A new magnetic material composed of a precipitated fine iron with spherical shape and an oxide was experimentally produced. When amorphous Fe₃O₄-CaO-SiO₂ oxides were heated in the hydrogen gas, the fine iron particles were separated from Fe₃O₄ and the magnetic properties of the sample was markedly enhanced. The present paper deals with the kinetics of reduction process as well as the ensuring variation of the magnetization and the electric resistivity.
(1) The precipitation of fine iron particles was particularly noteworthy in the sample containing a large quantity of Fe₃O₄ and a marked increase of the magnetization was followed by this reaction. The increasing temperature tended to promote the reduction.
(2) A close relation was found between the electric resistivity and the Fe₃O₄ content. When the samples with more than 60 mol% of Fe₃O₄ were heated at above 950°C, a marked decrease of resistivity was observed. Such phenomena were not detected in the samples with less than 50 mol% of that. This marked decrease may be connected with precipitated iron particles themselves.
(3) Effective permeability, μ_eff, measured on the sample with a short stick shape was 3 or 4. It may be possible to produce the sample having the excellent characteristics in both magnetization and the electric resistivity, if optimum condition for preparation could be obtained.