Structure and mechanical properties of pyrope (Mg3Al2Si3O12) glass: Effect of high pressure

The effect of high pressure and/or high temperature on the structure and mechanical properties of pyrope glass (Mg3Al2Si3O12) was investigated. The local structure of the glass was characterized by the total pair distribution functions derived from synchrotron X-ray diffraction. The short-range order of the Si-O and Al-O pairs was not affected by densificationat 8 Gpa at room temperature. Small irreversible changes were observed in the intermediate range order of the glass, reflected in increasing density from 2.74 to 2.78 g/cm(3), hardness from 8.1 to 8.7 GPa, and elastic modulus from 86 to 99 GPa. Thermal treatment of the parent glass at atmospheric pressure induced the crystallization of forsterite and cordierite, while thermal treatment in situ at 8 Gpa induced the crystallization of the cubic phase of pyrope, with density of 3.54 g/cm(3), hardness of 16.4 Gpa, and elastic modulus of 195 GPa. This study helps to understand the effect of high pressure on geologically important materials and provides valuable insights for designing and manufacturing new glass-ceramics containing metastable phases with improved properties.