From nanoscale heterogeneities to nanolites: cation clustering in glasses

The structural behavior of cations in multicomponent oxide glasses cannot be described within a random network model, due to the presence cation clusters that provide original properties. These clustering processes are even observed for may occur at percent level concentration, which makes it all more spectacular. In particular, and chemical characteristics Zr 4+ - Fe 2+ /Fe 3+ -based (alumino)silicate illustrate link between short-range order around formation nanoscale heterogeneities. these Zr- or Fe-rich similar, as both based on edge-sharing polyhedra. Cations also network-forming position. case, sites corner-linked with silicate network. such positioning, Pauling rules local charge balance requirements will favor diluted nanoscale. topological constraints two types structure stronger former than latter, disorder effects smaller corner-sharing This explain crystal nucleation during growth ordered heterogeneities, giving rise properties illustrated large diversity glassy materials encompassing high-tech glass-ceramics volcanic glasses.