Abstract: MgO-Al₂O₃-SiO₂-TiO₂-Y₂O₃ glasses with high elastic moduli were prepared for the substrates of hard disks. The elastic moduli of glasses
change with their compositions according to Makishima-Mackenzie theory. The oxides with big dissociation energies per unit volume, such as MgO, Al₂O₃, TiO₂
and Y₂O₃, are beneficial to the elastic moduli of glasses. The elastic moduli calculated by means of Makishima-Mackenzie theory, however, are lower than the
measured data, the deviation can be attributed to the pretermission of the coordination structures of cation ions in glasses, and the packing volume factors of MgO and
Y₂O₃ are not accurately dealt with, so the calculated elastic moduli of the glasses containing MgO and Y₂O₃ should be corrected.

Key words: MgO-Al₂O₃-Si0₂-Ti0₂-Y₂O₃ glass, elastic moduli, Makishima-machenzie theory, substrates for hard disks