Hydrogen diffusion in silicate glasses

Abstract The permeation of hydrogen into silver-doped glasses in the range 280–450°C is derived from spectrophotometric determinations of the rate of precipitation of colloidal silver. By measuring this rate as a function of hydrogen partial pressure the effect of the mobility of the silver ions may be allowed for and values obtained for the alkali ion-silver ion interdiffusion coefficient. The method is tested by adding various amounts of silver to the same base glass and comparing the values obtained for P H 2 and D Ag + . When Na + is replaced by Ca ++ in simple silicate glasses the hydrogen permeation rate is reduced in spite of the decrease in the number of network modifying ions. Substitution of Mg ++ for Ca ++ leads to an increase in the permeability while replacement of Ca ++ by Sr ++ or Ba ++ causes a decrease.