Bulk Modulus and Young's Modulus of Nanocrystalline γ‐Alumina

Compression measurements were performed for the first time on nanocrystalline γ‐alumina utilizing a diamond anvil cell (DAC) and the energy dispersive X‐ray diffraction method. The cubic unit cell ( a = 0.7924 nm) for γ‐alumina was found to have a volume compression of about 2.4% over the pressure range from ambient to 3.8 GPa at room temperature under both hydrostatic and nonhydrostatic conditions. Using the first‐order Bridgman equation and the Birch equation of state, the isothermal bulk modulus ( B 0 ) was determined to be 162 ± 14 GPa and Young's modulus ( E ) was estimated to be 253 ± 22 GPa assuming a Poisson's ratio for γ‐alumina of 0.24 ± 0.2.