Reduction of nickel in soda-lime-silicate glass by hydrogen

The reduction of nickel in a soda-lime-silicate glass by hydrogen was measured as a function of time at 600 degrees C. Nickel is reduced to the metallic state in a surface layer whose thickness increases with treatment time. The reduction process was followed by thickness measurements, optical spectroscopy and magnetization measurements. The layer thickness is proportional to t(1/2) but the evolutions of the optical absorbance and of the magnetization differ. This difference results from a size dependence of the optical and magnetic properties of the particles formed during the early stages of the process. The differences existing between copper and nickel doped glasses are related to the existence of monovalent copper.