CONDUCTIVITY OF PBSNF(4) SOLID-ELECTROLYTE

The impedance of cells consisting of blocking electrodes and PbSnF4 fl uoride-ion-conducting solid electrolyte was investigated. At temperatu res below 20-degrees-C the components of electrolyte impedance were fo und to be determined by the superposition of geometric capacitance, gr ain-boundary impedance, and resistive impedance of the grains of polyc rystalline material. It was shown by X-ray phase analysis that dependi ng on gas-phase composition, the solid-state reaction between lead flu oride and tin fluoride yields the beta-phase, the alpha'-phase, or a m ixture of these phases of PbSnF4 as the reaction products. It was seen when determining the conductivity of the polycrystalline two-phase mi xture that the bulk conductivity of the grains is close to that of the radiographically pure beta-phase, while the grain-boundary conductivi ty is close to the conductivity of the alpha-phase. It was suggested t hat oxygen influences the phase composition of PbSnF4 at low temperatu res.