Silver particles in glasses of the 'Ag₂O-ZnO-P₂O₅' system

Silver particles of several sizes can be dispersed in glasses of the 'Ag₂O-ZnO-P₂O₅' system. By introducing a small proportion of SiO₂ or Al₂O₃ micron-sized silver particles are obtained in low silver content glass compositions whereas nanometer-sized particles precipitate in silver rich glasses. The particle-glass composites exhibit the classical absorption plasmon band peaking about 430 nm. The thermal variation of the peak full-width at half-maximum (FWHM) as the annealing temperature of the glass increases is analyzed by the Mie theory and corresponds to an increase of the particle radii from 11 to 30 nm. In composite glasses containing micrometric silver particles, time resolved luminescence spectroscopy reveals the formation of a new emitting center (Ag₂)⁺ located in the vicinity of the silver particles and which can be considered as an intermediate step between Ag⁺-Ag⁺ pairs and silver metal in the process of silver precipitation.