THE INFLUENCE OF OXYGEN ON THE ELECTRICAL PROPERTIES OF CaF2 AND BaF2 SINGLE CRYSTALS

摘要

This work covers the study of the influence of oxygen on the electrical conductivity of CaF2 and BaF2 single crystals for the temperature range 450-1 200 °C. The study included three different aspects : thermogravimetry measurements, total electrical conductivity and cationic transport number. Results show that oxygen takes up substitutional positions. The reaction of introduction is accompanied by the occurrence of fluoride ion vacancies, VF, and the irreversible departure of fluorine. The study also showed how the intrinsic, extrinsic and association domains vary according to the partial pressure of oxygen.