Synthesis and Characterization of Lanthanum Strontium Cobalt Ferrite Nanoparticles Prepared by Thermal Decomposition of the Mixed Metal Acetylacetonates

摘要

Aims: To synthesis lanthanum strontium cobalt ferrite, La0.8Sr0.2CoyFe1-yO3-δ (y=0, 0.2, 0.4) nanopowders via metal-organic precursors (acetylacetonates), determine the composition, structure and magnetic properties. Place and Duration of Study: Laboratory of Noxious Chemistry and Environmental Engineering – University of Dschang and Magnetic Materials Unit, National Chemical Laboratory, Pune – India between November 2013 and March 2015. Methodology: Mixed lanthanum strontium cobalt iron acetylacetonate precursors were synthesized at 55°C by co-precipitation and heated at 450°C to undergo thermal decomposition in order to form mixed lanthanum strontium cobalt ferrite alongside secondary phases. They were further calcined at 1000°C to form single perovskite phase. The structure, morphology and elemental analyses were determined by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy respectively. The magnetic properties were determined at room temperature using a vibrating sample magnetometer. Results: X-ray diffraction studies of heat-treated La0.8Sr0.2CoyFe1-yO3-δ showed that single phase nano-sized perovskite powders were formed with structures varying from orthorhombic (y = 0, 0.2) to rhombohedral (y =0.4) as the Co content increased. Microstructure analysis indicated polycrystalline spherical nanoparticles with agglomeration tendencies. Elemental analysis by X-ray energy dispersive spectroscopy indicated that the desired metals in their stoichiometric proportions were obtained. From the measured hysteresis loops of La0.8Sr0.2CoyFe1-yO3 at room temperature using a vibrating sample magnetometer, all the compositions exhibited anti ferromagnetism and a weak ferromagnetic component along the c-axis as a result of the complex interaction of different valences of the transition metal ions. Increasing coercive fields were observed with increasing Co content while spontaneous magnetization and saturation magnetization decreased with increased in Co substitution. Conclusion: La0.8Sr0.2CoyFe1-yO3 was successfully prepared by the thermal decomposition method. Their structural and magnetic properties were found to vary with the Co content. These results show that the synthesized materials possess potential magnetic applications in data storage, logic, magnetic bubble memory, magnetic sensors.