Size effect on the pressure-induced phase transition in Lu2O3

Abstract

The impact of particle size on the pressure-induced phase transition of cubic Lu₂O₃, the heaviest rare earth sesquioxide (RE₂O₃), was examined through a collaborative experimental and theoretical investigation. The high-pressure in situ Raman measurements and ab initio theoretical calculations provide verification of the enhanced phase stability of the cubic phase from 17.3 to 27.3 GPa for bulk and nanosized Lu₂O₃, respectively. In comparison to the bulk Lu₂O₃, the cubic-monoclinic phase transition is suppressed in nano-sized Lu₂O₃. In contrast, the hexagonal Lu₂O₃ was observed to form directly from the cubic phase, with the absence of the intermediate monoclinic phase. The size-dependent structural instability and transition sequence are correlated with changes in the thermodynamics and kinetics of the phase transformations, which can be well explained by ab initio density functional theory (DFT) calculations. The surface energy of nano-sized Lu₂O₃ accounts for a large proportion of the total energy, which may play an important role in the selection of phase transition paths. These findings offer insights into the size effect on the phase transitions of RE₂O₃ and provide guidance for the fabrication of new RE₂O₃ materials with distinctive properties.