Sômiya Award 2004

Year 2004 Sõmiya Award was presented at the IUMRS-ICEM-2004 Conference in San Francisco, USA

 

Pictured from left to right are Howard Katz (MRS President),
Anthony Cheetham (UCSB), C. N. R. Rao (JNCASR),
and Robert Nemanich (IUMRS President).

 

The Year 2004 IUMRS Somiya Award was awarded to an India/USA research team led by Dr. C. N. R. Rao (JNCASR, Bangalore, India) and Dr. Anthony Cheetham (University of California at Santa Barbara, California, USA). The IUMRS Somiya award talk was given jointly by the two recipients.

Rao, along with his numerous collaborators and students, has done significant work on forming nanomaterials through soft chemistry, and his talk offered just a glimpse of the vast range of research. He started by enunciating solvothermal synthesis, using capping agents, of nanocrystals of materials such as ZnO, CdO, CdS and GaN. Excellent quality single-crystal GaN nanocrystals can be obtained for example using this technique. He described his contributions to the synthesis of metal nanocrystals such as Au and indicated that very good 2-D organization of nanocrystals is possible. Nanocrystal films can be formed at liquid-liquid interfaces with good control. He described the use of dip-pen lithography using an AFM tip to form patterns using nanoparticles including Au and Fe2O3. Next, Rao described his research relating to nanotubes including the use of organometallic precursors, one-step synthesis of carbon nanotubes, and synthesis of junction nanotubes in a reproducible fashion. He discussed the formation of nanotubes from gels using soft chemistry including Fe7S8 nanowires. He concluded with descriptions of the formation of Se and Te nanorods and nanowires.

Cheetham followed with a discussion of work by his group on direct observations of the structure of Au nanoparticles using powder neutron diffraction. Nanoparticles give very poor diffraction patterns with x-rays or neutrons. Therefore, total scattering neutron diffraction was performed using monodispersed Au nanoparticles which were carefully synthesized forming capped Au nanoparticles so as to reduce incoherent neutron scattering. Fourier transforms of the neutron data yielded pair distributed functions (pdfs) which reveal vectors between all atoms in a particle. For a nanoparticle, the maximum length of the vector is determined by its size. The pdf data can be fitted by modeling nanoparticle structure and refined. This yields lattice parameters and temperature factors and other data. Cheetham indicated that this method can be extended to other systems including the study of core-shell structures, nanowires, carbon nanotubes etc., and it is also possible to perform the experiment with short wavelength synchrotron X-rays.

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