PREPARATION OF NEW ION CONDUCTING MATERIALS FOR THE F-ION IN THE TERNARY-SYSTEM PBF2-INF3-BIF3 - CORRELATIONS BETWEEN ELECTRICAL-PROPERTIES AND SHORT-RANGE ORDER

A large range of solid solutions with fluorite-type structure is isolated within the PbF2-InF3-BiF3 ternary system. The investigation of electrical properties of the Pb1-xInx(1-z)BixzF2+x compositions as a function of x, at fixed z, shows that the materials of best performance are characterized by the presence of clusters of similar size and involving (n = 2) substitutional cations. The ionic conductivity variation is so studied on some series of materials characterized by clusters of the same n dimension and corresponding to the Pb1-xn-yInxn-yBi2yF2+xn+y (0 less-than-or-equal-to y less-than-or-equal-to x(n)) formulation. The dependence of electrical properties with y, at fixed x(n), shows a maximum of conductivity when the Bi/In ratio is equal to 1/2. The results are discussed as a function of the nature, number, and disorder of clusters.