Behavior of the glass transition and crystallization temperatures of the oxide glass MgO-Al2O3-SiO2 under external influences

The kinetics of the glass transition T-g and crystallization T-cr temperatures of the glass MgO-Al2O3-SiO2 is studied under conditions of annealing in the glass transition interval and after treatment with a pulsed magnetic field (PMF). It is found that all the parameters studied exhibit nonmonotonic and intercorrelated variations in time. These temporal variations are due to structural relaxation (SR) in the glass. It is observed that a relative decrease of T-g and T-cr occurs in the annealed or PMF-treated glass. This effect is important from the standpoint of modern ideas about the mechanisms of structural relaxation and is due to the concentrational redistribution of chemical bonds. The condition for externally induced anomalous behavior of the temperatures investigated is determined. (C) 1997 American Institute of Physics.