Keywords
Abstract
A systematic investigation on the phase formation, magnetic, dielectric and impedance properties of strontium hexaferrites doped with Nd and Nd-Mg was performed. All ferrite samples were prepared by the citrate-precursor method and characterized with a combination of X-ray diffraction, Vibrating sample magnetometer and impedance analyser. XRD analysis confirms the magnetoplumbite structure with space group p63/mmc without any secondary phase. The lattice parameter ratio c/a lies in the range of 3.92 to 3.94 and shows that the prepared material exhibits M-type hexagonal structure. An increase in coercivity and a decrease in magnetization were observed for all the samples. Large value of coercivity suggests that these materials are useful in longitudinal recording media. Further, it was found that the value of magnetocrystalline anisotropy constant K1 decreases with the substitution of Nd and Nd-Mg. Measurement of dielectric loss and dielectric constant were performed as a function of temperature and frequency. Dielectric constant and ac conductivity of Sr0.95Nd0.05Mg0.05Fe11.95O19 is more as compared to Sr0.95Nd0.05Fe12O19 and SrFe12O19 for all frequencies. The value of grain boundary resistance (Rgb) of Sr0.95Nd0.05Fe12O19 is less as compared to SrFe12O19 and Sr0.95Nd0.05Mg0.05Fe11.95O19 and vice versa trend is observed in the value of capacitance of the grain boundary (Cgb) and in the values of relaxation time (τgb).