High frequency dielectric response and magnetic studies of Zn1−xTbxFe2O4 nanocrystalline ferrites synthesized via micro-emulsion technique

Abstract Tb 3+ -doped nanocrystalline zinc ferrites with a nominal composition of Zn 1− x Tb x Fe 2 O 4 ( x =0, 0.03, 0.06, 0.09, 0.12 and 0.15) were prepared by micro-emulsion method and were annealed at 600 °C for 8.5 h. The synthesized samples were characterized by thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and dielectric measurement techniques. The powder XRD patterns confirm the single phase cubic spinel structure, indicated that doping nanoferrites with small concentrations of terbium ions allowed their entrance to the spinel lattice and the crystallite size is found in the range of 16–24 nm. The dielectric constant ( e ) and dielectric loss (tan δ ) of all the samples were measured in the frequency range 100 MHz–3 GHz at room temperature. The dielectric constant and dielectric loss of the samples are found to decrease with increase in frequency and Tb 3+ content. The reduction in the dielectric parameters is attributed to the obstruction incorporated in electron exchange mechanism caused by the lockup among iron and terbium cations. The magnetic properties revealed that these terbium doped nanocrystalline zinc ferrites exhibit ferrimagnetic behavior. The high saturation magnetization and coercivity along with smaller dielectric parameters having Tb-contents suggests that the materials are suitable for applications in memory devices and high frequency applications.