Nitrided glass as a reaction medium: reduction of Ag and Cu within a phosphorus oxynitride glass matrix

Nitrogen incorporation as N3- into a phosphate glass network gives the oxynitride glass medium a reducing character. From a thermodynamic approach to the reduction phenomenon we predict with good approximation the reduction or not of various metal oxides. This property makes possible the in situ precipitation of metallic particles of Ag and Cu from the corresponding oxides, in particular in the low-melting oxynitride glass composition Li0.35Na0.35PO2.4N0.3 (T-m similar to 450 degrees C). The reduction phenomenon is defined by the temperature of reduction T-r which is not directly related to the glass transition temperature T-g. (C) 1997 Elsevier Science B.V.