Particle-size effect on the compressibility of nanocrystalline alumina

Room-temperature x-ray diffraction to 60 GPa yields zero-pressure bulk modulus values of K₆₇=238±3GPa and K₃₇=172±3GPa for nanocrystalline {γ}-alumina (Al₂O₃) with particle sizes of 67 and 37 nm, respectively. Combined with the results of previous high-pressure x-ray studies of 20 and 6 nm nanocrystalline Al₂O₃, it is found that compressibility increases with decreasing particle size. A new phase was detected at pressures above 51 and 56 GPa for γ-Al₂O₃ of 67 and 37 nm, respectively.