Knowledge Bank

Reduction of metal oxide metaphosphate glasses $(M2O\cdot P2O5,orMO\cdot P2O5$, where M is a metal cation) is observed above ca. $100\circ$C. when the glass is treated with one of several reducing agents such as $H2$, atomic hydrogen, Hg, or K, or when the material is irradiated by an electron beam. Such amorphous systems are characterized by rapid cation diffusion with cation reduction occurring principally at the glass surface, which leads to metal cluster formation and eventual continuous metal film growth. Far IR active cation motion vibrations have been observed during the course of the reaction, and measured vibrational frequencies have been related to ion diffusion properties of the bulk glass. Structural changes induced in the glass by cation migration and subsequent reduction are studied by means of transmission IR spectroscopy on thin film samples during the course of the reaction, and by reflectance techniques on bulk samples. The kinetics of the $HgO\cdot P2O5+H2$ reaction were obtained by continuous IR measurements and will be discussed.