Effect of Composition and Temperature on Volatilization of Cs from Borosilicate Glasses

Volatility of Cs from borosilicate glasses incorporated with different additives like ZnO, BaO, and CaO have been investigated as a function of heating temperatures (900 degrees C, 950 degrees C, and 1000 degrees C) and time. According to the lower Cs volatility, the sequence of the incorporated oxides is arrived as ZnO < B2O3 < BaO < CaO. It is confirmed that the volatilization of Cs occurred predominantly through diffusion controlled process. From the temperature-dependence volatility profiles of Cs, the activation energy and frequency factor was calculated and found to be in the range of 300-500 kJ/mol and 10(3)-10(12) cm(2)/s, lowest for ZnO and highest for CaO containing glasses. It was found that the frequency factor and not the activation energy were controlling the Cs loss. The observed variations in the activation energy and frequency factor have been explained by a unique model structure and possible interactions of Cs with different structural units formed due to incorporation of the different additives.