Effect of annealing on phase composition, structural and magnetic properties of Sm-Co based nanomagnetic material synthesized by sol-gel process

• Published in: Journal of magnetism and magnetic materials 2012-07, Vol.324 (13), p.2158-2162
• Main Authors: Suresh, G., Saravanan, P., Rajan Babu, D.
• Format: Article
• Language: English
• Subjects: Annealing; Chemical synthesis; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Ferromagnetism; Magnetic nanoparticle; Magnetic properties; Magnetic properties and materials; Magnetic properties of nanostructures; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Nanocomposites; Nanomaterials; Nanostructure; Phase composition; Physics; Samarium cobalt; Sol gel process
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2012.02.038

Sm-Co based nanomagnetic material was synthesized by means of a Pechini-type sol-gel process. In this method, a suitable gel-precursor was prepared using respective metal salts and complexing agent such as citric acid. The gel-precursor was dried at 300°C and then subjected to various reductive annealing temperatures: 350, 500 and 600°C. The nanopowders so obtained were characterized for their structure, phase composition and magnetic properties. FT-IR studies on the gel-precursor showed the binding of metal cations with the citrate molecules in the form of metal-citrate complex. The gel-precursor, which was annealed at 350°C showed the presence of both meta-stable cobalt carbide (Co2C, Co3C) and Co3O4 phases; while the sample annealed at 500°C indicated the sign of SmCo5 phase. Upon increasing the reductive annealing temperature to 600°C, crystalline phase such as fcc-Co and Sm2C3 were formed prominently. FE-SEM analysis revealed the change in sample morphology from spherical to oblate spheres upon increasing the annealing temperature. VSM measurements demonstrated ferromagnetic nature at room temperature for all the nanopowders obtained irrespective of their after reductive annealing temperature. ► Pechini type sol-gel technique was used to synthesize Sm-Co based nanoparticles. ► Formation of metal citrate complex has been confirmed using FT-IR spectroscopy. ► Annealing at different temperature in H2 atmosphere shows the evolution of variety of crystallographic phases. ► All the synthesized samples show ferromagnetic property at room temperature.