PROTON CONDUCTION IN NITRATE-BASED OXIDES AND RELATED CERAMICS AT INTERMEDIATE TEMPERATURES

The ionic conductivity and the Crystal structure have been studied for two types of nitrate-based oxides and related ceramics. These materia ls are mainly proton conductors at intermediate temperatures, i.e. at 300 to 600-degrees-C. For type I samples, face centered cubic structur es, with lattice parameters 8.545 +/- 0.005 and 8.903 +/- 0.005 angstr om, were observed for RbNO3 and CsNO3-based samples. The type I sample s have kept more or less the nitrate structures. For the type II sampl es, which are aluminium oxide-based ceramics, cubic structural charact eristics were observed indicating a spinel structure. Ionic and proton conducting properties were investigated using complex impedance spect roscopy, and dc conductivity measurements of concentration cells and f uel cells. The highest proton conductivity for temperatures above 400- degrees-C, 10(-2) to 10(-1) S/cm, was obtained in RbNO3 and CsNO3-base d materials. Solid state fuel cells using these materials as electroly tes have been constructed.