Structural and magnetic properties of Co-Al substituted Ni ferrites synthesized by co-precipitation method

Abstract

Controlled growth and careful characterizations of nanocrystalline Ni ferrites are demanding for high density recording media. Ferrites of the form Ni((1-x))CoxFe2-x AlxO4 (where x = 0.0, 0.2, 0.4, 0.6 and 0.8) are prepared by the co-precipitation method. The process is investigated with simultaneous thermogravimetric-differential thermal analysis (TG-DTA). The FESEM images display the nanostructural features of the samples with Gaussian distribution and the XRD analysis confirm the formation of single spinet phase with mean particle size 15-19 nm. Our results suggest that these crystallites are small enough to obtain the suitable signal-to-noise ratio appropriate in the high density recording media. The wide variation of saturation magnetization (M-s), remanence (M-r) and coercivity (H-c) evidenced in the range of 31.02-45.56 emu/g, 12.74-19.80 emu/g and 56-563 Oe, respectively are promising for diversified applications. The conduction mechanism is understood using complex impedance measurements. Our simple and economic preparation method may constitute a basis for the production of large scale high quality Ni ferrite nanopowders useful for memory devices.