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Abstract In this study, the ferrite system, Ni0.28Zn0.54Cu0.18
Fe2O3, was prepared under different sintering temperature and
adding different additives, ZrO2, Ta2O5, and Bi2O3. The purpose
of this study is to investigate the effect of additives on the
microstructure of Ni-Zn-Cu ferrite, and try to find the
relationship between microstructure and magnetic properties.
From the optical observation, the growth of duplex is sensitive
to the chemical compositions and could be effected by additive
concentrations. The SEM photographs of fractured surface show
that as the sintering temperature decreasing or additives amount
increasing the fracture mode changes from transgranular to
intergranular. This is due to the degrade of microstructure
uniformity and different strength of grain and grain boundary.
At the same time, we also find that the composition of magnetic
phase is very sensitive to sintering temperature. In this
system, the best magnetic sintering temperature is between
1025℃and 1050℃. Although liquid phase sintering is one of the
densification mechanism of powder compaction. This process could
enhance mass transportation between grain and grain, which
results to chemical homogeneity of grains. However, it is also
promotes grain growth. Since grain size of ferrite is lose-
related to magnetic properties, application of liquid phase
sintering to ferrite system, special attention has to be paid.
From the results of power loss measurement, we found the
hysteresis loss is dominate. This result is consistent with m-T
property. Another importance is that the hysteresis loss bear
the most of total power loss, it means that the energy of moving
domain wall (Magnetocrystalline anisotropy energy) is the major
contribution of total power loss, and as sintered at 1025℃,
there is the minimum anisotropy constant k, due to low
hysteresis loss. As a result that to decrease power loss the
enhancement of magnetic properties is very important for this
system.
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