Day :
Keynote Forum
Anirudha V Sumant
Argonne National Laboratory, USA
Keynote: Nanoscale tribochemical reaction drive superlubricity at macroscale with 2D materials-nanoparticles ensembles
Biography:
Anirudha Sumant is a Materials Scientist working at Center for Nanoscale Materials, Argonne National leading the research on nanocarbon materials including CVD-diamond, carbon nanotube and graphene. He has more than 22 years of research experience in the synthesis, characterization and developing applications of carbon based materials. His main research interests include electronic, mechanical and tribological properties of carbon based materials, surface chemistry, micro/nano-scale tribology, and micro-nanofabrication. He is the author and co-author of more than 100 peer reviewed journal publications, two book chapters, winner of four R&D 100 awards, NASA Tech Brief Magazine Award, 2016 TechConnect National Innovation Award, has 20 patents granted, and 11 pending and given numerous invited talks. His research in diamond materials helped in the formation of several start-up companies including NCD Technologies Inc. and AKHAN Semiconductors Inc. He is a Member of MRS, STLE and AVS.
Abstract:
In our previous studies we have demonstrated that the new super lubricity mechanism at macroscale by combined uses of graphene mixed with nanodiamonds sliding against diamond-like carbon (DLC). In particular, we showed that super low friction regime (the coefficient of friction is 0.004) is observed when graphene patches wrap around the nano diamonds and form nanoscrolls with reduced contact area sliding against an incommensurate DLC surface. In the present study, we show that other two dimensional (2D) layered material such as molybdenum disulfide (MoS2) is also capable of demonstrating super lubricity through unique tribochemical reaction with carbon leading to formation of onion-like carbon (OLC) at the tribological interface. We have observed that beyond some initial run-in period, the friction comes down to some un-measurable levels and maintains in that state for a very long period of time, despite the fact that introduced 2D film of MoS2 is only a few nanometer thick. Our detailed experimental and theoretical investigations suggest that formation of OLCs is possible through tribochemical reaction with these 2D materials that could occur at the tribological contact due to high contact pressure. These OLCs behaves in a similar way described earlier in our previous studies, providing reduced contact area and incommensurability with respect to the sliding DLC surface leading to super lubricity. We will discuss the detailed mechanism and highlight the similarities and differences with the previously demonstrated super lubricity involving graphene-nanodamond ensembles. This new discovery broadens the fundamental understanding of frictional behavior of 2D materials beyond graphene and opens a wide range of possibilities for implementing them in mechanical and tribological applications involving static, sliding, and rotating contacts.
Biography:
James C Sung was responsible for diamond production technology at GE Super Abrasives, for diamond tools development at Norton. He has set the diamond grid specifications for diamond disks used worldwide for CMP of IC wafers, and helped IPO of Kink Company in Taiwan. He co-founded graphene synthetic with Huang-He worldwide, the world's largest diamond maker located in Henan China. He is now Chairman of Applied Diamond Inc., selling the most advanced CMP diamond disks-V the manufacture of next generation interconnects.
Abstract:
Graphene is the stretched diamond (111) plane graphene can be formed martensitic alloy without breaking the carbon bonds, on diamond surface by specialty heat treatment in vacuum. In this case, Graphene on Diamond (GOD) hetero-epitaxy is similar to homo-epitaxy so the signal transmission is continuous. GOD is an ideal computational device as graphene contains the most effective transmission lattice, capable of terahertz communication by Mach 100 speed of phonon (lattice vibration). On the other hand, diamond is considered to be the most stable quantum computing solid due to its highest Debye temperature. During the quantum computing, the Q-bits must be entangled without atomic vibration, and diamond’s super hard lattice is capable to maintain this stability for milliseconds, even at room temperature. Diamond contains about 1% C13 isotope atoms in the lattice. These atoms may be ion planted and heat treated to cluster as Q-bits. The superposition of spins from the extra neutron in the nuclei would be the best mechanism for Quantum computing. With about 50 Q-bits entangled in milliseconds while these Q-bits are stationary, the vast Computational possibilities can tackle even more difficult problems that for all human transistors combined. With GOD, the quantum computing can be initiated with graphene on cubical face (100) of diamond; and the Collapsed quantum waves may exit from octahedral face (111). Thus, GOD would be the dream AI chip that Outperforms even the smartest combinations of all current computers interconnected together.
Keynote Forum
Somnath Bhattacharyya
University of the Witwatersrand, South Africa
Keynote: Odd-frequency superconducting order parameter in boron-doped nano crystalline diamond films
Time : 09:45-10:30
Biography:
Somnath Bhattacharyya is a Professor in the School of Physics at the University of the Witwatersrand, Johannesburg, South Africa since 2012. After completing his doctoral degree from the Indian Institute of Science, Bangalore in 1997 he worked as a Researcher in the USA, Germany and England. In 2007 he established his new research group the nano-scale transport physics laboratory at the University of the Witwatersrand. His major interest is in the transport properties of carbon and major achievements include the demonstration of resonant tunnel devices based on amorphous carbon, gigahertz transport in carbon devices, n-type doping of nanocrystalline diamond and developing theoretical models for transport in disordered carbon. He has published four book chapters and over 70 papers in peer reviewed journals.
Abstract:
Nanocrystalline diamond films can be described as a granular superconducting system with Josephson’s tunneling between superconducting diamond grains separated by a very thin layer of disordered sp2 hybridized (i.e. graphene-like) carbon. Presently we concentrate on electrical transport properties of heavily boron–doped nanocrystalline diamond films around the superconducting transition point based on the Berezinskii-Kosterlitz-Thouless transition. The magnetoresistance (MR) of these films was found to change from negative to a positive value at a particular temperature close to this transition which is explained through the transition from weak localization to weak anti-localization effect. Through the application of a low bias current negative magnetoresistance (MR) features can be seen with periodic oscillatory features these are attributed to tunneling associated with non-s wave order parameters in a multi-junction system. Presence of an odd frequency superconducting order parameter has been claimed from pronounced zero bias conductance peak as well as spin valve-like effect in MR. Ultimately from the angle-dependent change of critical temperature as well as the MR peaks we demonstrate signature of spin triplet superconductivity in these films. The microstructure essentially forms a graphene on diamond system which has been suggested as a good candidate for topological insulator. Hence the superconducting nanodiamond heterostructures can be useful for developing topological qubits for quantum computing, some device concepts are thus discussed.