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Department of Chemistry Seminar

November 2, 2020 @ 4:10 pm - 5:00 pm

Chemistry Department Seminar

 Monday, November 2nd @ 4:10 pm – 5:00 pm |  ZOOM Only

 Dr. Sakun Duwal ,  Senior Staff Scientist at Sandia National Laboratories

Chemistry Department Host: Choong-Shik Yoo

 Title: Materials investigation at high pressure using dynamic compression

 Abstract:

Studying materials at extreme conditions is not only relevant to nuclear weapon conditions, but also to planetary interiors. Highly accurate equation of state data at extreme conditions provides a solid basis for models that enable predictive simulation of material properties. In this talk, I will cover the investigation of two different material categories at extreme conditions: pre-compressed H2-He gas-mixtures and solid TiO2 single crystals. Studying pre-compressed samples of H2-He mixtures under dynamic loading allows us to access unique P-T states off of the principal Hugoniot. The understanding of material behavior at these P-T states is crucial to comprehend the origin and evolution of gas planets. Furthermore, the validation of mixture models has been a long-standing topic of interest with numerous conflicting theoretical results, particularly for non-ideal hydrogen systems. In this talk, I’ll present the experimental results on the pre-compressed samples of H2-He mixtures using pulsed-power-driven flyer plates at the Z-facility, and impact studies on the two-stage light gas gun.

The high-pressure response of titanium dioxide (TiO2) is of interest because of its numerous industrial applications and its structural similarities to silica (SiO2). My team and I used three platforms—Sandia’s Z machine, Omega Laser Facility, and density-functional theory-based quantum molecular dynamics (QMD) simulations—to study the equation of state (EOS) of TiO2 at extreme conditions. We used magnetically accelerated flyer plates at Sandia to measure the Hugoniot of TiO2 up to pressures of 855 GPa. We used a laser-driven shock wave at Omega to measure the shock temperature in TiO2. Our Z data show that rutile TiO2 reaches 2.2-fold compression at a pressure of 855 GPa, and the Omega data show that TiO2 is a reflecting liquid above 230 GPa.

 

Bio:

Sakun Duwal received her Ph.D. in Physical Chemistry in May 2018 from Washington State University, under the supervision of Prof. Choong-Shik Yoo. While at WSU, she studied chemistries of sulfides, azides and oxides, and gained expertise in high-pressure spectroscopy and diffraction using light sources at APS in Argonne National Laboratory and SPring-8 in Japan. In August of 2018, she took a position as a Postdoctoral Appointee at Sandia National Laboratories in Albuquerque, NM, under the supervision of Chris Seagle, Marcus Knudson and Seth Root. In 2019, she was converted to her current position as a Staff Scientist. Sakun has been leading the pre-compression studies of gas-mixtures at Sandia’s Z-machine and hyper velocity gas-guns. Sandia’s Z-machine is the world’s largest and most powerful pulsed power machine, which allows its users to realize extreme states comparable to the deep interiors of Jupiter, Saturn and Neptune. At Sandia, Sakun has expanded her abilities to include proficiency in laser shock experiments at the OMEGA facility at the University of Rochester and dynamic x-ray scattering at the Dynamic Compression Sector (DCS) at Argonne National Laboratories.

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Details

Date:
November 2, 2020
Time:
4:10 pm - 5:00 pm
Event Categories:
,

Organizer

Dr. Choong-Shik Yoo
Phone:
509-335-2712
Email:
csyoo@wsu.edu
Website:
http://yoo.chem.wsu.edu/home