High-pressure behavior of Β -Ga2 O3 nanocrystals

Abstract

Freestanding nanocrystalline Β -Ga2 O3 particles with an average grain size of 14 nm prepared by chemical method was investigated by angle-dispersive synchrotron x-ray diffraction in diamond-anvil cell up to 64.9 GPa at ambient temperature. The evolution of x-ray diffraction patterns indicated that nanocrystalline monoclinic Β -Ga2 O 3 underwent a phase transition to rhombohedral α -Ga 2 O3. It was found that Β- to α -Ga2 O3 transition began at about 13.6-16.4 GPa, and extended up to 39.2 GPa. At the highest pressure used, only α -Ga2 O3 was present, which remained after pressure release. A Birch-Murnaghan fit to the P-V data yielded a zero-pressure bulk modulus at fixed B 0′ =4: B0 =228 (9) GPa and B0 =333 (19) GPa for Β -Ga2 O3 and α -Ga2 O 3 phases, respectively. We compared our results with bulk Β -Ga2 O3, and concluded that the phase-transition pressure and bulk modulus of nanocrystalline Β -Ga2 O3 are higher than those of bulk counterpart. © 2010 American Institute of Physics.