Sintering of Core-Shell Ag/Glass Nanoparticles Resulted in a Highly Conducting Metal/Glass/Ceramic Composite

Composites have attracted tremendous interest for a long time, due to their unique properties arising from the combination of totally different materials on a small scale, e.g. metals in an insulating matrix. A crucial factor of composite synthesis is the homogenous mixture of the corresponding materials without having phase separation during the process. The presented contribution solves this problem by a bottom up approach, more precisely by pressing and sintering silver-core/ silica glass-shell nanoparticles synthesized by flame spray synthesis. Compared to other, non-flame synthesis methods leading to core-shell structures, the presented method is more rapid and the glassy matrix can easily be modified. This allowed the preparation of silver/glass/ceramic composite structures with distinct glassy shells, e.g. SiO₂, Ca_xSiO_(2+x), strongly differing in their glass transition temperature. The composites had a fully homogenous appearance and exhibited an electrical conductivity comparable to a metal. Scanning electron micrographs showed clearly the formation of a highly conductive percolated silver network embedded in a ceramic matrix, which was initiated at the glass transition temperature of the glassy nanoparticle shell. References: Sintering of core-shell Ag/glass nanoparticles: Metal percolation at the glass transition temperature yields metal/glass/ceramic composites, A.C.C. Rotzetter, N.A. Luechinger, E.K. Athanassiou, D. Mohn, F.M. Koehler and R.N. Grass (submitted).