Significantly enhanced magnetism in cobalt ferrite by manganese and terbium co-doping

The structure and magnetism of cobalt ferrites after Mn2+-Tb3+ co-doping were studied. All samples have cubic spinel structure and spherical shape of ferrite nanoparticles after co-doping. Both Co2+ and Fe3+ will preferentially occupy the octahedral sites and Mn2+-Tb3+ co-doping can migrate some of them between octahedral sites and tetrahedral sites. The coercivity and magnetization saturation of Mn2+-Tb3+ co-doped samples are improved significantly and simultaneously due to the combined influence of the doped ions and the resulting cation redistribution and surface effect. Based on these, the maximum value of the maximum energy product can reach 1.0569 MG & sdot;Oe and is about 190% higher than that of un-doped one, which is undoubtedly very attractive as the maximum value mentioned in existing literature is only 118%. These results demonstrate that the codoping of manganese and terbium is highly effective in improving the magnetism of cobalt ferrite, which provides a good direction for the subsequent study of the magnetic improvement of cobalt ferrites.