CoBixFe2-xO4 (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) powders were prepared via conventional ceramic method. Nano-crystalline cobalt ferrite doped bismuth and CoBixFe2-xO4–Bi2O3 (80–20 %) powders have been synthesized by ball milling route . The structural and magnetic properties of the samples were determined by X-ray diffraction, vibrating sample magnetometer and Faraday balance. X-ray analysis showed that the samples were cubic spinel. The addition of Bi3? ions caused a decrease in magnetization, Curie temperature and the coercivity of the samples. The observed decreases in saturation magnetization and coercivity are explained on the spin-glass-like surface layer on the nanocrystalline cobalt–bismuth ferrite and magnetic anisotropy, including magneto-crystalline and strain induced anisotropies during ball-milling processing; respectively. The photo catalytic behaviour of CoBixFe2-xO4–Bi2O3 nanocomposites was evaluated using the degradation of three various azo dyes under ultraviolet light irradiation. The results show that nanocomposites have applicable magnetic and photo catalytic performance.
