EFFECTS OF ALKALINE EARTH IMPURITIES ON IONIC TRANSPORT IN CAESIUM IODIDE

The electrical conductivity of single crystals of pure and Ba2+ and Sr2+- doped CsI has been measured over the temperature range 150–550°C. In pure crystals, grown either from aqueous solution or from the melt, a single region of conduction with an activation energy of 1.37 ev is observed in the temperature range above 300°C. Comparison of the conductivity with 137Cstracer diffusion measurements indicates that the conduction is predominantly due to anion migration. In the doped crystals a region of conduction associated with impurity dissolution in the lattice is observed and an analysis of the results in this region leads to values of 1.34 ev for the enthalpy of impurity solubility and 0.67 for the energy of mobility of a cation vacancy. The energy of formation of Schottky defects in the lattice is estimated to be 2.14 ev. © 1968 Taylor & Francis Group, LLC.