This is a past event.
Thursday, March 4 @ 4pm – Zoom
Elise Rosky [Co-Advisors: Will Cantrell, Raymond Shaw] will present:
Simulations of Homogeneous Ice Nucleation Under Negative Pressures
Despite its ubiquity, the physics governing the phase transition from liquid water to ice is still under investigation. The interactions between water molecules are surprisingly complex, making it a challenge to create computational water models capable of reproducing the rich behavior of real water but also sufficiently efficient to allow exploration of rare events like ice nucleation. However, it is a worthwhile effort because Molecular Dynamics (MD) simulations of ice formation on the molecular scale can help reveal the fundamental mechanisms behind ice formation that have been elusive to date. In this talk, I will briefly discuss experiments carried out at MTU that serve as motivation to study ice nucleation under negative pressure conditions, and then I will compare two MD water models in terms of their ability to accurately represent the homogeneous freezing response to pressure changes. We propose that a water model with a more accurate representation of the density difference between water and ice (the density anomaly) will also provide a more accurate representation of the change in ice nucleation rate as a function of pressure. This work is a preliminary step in my ongoing project to assess the importance of internal pressure fluctuations on the freezing of supercooled water droplets.
Sambhawana Sharma [Co-Advisors: Dr. Dongyan Zhang, Dr. Yoke Khin Yap] will present:
Exploring the use of Boron Nitride Dots for Photovoltaic Application
Sunlight is an important source of green energy. One can use solar cells (SC) to convert photon energy into electricity. The expensive mono-crystalline silicon is a popular SC materials, but has a less favorable band gap of 1.1 eV, resulting in a theoretical Shockley Queisser Efficiency Limit of 32%. Practically, commercial Si solar cells produce 18-26% conversion efficiency. Because of the fundamental limits of Si, various materials with larger band gap are being explored for SC application including GaAs and perovskites thin films as well as CdSe quantum dots. It is to be noted that perovskite undergoes photochemical degradation, while CdSe and GaAs are toxic. On the other hand, hexagonal Boron Nitride (h-BN) are wide bandgap (6 eV) and non-toxic. Here we explore the synthesis of zero-dimensional h-BN (BN dots) to reduce the band gap into the visible range by creating intra-band states. Our results suggest that BN dots have tunable optoelectronic properties and absorb visible lights within the solar spectrum. This makes BN dots a promising candidate for SC application.
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