Electrical evaluation insights of enhanced mullite-Ag cermets

Cermets with enhanced electronic conductivity were synthesized by incorporating Ag nanoparticles into a mullite matrix. Silver nanoparticles, altogether with a ceramic optimized processing and a sintering temperature, contribute to the reduction of the surface porosity of the ceramic materials. The electrical properties of the mullite-Ag cermets were analyzed by means of the Electrochemical Impedance Spectroscopy technique between 400 and 700°C in a frequency interval of 10MHz–10 mHz. The associated electrical conduction mechanism of the cermets was accomplished with an equivalent circuit model. With 1% of silver nanoparticles incorporation in the mullite matrix, the resistivity was drastically reduced (conduction increases mainly through the grain border) likewise the activation energy. Moreover, the nanometric character of the silver particles was confirmed by SEM and their interaction on the surface of the grain boundaries of the mullite determined by XPS. Graphic abstract: [Figure not available: see fulltext.]