ISOMORPHOUS SUBSTITUTION OF FE IN SODALITE AND ITS ELECTRIC CHARACTERIZATION

Experiment on isomorphous substitution of Al by Fe in sodalite framewo rk was carried out using dry way method at 800-900-degrees-C in nitrog en atmosphere. The substitution of Fe was possible up to 25 mole% with some deviation of symmetry in sodalite cage. The cubic unit cell para meter increased with increasing Fe content. It showed ionic semiconduc ting property, especially the highest conductivity and the lowest acti vation energy in 10 mole% Fe-substituted sodalite which could behave a s a superionic conductor at above 400-degrees-C. When more Fe was intr oduced into sodalite the electronic conductivity was improved at high temperature. But the relative electronic contribution was found to be lower compared with ionic contribution at high temperature. In infrare d spectra some major absorption bands of sodalite shifted to lower wav e numbers due to heavier Fe atoms substitution in Al lattice sites.