A new approach to the synthesis of cobalt modified iron oxide

The new approach to the synthesis of cobalt modified iron oxide with an autoclave in a hydrogen atmospher is reported. The acicular particles of magnetite used for this technique are the following three kinds: (1) The magnetite made by usual preparation method. (2) The magnetite made from goethite whose surface was treated with SiO2. (3) The magnetite obtained by annealing of the magnetite in (2). The product has a black acicular crystalline structure. The analysis of magnetic measurements proved that the surface localization of cobalt compounds is very important in order to improve the magnetic stability.