Effect of Al³⁺doping on dielectric properties of cobalt ferrite nanoparticle for using in high frequency applications

Aluminum doped cobalt ferrite nanoparticles(CoFe_2–xAl_xO₄(x = 0.0 and 0.5)) were synthesized by wet chemical co-precipitation method. X-ray diffraction pattern confirmed the successful doping of the smaller cation of Al³⁺ and the single-phase cubic spinel structure of the prepared nanoparticles. The crystallite size of nanoparticles was examined ~25 nmusing X-ray diffraction data.The lattice parameter ‘a ’ also decreased by doping the Al³⁺cation. Two functional groups and fundamental peaks of calcined samples were identified byFourier-transform infrared spectroscopy in the range of 450–600 cm⁻¹, these characteristic absorption bandsconfirmed the cubic spinel structure of prepared nanoparticles. Field emission electron microscopy images confirm the formation of nearly spherical ferrite nanoparticles with an average size ~25–30 nm that is in good agreement with XRD results. Magnetic hysteresis study at room temperature confirmed the ferrimagnetic nature of the prepared samples and the decrease in saturation magnetization (M_S = 74–44 emu/g) and reduction in coercivity (H_C = 627.8–539.4 Oe) due to doping the Al³⁺cation. Improved values of dielectric constant, low dielectric loss and resistivity were displayed by Al³⁺cation doped ferrite nanoparticles and has been measured at room temperature for frequency dependence in the range of 100 Hz–10 MHz using impedance analyzer. It is revealed strong dependence of dielectric parameters on frequency and Al³⁺ ion content. Doping the Al³⁺ cation was increasing the values of dielectric constant and dielectric loss for (CoFe_2–xAl_xO₄(x = 0.0 and 0.5)) while decreases the electrical resistance of prepared nanoparticle. results explored the capability of the Al doped cobalt ferrite to be suitable for high frequency applications and magnetic memory devices. Graphical Abstract: [Figure not available: see fulltext.].