Interfacial structure of annealed alumina-zirconia-silicate nanoceramics

An alumina-zirconia nanocomposite has been produced using the chloride sol-gel method and embedded into a silicate matrix by dispersing the nanocomposite into a powdered silica glass and subsequent annealing. The resultant nanoceramic was subjected to ²⁷Al magic angle spinning (MAS) NMR, small angle X-ray scattering (SAXS), and X-ray photoelectron spectroscopy (XPS), leading to a core-shell type model of the interfacial region. Initially the particles are agglomerated with the shell containing mainly atoms of octahedral coordination and the core aluminium atoms of tetrahedral coordination. Upon annealing the agglomerates break up, causing a change in the coordination of the aluminium atoms. As the atoms diffuse into the matrix, the ones that were initially in the shell change to be tetrahedrally coordinated, and therefore increase the overall population of tetrahedrally coordinated aluminium atoms within the interface.