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 SiO
2
. (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.