An investigation of the thermal defect order, defect mobility, and defect complex formation in cadmium fluoride. (Ionic conduction)

Abstract

The dependence of the resistance and ionic thermal currents (ITC) and CdF2 crystals on the NaF and YF3 content, temperature, applied voltage and other factors has been investigated. It is shown that the current passing through the crystals is due to the transport of anion vacancies and fluorine interstitials, which under favourable conditions associate with the monovalent sodium and the trivalent yttrium impurity respectively. It is further shown that the observed ITC signals are due to the accumulation of charge carriers (space charge) and defect-impurity complexes at the electrodes. The energies of formation of the defect-impurity complexes and the activation energy of motion of the defects are obtained from both kinds of measurements independently and good agreement is found between the respective values. The energies of formation of the intrinsic defect pairs are also obtained from the conductivity measurements.