DETERMINATION OF THE INFLUENCE OF THE NAF RATE ON THE CHARGE-CARRIERSPARAMETERS IN SOME FLUORIDE GLASSES CONTAINING THE NAF ALKALI FLUORIDE

The bulk impedance parameters of various fluoride glasses series conta ining a large extent in NaF rate have been determined from an analysis of ac conductivity data measured in a wide temperature range. The cha rge carriers concentration in each glass studied has been evaluated us ing the Almond-West formalism and shown to be temperature independent. Transport properties in these materials are due to a hopping mechanis m of the fraction of F- ions mobile at long range (3-5%). The variatio n of different conductivity parameters as a function of the NaF conten t has been determined. When the NaF rate increases, a conductivity dec rease is observed, due mainly to a decrease of the charge carriers mob ility.