Synthesis and Magnetic Properties of Fe7C3 Particles with High Saturation Magnetization

The formation behavior and magnetic properties of Fe 7 C 3 particles were investigated under atmospheric pressure. The starting material of barium-containing iron oxide was carbureted with CO by heat treatment. Fe 7 C 3 particles were formed in the reaction temperature range of 300–375°C along with a small amount of Fe 5 C 2 particles. Fe 7 C 3 content in the product increased with the increase in the partial pressure of CO and the decrease in the reaction temperature. DTA-TG analysis revealed that the product contained about 5–10 wt% free carbon. The saturation magnetization of the product was about 110 emu/g regardless of the reaction conditions. The coercivity and the ratio of the residual magnetization to the saturation magnetization increased with the increase of the Fe 7 C 3 content in the product.