Magnetic, elastic, dielectric, microwave absorption and optical characterization of cobalt-substituted nickel spinel ferrites

摘要

Magnetic, elastic, dielectric, microwave absorption and optical properties of nickel cobalt ferrites Ni_(1-x)Co_xFe_2O_4(x = 0.0, 0.15, 0.30, 0.45, 0.60, 0.75, 0.90, 1.0) synthesized using Pechini's sol-gel method are investigated. Saturation magnetization, coercivity and Curie temperature increased with doping of cobalt. An optimized combination of high M_S (86.12 emu g~(-1)) and lower coercivity (694.7 Oe) was obtained for composition NC 0.90. Curie temperature increased from 602 ℃ to 705 ℃ as amount of Co increased from 0.0 to 1.0. In FT-IR spectrum, characteristic absorption bands were observed in 400-600 cm~(-1) range. Impedance analyzer was used to determine dielectric and impedance properties in 20 Hz-120 MHz frequency range. The prepared ferrites were evaluated for their applications in 12.4-18 GHz frequency band using vector network analyzer (VNA). Minimum reflection loss of —44.48 dB at 15.74 GHz frequency was obtained for composition NC 0.90. Optical spectra at excitation wavelength of 350 nm show sharp peaks around 330 nm in all the compositions.