Effects of grain size on the residual loss of Mn–Zn ferrites

Abstract

The effect of grain sizes on the electromagnetic properties of Mn–Zn ferrites has been studied up to MHz range. The average grain sizes ranging between 2 and 5 μm were obtained by varying the sintering time from 2 to 12 h. The total power loss at 1 MHz, 25 mT, and 100 °C increased with grain size. The hysteresis loss decreased with increasing grain size, while the eddy current loss and the residual loss increased. The residual loss showed a drastic increase at the grain size around 4 μm, which confirms that the residual loss due to the domain wall resonance should be taken into account at a grain size greater than the monodomain dimension.

Analysis of losses in NiO doped MnZn ferrites

“…6 displays P r of MnZn ferrites doped with different NiO contents. P r reduces gradually with increasing NiO, and at 100 • C is higher than that at 25 • C. According to Jeong et al's report [21], P r should be decreased with the decline of average grain size (D). This means that the main part of P r is actually resonance loss.…”

Development of low loss Mn–Zn ferrite working at frequency higher than 3MHz

“…As we can see, the average diameter of the grain is about 2.55 mm, which reduces the P r in high frequencies, and also makes the high peak of complex permeability. In Mn-Zn ferrite, it is reported that a transition in the intragranular domain structure from the single domain to the multiple domain state occurs at the grain size 3.870.7 mm [6,14]; it is also found that there is a drastic increase in P r at the grain size around 4 mm [15], suggesting that P r due to the domain wall resonance should be taken into account at the grain size greater than single domain dimensions. This means when the grain size is greater than the single domain dimension, P r due to domain wall relaxation process as well as the rotational resonance process should be taken into account.…”

Effect of Firing Temperature on the Electromagnetic Properties of Electronic Transformer Cores Developed by Using Nanosized Mn–Zn Ferrite Powders

“…These results reveal that cores sintered at 1,000°C started to operate when the frequency is above kHz order. It is evident that magnetic induction (low hysteresis loss) is more important than electrical resistance of ferrite cores in kHz order frequency range [25]. Mn-Zn ferrite cores with large size grains work well in kHz frequency range due to their better magnetic induction and low hysteresis losses.…”