Two-stage amorphization of scandium molybdate at high pressure

Using Raman spectroscopy and X-ray diffraction we find that at high pressure amorphization of scandium molybdate occurs in two stages. Excessive broadening of molybdate internal modes arising from distortion and disordering of MoO₄ tetrahedra, together with rapid weakening of diffraction from large d-spacings and disappearance of diffraction from small d-spacings suggest gross molybdate ion disorder above 4 GPa. On the other hand, complete amorphization occurs at the significantly higher pressure of 12 GPa, where diffraction disappears completely. The amorphization is also found to be irreversible.