions, viz. Mg 2+ , Zn 2+ , Cu 2+ , and Mn 2+ . The presence of the divalent ion increases the cation migration energy. The lower defect formation energy is attributed to the lower symmetry of K 2 SO 4 relative to the high symmetry cubic systems previously studied.The presence of the dopants and dopant concentration, i.e. Cu 2+ , 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 K 2 SO 4 crystal doped with radioactive 65 Zn, however, exhibits a simpler linear dependence and the absence of "pretransition" anomaly.