Structural and magnetic properties of aluminium-copper substituted cobalt ferrite nanoparticles sintered at various temperatures

Abstract

Nanoferrites, especially spinel ferrites have evoked greater attention in the recent years because of their many potential technological applications. Properties of nanoferrites could be tailored and improved by the incorporation of suitable divalent, trivalent or tetravalent ion impurities into the spinel lattice. Hence the investigation on the properties of substituted nanoferrites helps to improve the performance of these materials and make their applications more diverse. Study of fundamental properties of materials is crucial, as it may lead to the development of new area of potential application. Nanocrystalline copper-cobalt spinel ferrites and nanocrystalline aluminum substituted copper cobalt spinel ferrites with general formula of Co1-xCuxFe2-xAlxO4, (0.0= x = 0.8) were synthesized using co-precipitation method and sintered from 600 °C to 900 °C. The synthesized nanoferrite samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). XRD analysis confirmed a single phase spinel structure with the crystalline size between 14-26 nm which is calculated using Scherrer’s formula. This size is the most suitable for high density recording media application. The infrared spectra reveal two prominent frequency bands in the wavenumber range of 350-600 cm-1, which confirm the cubic spinel structure and completion of chemical reaction. Substitution of aluminum and copper to cobalt ferrites has made significant changes in the magnetic properties of nanoferrites. Saturation magnetization was observed to decrease by copper and aluminum substitution from 61.6-17.6 emu g-1 at 600 °C to 49.5-25.8 emu g-1 at 900 °C. The increasing trend of magnetic coercivity from 846.9-1117.2 Oe at 600 °C to 219.4-244.0 Oe at 900 °C was consistent with crystallinity of the samples. The simple, economic and environmental friendly sample preparation method using co-precipitation method has contributed towards the controlled growth of high quality ferrite nanopowder and the suitable values of magnetization that can be applied to high-density recording media and microwave devices.