High temperature Raman scattering in Sm0.8La0.2AlO3 Compound: A relation to the phase transition in rare earth orthoaluminates

Raman spectra of molten Sm0.8La0.2AlO3 have been recorded from room temperature to 1470 K. Experimental results show that a first-order phase transition occurs at 580 K and that two phonon modes appear very unstable in the high temperature phase. Comparison with Raman data obtained on rare earth aluminate single crystals indicates that these ‘soft’ modes may be associated with a rhombohedral to cubic phase transition.