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Updated on: March 16, 2014  
     
  FACULTY - Karuna Kar Nanda, Professor (Research Areas)  
 
 
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Last Updated: March 16, 2014
Default faculty mailing address: Materials Research Centre, Indian Institute of Science(IISc), Bangalore - 560012, INDIA.
Phone: Country code-91; Bangalore city code 80 from abroad and 080 from India.

 

Karuna Kar Nanda
Professor

Ph:
Off: +91-80-2293 2996
Res: +91-80-2360 7696
Fax:+91-80-2360 7316
E-mail: nanda@mrc.iisc.ernet.in

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Research:
  • Synthesis of nanoparticles, nanowires and carbon nanotubes
  • Electrical, optical and thermodynamic properties of different nanostructures
  • Field emission and gas sensing behavior of different nanostructures

Research Areas:
Materials in the micrometer scale mostly exhibit physical properties the same as that of bulk form; however, materials in the nanometer scale may exhibit physical properties distinctively different from that of bulk. There are two major effects that are responsible for the change in nanoparticle properties due to the size variations. First, the intrinsic properties of the nanoparticles are transformed by quantum confinement. Below a critical size, there is substantial variation of fundamental optical and electrical properties with size, which can be realized when the energy level spacing exceeds the thermal energy. Second, the number of surface atoms in a nanoparticle is a large fraction of the total number of atoms and as a result, melting temperature suppression, solid-solid phase transition, etc. have been observed.

Synthesis: Efforts are being made to synthesize nanoparticles, nanowires and carbon nanotubes by simple methods. Metal oxide nanowires with very large aspect ratio have already been achieved simply by heating the metal in air atmosphere. We have also successfully synthesized millimeter long carbon nanotubes by a pyrolysis technique.

Properties: The properties of a material decide its application. As the size of a material is reduced, the band gap increases, metallic systems behave like semiconductors, the particles melts at low temperature. Therefore, it is essential to investigate different properties of nanostructures to ascertain their applications at different conditions. Electrical, optical and thermodynamic properties of different nanostructures are being investigated.

Field emission: Field emission (FE) is a unique quantum-mechanical effect where electrons tunnel from condensed matter into a vacuum. FE is of great commercial interest in flat panel displays, x-ray sources, and other vacuum microelectronic devices. In past decades, research in this area mainly focused on carbon-based materials because of their high mechanical stability, good conductivity and negative electron affinity. One-dimensional (1D) nanostructured materials such as carbon nanotubes (CNTs)-were particularly thought to be good candidates for FE as they have the added advantages of high aspect ratio, which enhances the electric field on the sharp end of their structures. Many researchers consider ZnO 1D nanostructures as good field emitters and has been investigated intensively as a potential alternative for producing field emission with low threshold and high efficiency. Generally, ZnO 1D nanostructures have shown better field emission characteristics for needle-like structures because sharper tips increase the effective electric field at the tips. The other advantages of ZnO are that it is thermally stable and intrinsically oxidation resistant. Research on ZnO 1D nanostructures as field emitters has only recently begun, so their field emission characteristics have not been optimized sufficiently. Various 1D ZnO nanostructures-such as nanowires, nanoribbons, tetrapods-have been fabricated to investigate the FE behavior and is under progress.

Gas sensing: The use of sensors to monitor gas atmospheres represents a growing market resulting from strategies for intelligent process management, environmental protection and medicinal diagnostics as well as from the domestic, aerospace and automobile sector. Hence, the development of fast responding, sensitive and especially highly selective gas sensor materials is of major interest. SnO2 is an n-type semiconductor material and is one of the most investigated materials. The investigation on the gas sensing behavior of ZnO and CNTs is under progress.

 

 

 

 

 
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