La10W22O81–SiO2 and La10W22O81–WO3 Composites: Morphology and Thermal and Electrical Transport Properties

Abstract

Composites based on La₁₀W₂₂O₈₁ with highly dispersed additives of the insulator SiO₂ and the electronic conductor WO₃ have been synthesized through a ceramic route. Their morphology, thermal properties, and electrical transport characteristics have been studied. X-ray diffraction confirmed the two-phase nature of the composites. Using EMF and the dependence of electrical conductivity on the partial pressure of oxygen, it has been established that, despite the different electrical properties of the dispersed additives, oxygen ions serve as charge carriers in the La₁₀W₂₂O₈₁–WO₃ and La₁₀W₂₂O₈₁–SiO₂ composites, and the electrical conductivity of the studied composites is more than tenfold higher than that of the La₁₀W₂₂O₈₁ matrix. Based on an analysis of the morphology of the composites and the concentration dependences of their electrical conductivity, there have been proposed models of their structure that adequately explain the increase in ionic conductivity of the composites compared to the conductivity of the matrix.