Pressure effects on glass and melt structure
In several recent and ongoing collaborative studies, we have studied the structures of aluminosilicate glasses quenched from melts at pressures up to 10 to 12 GPa in multi-anvil apparatus in labs at Caltech (with Paul Asimow and Jed Mosenfelder) and the Bayreuth Geoinstitut (with Dan Frost and others). We have been able to record large and systematic effects of pressure and composition on key structural variables such as Al, Si, and Na coordination, bond angle compression, etc., which are well correlated with measured, recovered density increases. We are working on more fully evaluating the effects of temperature at high pressure, and of relaxation of the structure during decompression, as well as developing simple models of the thermodynamic consequences of observed structural changes (e.g. on melt density).