Synthesis, magnetic and dielectric properties of Er–Ni doped Sr-hexaferrite nanomaterials for applications in High density recording media and microwave devices

A sol–gel combustion method has been successfully employed for the synthesis of Sr-hexaferrite nanomaterials doped with Er3+ and Ni2+ at strontium and iron sites, respectively. The X-ray diffraction analysis confirmed the single magnetoplumbite phase and the crystallite size was found to be in the range of 14–16nm, suitable for obtaining signal-to-noise ratio in the high density recording media. The magnetic properties such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) were calculated from hysteresis loops. Ms, Mr and Hc are observed to increase with the Er–Ni content. The dielectric constant (ε´) and dielectric loss (tanδ) is found to decrease with the increase in frequency and is explained on the basis of Maxwell–Wagner and Koops theory. The decrease in dielectric constant and dielectric loss but increase in saturation magnetization and remanence with Er–Ni content suggests that the materials are suitable for applications in microwave devices and high density recording media . ► A Simple and economic method has been used for synthesis of materials. ► The main aim for substitution of Er–Ni in Sr-hexaferrite is to improve magnetic properties and to reduce the crystallite size. ► We are able to improve the saturation magnetization and remanence with the doping of Er–Ni. ► Crystallite size is in the range 16–14nm, which is much smaller than that reported earlier. ► Dielectric constant is reduced which makes the material suitable for microwave devices.