Effects of Sn substitution on the microstructural and electromagnetic properties of MnZn ferrite for high-frequency applications

To achieve compact and lightweight power conversion devices, magnetic core materials such as MnZn ferrite are highly desired with low core losses at high frequencies above megahertz. In this work, high-valent Sn4+ ions were doped into MnZn ferrite to manipulate the electromagnetic properties and suppress the high-frequency core losses. The distribution of Sn4+ in MnZn ferrite was investigated by transmission electron microscopy with energy dispersive x-ray analysis, which indicated that most of the substituted Sn4+ ions remained at the grain boundaries rather than dissolving into the lattice, and thus greatly impacted the electromagnetic properties of MnZn ferrite. The initial permeability and saturation induction decreased monotonically with the Sn substitution. The core loss was reduced to 457 kW m−3 at 3 MHz, 30 mT, and 25 °C when the Sn substitution content was 0.003, due to the effective suppression of eddy current loss and residual loss. The sample with a Sn content of 0.003 exhibited excellent overall electromagnetic properties, which could be potentially useful in high-frequency transformers, converters, and power sources.