In Situ Optical and Scanning Probe Microscopy of Nanostructure Growth and Ionic Dynamics at the Nano- and Mesoscales
| Date/Time: | Thursday, 12 Feb 2015 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
Abstract: In situ techniques are a very powerful tool for investigating the evolution of physico-chemical phenomena, as they provide high veracity real-time information on the sequence of events and material transformations. Microscopic methods, in addition, allow probing phenomena at the micro and nanoscale, where the control over the operation of electrochemical devices happens: at the grain boundaries of a battery electrode material, in the conductive filaments of a memristor, in the space-charge layer of a gas sensor, etc. Applied to studies of vanadium dioxide nanostructure growth, in situ optical microscopy revealed details of complicated thermodynamic transformations, established two novel growth mechanisms and explained the importance of the substrate-nanostructure interaction. These findings were used to rationally design methods of VO2 nanostructure templating and doping, which is an important step toward realization of the Mott-transition FET. Furthermore, two novel scanning probe microscopy techniques and examples of their use for detecting local electrochemical activity in several ionically-active materials will be discussed. The first order reversal curve current-voltage spectroscopy employs the coupling between the ionic motion and electronic conductivity to measure the former. The time-resolved Kelvin probe force microscopy method separates surface vs. bulk ionic activity on insulating surfaces in the time domain. Discussion of the benefits and future development of both techniques as well as the use of multivariate statistical methods for extracting physical meaning from the multidimensional datasets will close the presentation.
Bio: Dr. Strelcov is a Postdoctoral Research Associate at the Oak Ridge National Laboratory. He received his PhD in Applied Physics in 2011 from Southern Illinois University and MS degree in Inorganic Chemistry in 2004 from Moldova State University, Moldova. He has published 44 papers and been recognized with several awards, including Government Scholarship from Moldavian Prime Minister. His research interests include advanced scanning probe microscopy, bias-induced transformations in low dimensional solid state materials, surface electrochemistry and gas sensorics.