Professor

Ph: +91-80-2293 3255
Fax:+91-80-2360 7316
E-mail: nravi@mrc.iisc.ernet.in

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Brief Biodata:

Dr. Ravishankar obtained his B.Tech. degree in Metallurgical Engineering from ITBHU, Varanasi in 1991. He then continued in the same field and obtained his M. Sc. and Ph. D. degrees from IISc, Bangalore in 1993 and 1998 respectively. During his Ph. D. he spent time as a exchange program student at Toyohashi University of Technology, Japan in 1996. Following his Ph. D., he was a Post Doctoral Researcher and then Research Associate with Prof. Barry Carter’s Research Group at the University of Minnesota from 1998 till 2002. Since 2002 he has been on the faculty of the Materials Research Centre.

Research:

  • Shape controlled synthesis of noble metals and nanostructures and its properties
  • Growth of Crystals from Chemical Reactions and Thermodynamics.
  • Solvothermal Coating of Noble Metals and Semiconductors on Different Substrates
  • Synthesis of Metals and Ceramics Porous structures
  • Synthesis and Characterization of Bioceramics
  • Surfaces and Interfaces in Ceramics and Metals
  • Template Approach to Synthesis Ordered Arrays of Nanostructures
  • Patterning of Soft and Hard Thin Films
  • Crystallization of metals and ceramics in earth and space to study the effect of gravity

Research in brief:

        Our research is centred around the bottom-up paradigm for the synthesis and assembly of nanostructures. The first step is the synthesis of building blocks that will be subsequently assembled in to different mesostructures. In synthesis, the primary emphasis is on obtaining a detailed mechanistic understanding of morphology evolution for anisotropic nanostructures. We synthesize structures in the form of 1-D structures (wires and rods), 2-D form (platelets or nanoprisms) and 3-D structures with intricate shapes (primarily porous structures). In addition, we also synthesize hybrid structures based on metal nanostuctures tethered to polymer beads, silica spheres or multiwalled carbon nanotubes for various applications. The second step involves assembling the nanostuctures produced on a suitable substrate or template for various applications. We have developed a new solvothermal method to integrate synthesis and assembly in a single step process. In addition, we use the template approach to directly synthesize patterned structures on a template in a single step. We also explore the top-down approach to produce nanopatterns by controlled dewetting of continuous thin films on substrates. We owe much of our success in these areas to our capabilities for examining the structures formed at various stages, at different length scales using a combination of advanced microscopy techniques. We use the visible-light microscope, scanning electron microscopes, transmission electron microscopes and the atomic force microscope to interrogate various aspects of the structures formed.

Recent publications:

  1. Kundu, P., Turner, S., Aert, S. V., Ravishankar, N. & Tendeloo, G. V. , Atomic Structure of Quantum Gold Nanowires: Quantification of the Lattice Strain, ACS Nano, 599-606 , 8 (2014)
  2. Kundu, P., Heidari, H., Bals, S., Ravishankar, N. & Tendeloo, G. V. , Formation and Thermal Stability of Gold-Silica Nanohybrids: Insight into the Mechanism and Morphology by Electron Tomography, Angew Chem. Int. Ed., 1-6 , 5 (2014)
  3. Singhania, N., Anumol, E. A., Ravishankar, N. & Madras, G. , Influence of CeO2 morphology on the catalytic activity of CeO2-Pt hybrids for CO oxidation , Dalton Trans., 15343-15354 , 42 (2013)
  4. Roy, A., Pandey, T., Ravishankar, N. & Singh, A. K. , Single crystalline ultrathin gold nanowires: Promising nanoscale interconnects , AIP Advances, 032131-032137 , 3 (2013)
  5. Nagaboopathy, M., Ravishankar, N. & Raghavan, S. , Synergistic Effect of Reactor Chemistry and Compressive Stress on Dislocation Bending during GaN Growth , Appl. Phys. Lett., 041912-041915 , 103 (2013)
  6. Leelavathi, A. et al. , Highly photoactive heterostructures of PbO quantum dots on TiO2 , RSC Advances, 20970-20977 , 3 (2013)
  7. Leelavathi, A., Madras, G. & Ravishankar, N. , Origin of enhanced photocatalytic activity and photoconduction in high aspect ratio ZnO nanorods , Phys. Chem. Chem. Phys., 10795-10802 , 15 (2013)
  8. Kundu, P., Anumol, E. A. & Ravishankar, N. , Pristine Nanomaterials: Synthesis, Stability and Applications , Phys. Chem. Chem. Phys., 5215-5224 , 5 (2013)

For a complete list, please click on this link


Select Career Publications:

  1. Mechanism of the Early Stages of 1 plate growth in a Cu-39%Zn Alloy, N. Ravishankar, H.I. Aaronson, and K. Chattopadhyay, Metall. Mater. Trans. A, 25, 2631-2637 (1994)
  2. Magnetic Hardening Mechanism in Nanocrystalline Nd2Fe14B with 0.1% Addition of Cr, Cu, Zr, K. Raviprasad, N. Ravishankar, K. Chattopadhyay, and M. Umemoto, J. Appl. Phys., 83, 916-920 (1998)
  3. Migration of Alumina Grain Boundaries Containing a Thin Glass Film, N. Ravishankar and C.B. Carter, Acta Mater., 49, 1963-1969 (2001)
  4. Electric Field Singularity Assisted Nanopatterning, N. Ravishankar, V.B. Shenoy, and C.B. Carter, Advanced Materials, 16, 76-80 (2004)
  5. Ultrafine Single Crystalline Gold Nanowire Bundles by Oriented Attachment, A. Halder and N. Ravishankar, Advanced Materials, 19(14): p1854-58 (2007)