Pressure-induced phase transition of B-type Y₂O₃

The synthesized monoclinic (B-type) phase of Y₂O₃ has been investigated by in situ angle-dispersive x-ray diffraction in a diamond anvil cell up to 44 GPa at room temperature. A phase transition occurs from monoclinic (B-type) to hexagonal (A-type) phase at 23.5 GPa and these two phases coexist even at the highest pressure. Parameters of isothermal equation of state are V₀=69.0(1) ų, K₀=159(3) GPa, K₀'=4 (fixed) for the B-type phase and V₀=67.8(2) ų, K₀=156(3) GPa, K₀'=4 (fixed) for the A-type phase. The structural anisotropy increases with increasing pressure for both phases.