Effect of dispersed Al2O3 and SiO2 on the phase equilibria of NH4HSO4

Abstract

Differential scanning calorimetry (DSC), impedance spectroscopy (IS) and X ray diffraction were used to study the composite solid electrolytes (1-x)NH4HSO4-xAl2O3 (x?0.5) and (1-x)NH4HSO4-xSiO2 (x=0.3. The DSC results shows that new morphological states are formed by the Al2O3 doping because new phase boundaries are observed below the melting point of AHS in the composites. The X-ray diffraction data also confirm that the composites with alumina be-comes more amorphous as x increases reaching completion for x >= 0.3. On the other hand, the dc-conductivity is only improved on adding either Al2O3 or SiO2 to AHS in the solid phases of the composites. The results are discussed in terms of the influence of the dispersed second phase on the overall electrical response and phase behaviour of the composites