Preparation of chromia nanoparticles by precipitation–gelation reaction

Chromia (Cr 2O 3, chromic oxide, Eskolaite) nanoparticles were prepared by precipitation–gelation reaction in aqueous solution of Cr(NO 3) 3. The morphology of the particles was investigated at various calcination conditions. The average size of chromic oxide nanoparticles was increased in proportional to the calcination temperature. Chromic oxide nanoparticles did not form any secondary particles and showed loosely agglomerated structure consisted of weakly attached particles with each other by van der Waals and capillary adhesive forces. On account of this fact, chromic oxide nanoparticles were obtained as very soft small granular form that can be applied in various applications without using mechanical size reduction processes. Furthermore, chromic oxide nanoparticles showed the smaller size, the narrower size distribution and lower degree of agglomeration compared with those of commercial product.