Bulletin of the American Physical Society
Four Corners Section 2022 Meeting
Volume 67, Number 14
Friday–Saturday, October 14–15, 2022; Albuquerque, New Mexico
Session E05: Materials I |
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Chair: Heinz Nakotte, New Mexico State University Room: UNM PAIS 1140 |
Friday, October 14, 2022 2:30PM - 2:54PM |
E05.00001: High-throughput Identification of Stable 2D Janus-Bulk Material Heterostructures Invited Speaker: Arunima Singh Two-dimensional (2D) Janus materials possess unique properties such as finite out-of-plane dipole moments, Rashba effect, strongly bound excitons, and strong |
Friday, October 14, 2022 2:54PM - 3:06PM |
E05.00002: High Mobility Two-Dimensional Electron Gas in BaSnO3/SrNbO3 Interface Sharad Mahatara, Suresh Thapa, Hanjong Paik, Ryan Comes, Boris Kiefer Two-dimensional electron gases (2DEGs) realized at interfaces offer great promise for high charge carrier concentrations and low-loss charge transport. BaSnO3 (BSO) is well-known for its high mobility due to its Sn-5s dominated conduction band minimum (CBM). Nb4+ with d1 valence configuration in SrNbO3 (SNO) may inject the d1 electron across the interface into the unoccupied Sn-5s states in BSO. In the present study, we use the synergy of ACBN0 computations and experiment to explore the charge transfer and 2DEG formation at BSO/SNO interfaces. The results of the ACBN0 computations confirm the intended Nb-4d to Sn-5s charge transfer. Moreover, the Sn-5s CMB is located up to ~1.2 eV below the Fermi level, corresponding to an excess electron density in BSO of ~1021 cm-3. Our angle-resolved X-ray photoelectron spectroscopy experiments for BSO/SNO interfaces grown by molecular beam epitaxy suggest an even higher electron density of ~4×1021 cm-3. This charge density discrepancy is attributed to a slight overestimation of the bandgap in the computation relative to experiment. In summary, consistency of theory and the experiments shows that BSO/SNO interfaces provide a novel rational materials platform for 2DEG formation and ultra-low loss electron transport. |
Friday, October 14, 2022 3:06PM - 3:18PM |
E05.00003: Electron Yield Measurements of Highly Insulating Granular Samples Related to Charging of Dusty Plasmas Heather Allen, Matthew L Robertson, Thomas Keaton, JR Dennison Lack of reliable electron yield (EY) measurements of highly insulating granular particles due to many experimental complexities have led to a critical knowledge gap for both engineering strategies and basic science issues essential to charging in myriad dusty plasma and space applications. EY measurements are presented, which demonstrate the ability to acquire accurate EY versus incident energy curves with minimal charging effects. Measurements studied different composition non-conductive particulate samples adhered to graphitic carbon conductive substrates, for cubic, spherical, and highly-angular particle shapes with a range particle size from ~1 to ~100 μm. Results for various size particles from 0% to ~100% coverage demonstrated the effectiveness of the dust sample preparation and tests methods. Acquired EY curves showed minimal charging effects, demonstrating our ability to measure EY for very high-yield, highly insulating samples, in contrast to previous results for dust which showed highly suppressed yields due to severe charging effects. The effects of surface roughness porosity, and compactness were investigated through comparison of EY for highly polished single crystal sapphire, rougher microcrystalline Al2O3, and very rough and porous layers of granular alumina; maximum yield decreased from >15 to ~2.2 as roughness increased with minimal change in shape of the yield curves and energy at maximum yield. Applications of these results to issues surrounding mitigation of electrostatic charging of lunar dust are discussed. |
Friday, October 14, 2022 3:18PM - 3:30PM |
E05.00004: Effect of Fluence on Electron Deposited Charge Distributions in Polytetrafluoroethylene Zachary J Gibson, John R Dennison, Virginie Griseri Charge embedded in highly-insulating dielectric polymers such as polytetrafluoroethylene (PTFE) are important in many applications from high voltage DC power transmission to spacecraft charging. Fluence of the incident electrons can change the resulting charge distribution in potentially unexpected ways. While the magnitude of the measured charge distribution will obviously increase with increased fluence, the shape of the distribution may also change. This can be due to effects such as radiation induced conductivity, damage to material, and interactions between embedded and incident electrons. To test the effects of fluence on charge deposition in PTFE, several samples of 150 µm thick PTFE were irradiated with varying fluence. This was achieved with an 80 keV monoenergetic electron beam with flux ranging from 0.3-1 nA/cm2 flux for 2-8 minutes resulting in fluence from 36-480 nC/cm2. The embedded charge distributions were then measured in ambient conditions with a pulsed electroacoustic (PEA) system. The measurements were then compared to show the differences in the resulting charge distributions. The effects of varying fluence include changes in the shape, magnitude, position, and introduction of positive charge in the measured distributions. |
Friday, October 14, 2022 3:30PM - 3:42PM |
E05.00005: Study of Electronic and Thermoelectric Properties of CaNiO3 Perovskite Bhishm S Joshi, Sharad Mahatara, Harikrishnan S Nair, Madhav P Ghimire, Boris Kiefer Perovskite structured materials find a wide range of technological application, from solar cells, to catalysts, and thermoelectricity. In this study, we investigate the electronic, magnetic, and thermoelectric properties of CaNiO3, a transition metal perovskite, using all-electron and pseudopotential density-functional-theory. Both meta-GGA and ACBN0 functional predict that the ground state of CaNiO3 is orthorhombic with a narrow bandgap of Eg~0.3-0.5 eV. The predicted absence of magnetism is consistent with a Ni+4 oxidation state, as well as the observed opening of a bandgap. In contrast, our ACBN0 computations predict that cubic CaNiO3 is a ferromagnetic metal. Thus, our preliminary results show that the bandgap opening, and disappearance of magnetism is caused by the continuous octahedral rotations that connect the cubic and orthorhombic structure. The meta-GGA computations predict thermoelectric figure of merit of CaNiO3, ZT=1.08 at 300K, 66% larger than that of double perovskite CaPd3B4O12 (B = Ti, V) reported previously. At T=1200 K, we find ZT=0.57, comparable to other thermoelectric materials. Therefore, our results predict that CaNiO3 is an excellent candidate for thermoelectric applications at room temperature as well as high temperatures. |
Friday, October 14, 2022 3:42PM - 3:54PM |
E05.00006: DC Conductivity of Platinum From Ab Initio Simulation Meghan Lentz, Joshua P Townsend, Kyle R Cochrane Platinum (Pt) is a highly unreactive transition metal with a high melting point. Alongside its everyday uses, Pt’s properties make it desirable for high pressure shock experiments at Sandia National Laboratories’ (SNL) Z Pulsed Power facility. Previous literature [Earth Planet. Sci. Lett., 544 (2020), p. 116380] have reported electrical conductivity values for Pt at ambient pressure near the melting point. Here we present Kubo Greenwood (KG) electrical conductivity convergence studies for Pt at ambient conditions, as well as a comparison of the conductivity at temperatures near Pt’s melt with those reported. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. |
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