Effect of chromium (Cr²⁺) additive on electrical and dielectric studies of cobalt doped cadmium–nickel perminvar ferrite

This study examined the impact of cobalt-doped cadmium–nickel perminvar ferrite on the electrical and dielectric properties of chromium (Cr²⁺) additions. The two-stage sintering ceramic process was used to manufacture the polycrystalline ferrite samples with compositions of Co_0.02Cd_0.2+xNi_0.58−xFe_2.2O₄ (x = 0.08) and Co_0.02Cd_0.28Ni_0.5Cr_0.2Fe₂O₄. The electric behavior of all perminvar ferrites was presented by measuring temperature-dependent resistivity and frequency-dependent resistivity. At 30 °C, the Cr-doped sample had a DC resistivity (ρ_dc) of 502.12 Ω-cm, which was much higher than the non-doped samples. This suggests that Cr²⁺ addition leads to increased resistivity. At 1 kHz, the Cr-doped sample has an AC resistivity (ρ_ac) of 4644.28 Ω-cm, indicating higher resistance due to Cr doping. The difference in DC and AC resistivity is due to the material’s different conduction methods and frequency responsiveness. The findings indicate that introducing Cr improves the material’s electrical resistivity and dielectric characteristics, making it ideal for high-frequency applications and devices with low energy loss. Variations of dielectric constant and dielectric loss with frequency and temperature had also been studied. The change in DC resistivity displayed a decreasing pattern with the increase in temperature and was found to be almost constant up to a specific temperature and then almost unchanged. To study the pattern of dielectric properties, dielectric constant (ε′), dissipation factor (tan \(\delta \) $\delta$ ), and dielectric loss (ε″) were graphed with temperature. These behaviors exhibited a decreasing pattern with the initial rise of temperature and then increased steeply until reaching a dielectric transition temperature. Frequency-dependent ac resistivity, dielectric constant, and dielectric loss of all ferrites decline with the rise in frequency, which exhibits conventional ferrimagnetic behavior. These properties showed that dispersion was because of Maxwell–Wagner kind of space charge interfacial polarization in fulfillment of Koop’s two-layer model.