Thermal expansion of mixedhyphen;alkali silicate glasses

摘要

Thermalhyphen;expansion measurements were made for five varieties of mixedhyphen;alkali silicate glasses (Nahyphen;K, Nahyphen;Rb, Nahyphen;Cs, Khyphen;Rb, and Khyphen;Cs), with special emphasis on the Nahyphen;K silicates. Negative deviations from additivity were observed in the glass transformation temperature in every case, with the deviations increasing with total alkalihyphen;oxide concentration. Positive deviations from additivity were noted in the thermalhyphen;expansion coefficients in all but one case (Nahyphen;Cs), where a small negative deviation was observed. The deviations in both properties were maximized when the radius ratio of the two alkali ions was approximately 1.4, i.e., for the Nahyphen;K glasses. These results are quite similar to those reported for mixedhyphen;alkali germanate glasses which suggests that they are due to ionhyphen;ion interactions rather than to gross alterations of the glass network.