Microstructure and magnetic properties of Fe(Co, Mn)-Zr-B alloys and some oxide nanoparticles and their applications.

Fe-Zr based amorphous and nanocrystalline alloys have been extensively investigated over the last few decades from both fundamental and technological points of view.  Considerable effort has been devoted to the understanding of systems with frustration arising from competing exchange interactions and the role of random magnetic anisotropy.  These alloys show novel phenomena such as double transition behavior, invar effect, resistivity anomalies and magnetocaloric behavior in the amorphous phase.  On the other hand, these alloys in nanocrystalline state exhibit outstanding soft magnetic properties, such as ultra low coercivity (HC), high saturation magnetization (MS), and high permeability with the substitution of suitable elements.  A systematic investigation of microstructure and magnetic properties of Fe(Co,Mn)-Zr-B alloys prepared by different synthesis routes such as melt spinning and mechanical alloying processes has been carried out. Correlation between microstructure, magnetic properties and domain structure of Fe(Co,Mn)-Zr-B alloys in amorphous and nanocrystalline state would be the main focus of my talk. Effect of magnetic field annealing on the formation of two-phase microstructure in Fe(Co,Mn)-Zr-B alloys, evolution of magnetic domain structure, the resulting magnetic properties and the correlation between them would be the central theme of the discussion. I would also be discussing the role of magnetoelastic anisotropy, surface effects and interparticle interactions in shaping the magnetic properties of the interacting amorphous ultrafine powders. In the second part of my talk I will present some of the recent results on the synthesis and magnetic properties of cobalt ferrite nanoparticles. Effect of annealing on the microstructure and magnetic properties of the nanoparticles would be discussed in detail. Moreover, possible application of the functionalized cobalt ferrite nanoparticles as bioprobes for viewing human cervical cancer cells (HeLa) in transmission electron microscopy (TEM) and confocal microscopy (CLSM) would also be discussed.