Molecular dynamics simulations of pressure-induced structural and mechanical property changes in amorphous Al2O3

• Fraction of units AlOx and density of each AlOx type change upon compression.
• O atoms form fcc and hcp clusters with increasing pressure.
• The same units AlOx link together to form atomic clusters.
• The Young's modulus can be expressed well via the fraction of units AlOx.

Molecular dynamics (MD) simulations of amorphous alumina have been carried out to investigate the pressure-induced structural transformation and mechanical properties. We found that not only the fraction of units AlOx (x = 4, 5, 6) but also the density of each AlOx type change upon compression. The density of sample can be expressed through the fraction and partial density of units AlOx. With increasing pressure, O atoms are more ordered than Al atoms and form fcc and hcp clusters. The same units AlOx link together to form atomic clusters (AC) of type AC4, AC5 and AC6 (AC4, AC5 and AC6 consist of units AlO4, AlO5 and AlO6, respectively). The Young's modulus can also be expressed through the fraction and partial Young's modulus of units AlOx.