Kalyan Mandal
S N Bose National Centre for Basic Sciences, India
Title: Transition metal oxide nanostructures and their novel properties
Biography
Biography: Kalyan Mandal
Abstract
Iron and other transition metal oxides nanostructures receive considerable attention due to their extensive technological applications in high density magnetic storage media, high frequency devices, magnetically assisted drug delivery, cell isolation, MRI contrast agents, immobilization of proteins and enzymes, biosensors and so on. We observed many novel and enhanced properties in those oxides depending on their shapes and sizes. They can be functionalized with suitable ligands to get biocompatible and water-soluble nanostructures with interesting multifunctional properties. For example, intrinsic multicolor fluorescence in MnFe2O4 nanoparticles (NPs)/hollow spheres (NHSs) from blue, cyan, and green to red is observed upon functionalization with a small organic ligand such as Na-tartrate because of ligand-to-metal charge transfer from tartrate ligand to lowest unoccupied energy level of Mn2+/3+or Fe3+ of the NPs and Jahn-Teller distorted d-d transitions centered over Mn3+ ions in the Nanostructures. CoFe2O4 nanoparticles functionalized with surfactants having π-acceptor/π-donor head group along with different chain-length show much higher coercivity compared to bare particles due to NP-ligand interaction which modifies the splitting of d-orbital energy levels as well as spin motion of surface Co+2 ions. Many of the above oxide nanostructures show excellent photocatalytic activities and potential for various biomedical applications depending on their shape, size and surface functionalizations.