Structure and property of Na2O-B2O3-GeO2 glass based on Raman spectroscopy and chemical equilibrium concept
Ota Rikuo; Wakasugi Takashi; Fukunaga Jiro
Abstract:Ota and co workers determined a set of equilibrium constants which govern the number density of the structural units in alkali borate glass. Based on the results, the molar volume of the system was computed. However, this technique cannot be applied to the Na2O-B2O3-GeO2 system where the state analyses on Ge ions in the Na2O-B2O3-GeO2 system have not been fully conducted. In the present study a new method to calculate the molar volume of multi component alkali borate system is presented. Raman spectra were used to elucidate that Na2O affinity for B2O3 is stronger than that for GeO2. Assuming the relative magnitude of activity coefficient g of Na2O for B2O3 against for GeO2 tentatively 1:2, the distribution of Na2O among B2O3 and GeO2 was determined. The molar volume of the Na2O B2O3 GeO2 system was calculated from the partial molar volumes of the sub systems Na2O-B2O3 and Na2O-GeO2 in good agreement with the experimental value. Key Words:Raman spectrum, Na2-B2O3-GeO2 system, molar volume, activity coefficient