The Influence of Synthesis Parameters and Heat Effect on Magnetic Properties of Powder System FexOy - BaTiO3

Powder mixture of 60 mass % of iron (Fe) and 40 mass % of barium titanate (BaTiO3) has been activated in planetary mill for 100, 120, 150, 180, 210 and 240 min in the air. During the activation the iron powder transits into iron oxides FeO, Fe2O3 and Fe3O4. Depending on the activation time the percentage of iron oxides varies. Simultaneously, with the content change of the activated system, magnetic properties change as well. The thermomagnetic measurements in the temperature interval from 200C up to 6200C have shown that the powder activated for 120 minutes exhibits maximum magnetization prior to annealing. After multiple annealings of the same sample it has been shown that the maximum magnetization of the cooled sample is obtained upon annealing at 5600C during 10 min for all activation times of as-cast powder sample. The sample obtained from pressed powder mixture activated for 120 min has the maximum magnetization, upon isothermal sintering of samples at 12000C during 2h, being M = 2,9 Am2/kg. With additional annealing of the same sample up to Curie temperature (TC = 4300C) and subsequent cooling of the sample in the magnetic field of H = 20 kA/m, the sample is permanently magnetized. The magnetization of sample cooled in the magnetic field with intensity of 20 kA/m being M = 10,15 Am2/kg