The influence of radiation and multivalent cation additions on phase separation and crystallization of glass. 1998 annual progress report

'The major objectives of this proposed investigation are as follows: (1) To investigate the influence of multivalent cations on the thermodynamics and kinetics of phase separationand crystallization in simple model glasses. (2) To study the influence of a and b particle, heavy ion bombardment and g irradiation on phase separation and crystallization in simple model glasses. (3) To examine the structural changes produced by radiation just prior to the onset of phase separation and/or crystallization. (4) To develop models to explain the observed effects of multivalent cations and radiation on phase separation and crystallization. (5) To utilize the results of these experimental and modeling studies to provide guidelines for the allowed range of composition choices and processing conditions in order to avoid the formation of unwanted phases in nuclear waste disposal glasses. At the fundamental level, the effects of radiation, of transition metal ion additions, and of melting history in the case of multi-valent cations, on phase separation and crystallization behavior will be evaluated for simple glasses whose baseline behavior is characterized and understood. At the practical level, the program will determine the magnitude of the risk associated with the effects of radiation in inducing phase separation and crystallization. It will also provide approaches to ameliorating such effects through controlled complementary dopants and control of melting/processing conditions.