Enhancement of structural stability of nanosized amorphous Fe2O3 powders by surface modification

The surface of low-dimensional solids plays a key role in their phase transition. In the present study, to enhance the structural stability of nanosized amorphous Fe2O3 powders their surfaces were modified by employing NaOH solution, which leads to an increase in both the crystallization temperature from 364 °C to 411 °C and the crystallization activation energy from 81.5 kJ/mol to 156.8 kJ/mol. The surface-modified amorphous Fe2O3 powders show an entirely different crystallization behavior as compared with the as-prepared amorphous powders. The enhanced structural stability is attributed to the increase of the amount of hydroxide groupings at the surfaces of amorphous powders, which lowers their surface energy.