Effect of aliovalent cation doping ion the electrical conductivity of Na2SO4:: Role of charge and size of the dopant

A systematic study of the effect of size of the dopant and vacancy concentration on the electrical conductivity of Na2SO4 is reported. The enhancement of conductivity, most pronounced with trivalent cation doping, and maximized for 4 m/o Sm-2(SO4)(3), is more than three orders of magnitude at 200 degrees C. The enhancement of conductivity depends on the extent of solid solubility, formation of intermediate compounds, and extent of vacancy-ion interaction. The size of the dopant influences the conductivity significantly. The effect of doping several cations simultaneously in Na2SO4 is also investigated, (C) 1998 Academic Press.