Tailoring the Temperature Characteristics of the Magnetic Permeability of NiZn-ferrites
The effect of cobalt addition on the temperature characteristics of the magnetic permeability of NiZn ferrites was studied and a comparison to the respective behaviour of cobalt in NiCuZn ferrites was examined.Cobalt-doped NiZn and NiCuZn ferrites were manufactured by the ceramic route and sintered under various atmosphere profiles. The chemical and morphological characteristics were evaluated by X-ray diffraction (XRD),scanning electron microscopy (SEM) and thermogravimetric analysis (TGA-DSC). The evaluation of the magnetic performance of the sintered ferrites showed that reducing atmosphere profiles during the top temperature and cooling time of the sintering process favour the temperature stability of the permeability in the case of NiZn ferrites, while preserving the losses at low levels. Two mechanisms that take place at the same time are proposed:the change of the Fe2+ /Fe3+ ratio due to the reducing atmosphere in combination with an increase of the magnetocrystalline anisotropy and magnetostriction due to the reduction C03+-C02+ under N2 atmospheres suggest a useful method to tailor the temperature factor aF of NiZn ferrites. However, the method cannot be applied in NiCuZn ferrites, as the reduction Cu2+-Cu+ taking place under N2 atmospheres enhances secondary re-crystallization phenomena, causing a dramatic increase in losses.
NiZn ferrite temperature factor reducing atmosphere magnetocrystalline anisotropy
V.Tsakaloudi P.van der Valk V.Zaspalis
Center for Research and Technology-Hellas,Chemical Process Engineering Research Institute,Laboratory Ferroxcube International,p.o.Box 80058,5600KA Eindhoven,the Netherlands
国际会议
The 10th International Conference on Ferrites(2008中国国际铁氧体研讨会)
成都
英文
179-182
2008-10-10（万方平台首次上网日期，不代表论文的发表时间）