Temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites

TL;DR

This study investigates how cobalt substitution affects the temperature-dependent core loss in Ni-Zn-Cu ferrites, revealing a significant reduction in core loss near anisotropy compensation temperature, leading to improved ferrite performance.

Contribution

It demonstrates that cobalt substitution can significantly reduce core loss in Ni-Zn-Cu ferrites by exploiting anisotropy compensation effects, achieving a fourfold improvement over existing materials.

Findings

Core loss exhibits a minimum near anisotropy compensation temperature.

Cobalt substitution enables a fourfold reduction in core loss.

Developed ferrite has a core loss of 350 mW/cm³ at 80°C, 1.5 MHz, 25 mT.

Abstract

The temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead to a compensation of the magneto-crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on the cobalt content and the Ni/Zn ratio. We observed similar behaviour in Ni-Zn-Cu and it was found that the core loss goes through a minimum around this magneto-crystalline anisotropy compensation. Moreover, the anisotropy induced by the cobalt allowed a strong decrease of core loss, a ferrite having a core loss of 350 mW/cm3 at 80 ^\circ C was then developed (measured at 1.5 MHz and 25 mT). This result represents an improvement of a factor 4 compared to the state of art Ni-Zn ferrites.