Expansion of initial magnetization region in BaTi1.2Co1.2Fe9O19−δ at low temperature

BaTi1.2Co1.2Fe9O19−δ hexagonal ferrite was prepared by solid state reaction method sintered at 1250 °C, and its structure was examined by XRD and SEM, its magnetic properties were measured by VSM and BH analyzer at different temperature between −60 °C and 120 °C. It was found that no power loss minimum can be observed in the power loss versus temperature data when the initial permeability reaches a peak at 60 °C. Magnetic losses analysis indicated that the hysteresis loss is very small at −60 °C. The real part of permeability μ′ is a field independent constant in H < 500 A/m at −60 °C, while μ′ shows linear field dependence in the measured field range at 60 °C. The sample shows constant μ′ with very low hysteresis loss in H < 500 A/m at −60 °C, which is consistent with the characteristic of the initial magnetization region, so conclusion is that initial magnetization region expands to high magnetic field with decreasing temperature in BaTi1.2Co1.2Fe9O19−δ hexagonal ferrite. This characteristic may serve as a new way to achieve low loss soft magnetic materials.