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Material Innovations via non-equilibrium laser/ion irradiation approaches

July 1, 2019 @ 2:00 pm - 3:00 pm

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Speaker: Professor Ritesh Sacahan

Assistant Professor, Mechanical and Aerospace Engineering, Oklahoma State University

One of the most effective ways to achieve novel functionalities in nanomaterials is by adopting
fabrication methods far-from-equilibrium conditions. Such approaches are based on ultrafast structural
reordering at nano/atomic scale, giving rise to novel functionalities in the nanomaterials. This
presentation forges the correlations between the atomic/electronic structure and the properties of the non-
equilibrium nanomaterials formed by high-energy laser and ion irradiation approaches. First, we present
the fabrication of atomically disordered nanochannels in complex oxides using energetic ion irradiation,
that act as selective pathways for fast oxygen conduction in the solid-oxide fuel cells. We show the
controlled sculpting of functional nanochannels by guided electron-irradiation induced phase transitions.
Second, we reveal the emergence of unusual phenomena such as high oxidation resistance and
Ferroplasmon in bimetallic AgCo nanoparticles formed by pulsed laser-irradiation induced dewetting of
metallic films. We attribute the oxidation resistance in AgCo nanoparticles to cathodic protection of Ag
arising from galvanic coupling with Co. The appearance of Ferroplasmons, the intense surface plasmons,
takes place on the ferromagnetic Co which is conventionally a poor plasmonic material. These excites in
the visible spectrum with comparable intensity to those in plasmonic Ag surface. Last, we discuss the
discovery of a new metastable phase of carbon, Q-carbon, was recently discovered by our collaborative
team via laser-induced ultrafast melting and quenching of amorphous carbon. By incorporating extremely
high B-doping (~27 at%) concentration, Q-carbon exhibits superconducting nature below T c at 55 K,
which is the highest among BCS superconductors (40 K in MgB 2 ). We attribute this to the emergence of
shallow energy-state appearing near Fermi-level. With these discoveries, I present the non-equilibrium
nanofabrication as the pathway to address the toughest challenges in condensed matter physics.

Dr. Ritesh Sachan is an assistant professor, Department of Mechanical and Aerospace Engineering at
Oklahoma State University. His research interests primarily lie in developing a quantitative understanding
of the structure-property correlations in highly non-equilibrium nanostructures and thin films using the
approach of laser/ion irradiation-induced nanofabrication and advanced electron microscopy. Previously,
Dr. Sachan worked at Army Research Office as an NRC Research Associate (2016-2018) and Oak Ridge
National Laboratory as a Postdoctoral Researcher (2013-2016). His research efforts have resulted in ~70
journal papers, 800+ citations, 1 book chapter and numerous invited/contributed talks to date. He has
received the prestigious NRC fellowship by National Academy of Sciences in 2016 and was also named
for Young Leader Professional Development Award in 2015 by The Minerals, Metals and Materials
Society (TMS).


July 1, 2019
2:00 pm - 3:00 pm
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EB1 – 3003
NC United States


MSE Department


Ritesh Sachan