Conferences - Seminars

  Monday 30 April 2018 13:15 - 14:15 MXF 1

High-Pressure Synthesis: from Semiconductor Optical Fibers to Carbon Nanothreads

By Prof. John V. Badding, Penn State University USA

Pressure is a thermodynamic variable that is as fundamental as temperature but is arguably underutilized in materials chemistry research. It can, for example, control interatomic distance, tune chemical reaction kinetics and thermodynamics, allow for solvents with hybrid liquid-like and gas-like properties, and infiltrate molecules and materials into near atomic scale voids. Our group has used pressure to synthesize semiconductor optical fibers that integrate electronic and photonic functions.1  The fibers themselves are treated as miniature chemical reactors, enabling practical high-pressure deposition that would otherwise be difficult or impossible.   Using this approach, we have demonstrated single crystal, small core silicon and germanium fibers with useful nonlinear properties, in-fiber GHz bandwidth photodiodes, and tunable chromium-doped zinc selenide fiber lasers. We have extended the deposition approaches developed for fibers to semiconductor and metal “metalattice” nanomaterials that offer the possibility of tuning properties by quantum confinement while allowing for long-range transport of electrons and phonons in all three dimensions.2  Finally, we have synthesized carbon and carbon nitride nanothreads under pressure from benzene and pyridine molecules, respectively.  These  one-dimensional and sp3-bonded “flexible diamond” nanostructures are the last remaining entry in the matrix of carbon nanomaterial dimensionality (0D/1D/2D/3D) and bonding hybridization (trigonal sp2/tetrahedral  sp3).3  The examples set by carbon and carbon nitride nanothreads suggest that practical pressure synthesis from small molecules of a large family of extended carbon materials with a diversity of useful, tunable properties may be possible.

(1) Sparks, J. R.; Sazio, P. J. A.; Gopalan, V.; Badding, J. V. Annu. Rev. Mater. Res. 2013, 43, 527-557.

(2) Liu, Y. Z.; Kempinger, S.; He, R. R.; Day, T. D.; Moradifar, P.; Yu, S. Y.; Russell, J. L.; Torres, V. M.; Xu, P. T.; Mallouk, T. E.; Mohney, S. E.; Alem, N.; Samarth, N.; Badding, J. V. Nano Lett. 2018, 18, 546-552.

(3) Fitzgibbons, T. C.; Guthrie, M.; Xu, E. S.; Crespi, V. H.; Davidowski, S. K.; Cody, G. D.; Alem, N.; Badding, J. V. Nat. Mater. 2015, 14, 43–47.

Bio: John V. Badding is Professor of Chemistry, Physics, and Materials Science and Engineering at Pennsylvania State University, USA.  After receiving a Ph. D in the Department of Chemistry at U.C. Berkeley in 1989, he did post-doctoral work with R.J. Hemley and H.K. Mao at the Carnegie Institution of Washington and then moved to Penn State.  He is the recipient of a David and Lucile Packard Foundation Fellowship, an NSF National Young Investigator Award, and the 2015 Faculty Scholar Medal at Penn State.  He is the author of over 200 publications in the general area of materials science and chemistry.

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