Investigations on dielectric and impedance properties of M-type hexaferrite

Abstract

The M-type strontium hexaferrite SrFe12O19 nano particles with nominal composition were prepared by self-propagating high temperature synthesis route. The ac conductivity and dielectric properties of SrFe12O19 samples were studied by using complex impedance technique. The dielectric properties like dielectric constant ( $$ \upvarepsilon^{\prime } $$ ), dielectric loss (tan δ) and ac conductivity (σac) were measured at different calcination temperatures in the frequency ranges from 50 Hz to 5 MHz. The frequency dependence of ac conductivity is analysed by the power law σ(ω)ac = Bωn which is typical for charge transport by tunnelling processes. The temperature dependence of frequency exponent n was investigated to understand the conduction mechanism at different calcination temperatures. The conduction mechanisms are mainly based on polaron hopping conduction. The results of the cole–cole diagram of $$ {\text{Z}}^{\prime } $$ and $$ - {\text{Z}}^{{\prime \prime }} $$ at different temperatures ensure the presence of grain and grain boundaries having different conductivities in the investigated nano particle samples. The dielectric and impedance properties of the prepared strontium hexaferrite samples were discussed in view of applications for microwave devices, permanent magnets and high frequency magnetic recording media.