Sintering of core-shell Ag/glass nanoparticles: metal percolation at the glass transition temperature yields metal/glass/ceramic composites

In order to investigate the sintering evolution of core/shell metal/glass nanoparticles, two model compounds were synthesized and their structural evolution was investigated. Silica glass coated Ag nanoparticles were synthesized by flame spray pyrolysis, pressed into bulk pills and subsequently sintered at different temperatures finally resulting in composites with a highly conductive percolated silver network embedded in a ceramic matrix. By synthesizing two glass silver nanocomposites differing in their glass composition and corresponding glass transition temperature, the direct influence of the glass matrix on the percolation network formation and the conductive properties could be investigated. The analysis of the two systems by X-ray diffraction, scanning and transmission electron microscopy and by energy-dispersive X-ray detection clearly showed that the formation of the percolated network is initiated at the glass transition temperature of the matrix.