Development of CO2 laser-heating for the study of wide band gap oxide materials
Christian Childs
Ph.D. Candidate, Department of Physics and Astronomy
The ability to access a vast region of the pressure-temperature landscape using energy density tuning enables exotic states of matter to be probed. A well documented method for such exploration, under static conditions, is the use of the laser-heated diamond anvil cell (LH-DAC), utilizing a combination of high pressure (> 300 GPa) and high temperature (> 5000 K). Combining the LH-DAC with in situ synchrotron techniques utilizes characterization methods to measure structural and electronic responses at these extreme conditions.
The wavelength of the laser source defines the type of interaction with the sample that occurs, with metals typically being heated using near-IR light through an inverse-Bremsstrahlung process, while insulators are transparent at these wavelengths and must be coupled with mid-IR light through anharmonic polariton-phonon scattering processes. This technique of directly heating insulators is under developed and poorly understood.
I will present our development of CO2 laser heating techniques to directly heat a series of wide band gap insulators, La2Sn2O7, ZrO2, and CeO2, under high pressure conditions. As the emissivity of insulators are poorly constrained under extreme conditions, limiting optical pyrometry techniques, I will present a series of new, powerful tools for determining the absolute temperature of such systems. In addition to demonstrating the design of instrumentation here at UNLV I will present two dedicated laser heatings systems at Argonne National Laboratory's Advanced Photon Source at sector 16-IDB for in-situ x-ray diffraction and at sector 16-BMD for in-situ x-ray absorption spectroscopy. Both of these instruments are the first of their kind, permitting the direct probing of warm dense matter and providing the scientific community with the tools of tomorrow.
Committee Members:
Dr. Ashkan Salamat, Advisory Committee Chair
Dr. David Shelton, Advisory Committee Member
Dr. Andrew Cornelius, Advisory Committee Member
Dr. Paul Forster, Graduate College Representative
The defense presentation is open to the public via Webex conference meeting hosted by Dr. Ashkan Salamat
Friday, Apr 17, 2020 11:00 am | 1 hour | (UTC-07:00) Pacific Time (US & Canada)
Meeting number: 285 005 097
Password: SJiXY3633ms
https://unlv.webex.com/unlv/j.php?MTID=me0be388aa0febe032efd7fb8e5b721d9
Join by video system
Dial 285005097@unlv.webex.com
You can also dial 173.243.2.68 and enter your meeting number.
Join by phone
+1-415-655-0001 US Toll
+1-415-655-0001 US Toll
Access code: 285 005 097
