Effect of Gd~(3+)-Cr~(3+) ion substitution on the structural, electrical and magnetic properties of Ni-Zn ferrite nanoparticles

摘要

Gd~(3+) doped nickel zinc nanoceramics with general formula Ni_(0.4)Zn_(0.6)Cr_(0.5)Gd_xFe_(1.5-x) O4 (where x=0.00, 0.02, 0.04, 0.06) were synthesized by solution combustion method using oxylyldehydrazine as a fuel. The obtained powder was sintered at 1000°C for 2h. The detailed structural , electrical and magnetic studies were carried out through X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), impedance spectroscopy and vibrating sample magnetometer (VSM). The XRD pattern of as prepared sample confirms the formation of single phase with cubic spinel structure . The average crystallite size was found to be 34 to 19 nm and decreases with increasing Gd~(3+) ion concentration . The IR spectra exhibited two expected absorption bands between 600 to 300 cm-1 corresponding to the stretching vibrations of tetrahedral (A) and octahedral (B) metal oxygen vibrations. The variation of room temperature real (ε) and imaginary (ε) part of dielectric permittivity as a function of frequency and composition have been studied in the frequency range from 40Hz to 10MHz . The real and imaginary dielectric permittivity decreases with increase in frequency as well as Gd~(3+) concentration, which is normal behaviour of ferrite material and results have been explained on the basis of Maxwell-Wagner's two layer model. The VSM results showed that the Gd~(3+) concentration had significant impact on the saturation magnetization and coercivity , x=0.02 shows the highest value of dielectric constant and saturation magnetization, thus the material is becoming low loss dielectric and highly resistive and soft magnetic material due to Gd-Cr doping.