Physics Colloquium - Graduate Oral Presentations

Thursday, February 28 @ 4pm – 139 Fisher Hall

Qing Guo (Advisor: Prof. Ravi Pandey) will present “Thermodynamic and Mechanical Stability of Crystalline Phases of Li2S2. In lithium-sulfur battery, Li2S2 is one of the key intermediate products which may exist as insoluble solid in a battery system. In this article, the low-energy crystalline phases of Li2S2 are investigated using density functional theory coupled with the Van der Waals correction terms. The calculated results find that the tetragonal, triclinic and hexagonal phases of Li2S2 phases are thermodynamically stable with the preference for the hexagonal phase to be the ground state. The low-energy Li2S2 phases also exhibit highly anisotropic elastic properties which can be attributed to the unique S-S bond orientations in their lattices. We believe that the elastic modulus in Li-S solids can be properly tuned if the S-S bonds orientation and distribution can be controlled during the synthesis process, which may be helpful for the development of functionalized cathode in the Li-S battery.


Tyler Capek (Advisor: Prof. Claudio Mazzoleni) will present “Probing Single Scatter Albedo of Aerosol at
High Relative Humidity”. Aerosol influence Earth’s radiative budget by scattering and absorbing solar radiation and through aerosol-cloud interactions. Measuring aerosol’s optical properties and accounting for them in atmospheric models is an open challenge. The presence of water vapor is one of the most important environmental influences as it can have significant effects on aerosol’s optical properties. A humidified Cavity Attenuated Phase Shift Albedometer was used to investigate the optical properties of aerosol. Light scattered by ammonium sulfate was enhanced by as much as 3.5 times when exposed to a relative humidity of 85%. Likewise, absorption by nigrosin was enhanced by as much as 1.2 times. Preliminary experiments involving soot showed no signs of water uptake, however we plan to conduct more experiments with soot in the future.

Thursday, February 28, 2019 at 4:00 p.m. to 5:00 p.m.

Fisher Hall, 139
1400 Townsend Drive, Houghton, MI 49931

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Department of Physics


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