Crystallization and magnetic properties of amorphous iron–chromium oxide nanoparticles synthesized by sonochemistry

Dang Phu Nguyen, Quoc Tuan Tran, Xuan Sy Trinh, Thanh Cao Hoang, Hoang Nam Nguyen and Hoang Hai Nguyen

Abstract

Amorphous iron–chromium oxide Fe_2−xCr_xO₃ (x=0, 0.05, 0.10, 0.15, 0.20) nanoparticles were synthesized by sonochemical method at 80 °C. Crystallization process of the annealed samples showed a strong ferromagnetic behavior due to the existence of the maghemite phase. The effect of chromium replacing iron in the crystallization process of Fe_2−xCr_xO₃ nanoparticles was systematically studied by adjusting initial concentration of Cr³⁺. The activation energy of the samples deduced from thermal analysis and increased with doping chromium showed that the existence of chromium can significantly slow down the ageing effect of the amorphous iron oxide