The forming region and mechanical properties of SiO2-Al2O3-MgO glasses

The glasses of 93.9% (xSiO2-yAl2O3-zMgO)-5% CaO-1% B2O3-0.1% Fe2O3 were prepared, and the relationship between mechanical properties and structural stability were characterized by means of Raman spectroscopy and optical band gap values. The glass forming region is found to be x = 50-70%, y = 10-25% and z = 15-32%. As x = 65%, y = 10% and z = 25% (SAM-4), the investigated glass possesses the optimum volume density, oxygen packing density, optical band gap, banding strength, compression strength and compression modulus, which are 2.517 g/cm3, 77.047 mol/l, 3.56 eV, 77.04 MPa, 202.74 MPa and 106.70 GPa, respectively. Meanwhile, starting from the representative point of SAM-4 to radiate around, the volume density, oxygen density, Raman intensity and mechanical properties of the glasses are all decreasing constantly, and the optical band gap of the glasses is increasing on the contrary. Moreover, the optical band gap value and Raman spectroscopy of SAM-4 all prove that the number of oxygen bonds in the bridge reach the maximum and the highest structural stability is achieved, which further shows that it is an important reason why its mechanical properties is significantly improved.