Anomalous Behavior of Glassy GeO2 in the Reduction Process by Hydrogen

The reaction of GeO2 glass with hydrogen was studied with special attention to the initial process under different conditions and the results were compared with those of crystalline GeO2. The reaction curves for the crystalline materials were a simple type which is commonly encountered in solid state reactions, whereas the curves for glassy materials at reaction temperatures above 400°C showed complicated behavior which is characterized by the presence of two steps in a reaction course. It seemed that this behavior could be understood in terms of the structural changes of the reactant involving glass transition and crystallization which are caused by the progress of the reaction. On the other hand, in the case of the reaction below 400°C, no special abnormalities were observed during the reaction.