High-Pressure and High-Temperature Behaviour of Gallium Oxide

High-temperature and high-pressure behaviours of β-Ga₂O₃ powder are studied by energy-dispersive x-ray diffraction in a diamond anvil cell (DAC). It is found that the phase transition from the monoclinic β-Ga₂O₃ to the trigonal α-Ga₂O₃ occurs at around 19.2GPa under cold compression. By heating the powder to 2000K at 30GPa, we confirm that α-Ga₂O₃ is the most stable structure at the high pressure. Furthermore, the structural transition from β-Ga₂O₃ to α-Ga₂O₃ is irreversible. After laser heating, the recrystallized Ga₂O₃
has a preferable (012) orientation. This interesting behaviour is also discussed.