High-Pressure and High-Temperature Behaviour of Gallium Oxide

High-temperature and high-pressure behaviours of β-Ga 2 O 3 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-Ga 2 O 3 to the trigonal α-Ga 2 O 3 occurs at around 19.2 GPa under cold compression. By heating the powder to 2000K at 30 GPa, we confirm that α-Ga 2 O 3 is the most stable structure at the high pressure. Furthermore, the structural transition from β-Ga 2 O 3 α-Ga 2 O 3 is irreversible. After laser heating, the recrystallized Ga 2 O 3 has a preferable (012) orientation. This interesting behaviour is also discussed.