Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session B10: Advances in Thermal Energy Conversion for Energy ApplicationsFocus Recordings Available
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Sponsoring Units: GERA Chair: Jiamian Hu Room: McCormick Place W-181A |
Monday, March 14, 2022 11:30AM - 12:06PM |
B10.00001: Materials, Optics, and Thermodynamics of Ultra-high Temperature Thermophotovoltaic Device Invited Speaker: Jeremy N Munday Over the past several decades, a number of photovoltaic (PV) technologies have been proposed and advanced to help meet the world's energy demand. Thermophotovoltaics (TPV) uses a photovoltaic solar cell that is aimed at a hot source that is at a temperature which is lower than that of the sun. In principle, the route can be more efficient that traditional solar PV but is limited by both the operating bandgap of the solar cell (typically low bandgap materials are used) and the temperature and spectrum of the hot body emitter. In this talk, I will describe our recent work using ultra-high melting point materials for the emitter that can enable high efficiency TPV through the design of custom emitters that can operate at temperatures above 1500C. |
Monday, March 14, 2022 12:06PM - 12:18PM |
B10.00002: Thickness dependent thermal conductivity of Zinc Selenide (ZnSe) – A combined Frequency Domain thermoreflectance and first principles study Roshan Sameer Annam, Rajmohan Muthaiah, Jivtesh Garg Heat dissipation in nanostructures is critical as we reduce the system size in order to improve the system performance and reliability. In this study, we are reporting the length dependence thermal conductivity(k) of zinc-blende Zinc-Selenide (ZnSe) between 10 nm and 10000 nm. We measure the k of bulk Zinc-Selenide using Frequency Domain Thermoreflectance (FDTR) as well First principles calculations. This experimental method utilizes optical pump-probe technique which comprises of a pump laser, which is provides the heat to material under study and probe laser which measures the corresponding change in the temperature as function of the changing reflectivity of the material being heated by the continuous wave pump laser. The measurement is done by fitting the measured the phase lag, induced by the thermoreflective response of the material φ = φpump - φprobe to the phase lag that is measured using the 2D diffusion model, using various input parameters such as transducer thickness, thermal properties of the thin film metal transducer and the effective spot size of the probe beam that was measured during the experiment. Thermal conductivity of bulk ZnSe through FDTR measurement is 18 Wm-1K-1 which is in good agreement with the first principles calculations. Based on an agreement between FDTR and first principles computations, we are reporting the thickness (L=10 nm- 10000nm) dependent thermal conductivity of ZnSe. At nanometer length (L=100 nm), k of 7.08 Wm-1K-1 shows that ZnSe will be a candidate material for thermal interface materials. |
Monday, March 14, 2022 12:18PM - 12:30PM Withdrawn |
B10.00003: Electronic Topological Transition as a Route to Improve Thermoelectric Performance in Bi0.5Sb1.5Te3 Fengxian Bai, Jun Mao, Qian Zhang, Xiao-Jia Chen The electronic structure near the Fermi surface determines the electrical properties of the materials, which can be effectively tuned by external pressure. Bi0.5Sb1.5Te3 is a p-type thermoelectric material which holds the record high figure of merit at room temperature. Here we examine whether the figure of merit of this model system can be further enhanced through some external parameter. With the application of pressure, we surprisingly find the power factor of this material exhibits λ behavior with a high value of 4.8 mW m−1K−2 at pressure of 1.8 GPa. Such an enhancement is found to be driven by pressure-induced electronic topological transition, which is revealed by multiple techniques. Together with a low thermal conductivity of about 0.89 W m−1K−1 at the same pressure, a figure of merit of 1.6 is achieved at room temperature, which is the record high value for any known p-type thermoelectric materials discovered so far. The results and findings highlight the electronic topological transition as a new route for improving the thermoelectric properties. |
Monday, March 14, 2022 12:30PM - 12:42PM |
B10.00004: Silicon: A Revenant Thermoelectric Material for Energy Autonomous Integrated Circuits Mark Lee, Ruchika Dhawan, Gangyi Hu, Hari P Panthi, Hal Edwards Si integrated circuits (ICs) for internet-of-things (IoT) electronics must carry an energy source when embedded in dark and inaccessible environments. Microelectronic thermoelectric generators (µTEGs) can provide such energy autonomy from a thermal gradient. Most research on TE technology focuses on high ZT materials, which often contain toxic or expensive elements incompatible with Si IC processing. We report on Si-based µTEGs fabricated on a standard Si IC process line. Although Si has poor ZT, these µTEGs generate power per area per square of temperature difference, ∆T, > 80 µWcm–2K–2, better than most high ZT TEGs. Our Si µTEGs generate voltages > 1.5 V with > 1 µA current using ∆T ~ 20 °C, sufficient to energize existing IoT ICs. These µTEGs can be integrated on-chip with the ICs they support. Our approach applies device physics to optimize power and voltage generated per area, rather than efficiency. This exploits the ability of Si processing to fabricate thermopiles with a large number of TE elements in a small area, producing high power and voltage density despite low efficiency per TE element. Results on power and voltage generation and physics-based models for optimizing performance will be presented. |
Monday, March 14, 2022 12:42PM - 12:54PM |
B10.00005: Full Experimental Seebeck Tensor Characterization for (p × n)-Type Transverse Thermoelectrics Juncen Li, Matthew Grayson, Mercouri G Kanatzidis (p × n)-Type transverse thermoelectrics are proposed as a potential thermoelectric material for waste heat harvesting. They can be made into single-leg devices, which can generate high voltage output from small temperature differences with adequate aspect ratios. Such materials are anisotropic, having an ambipolar Seebeck effect with a negative Seebeck coefficient along one direction and positive orthogonal Seebeck, generating a voltage drop perpendicular to an appropriately oriented temperature gradient, hence the name (p × n)-type. However, standard experiments only measured Seebeck coefficients along specific crystal axes, which is, in principle, insufficient to map the full Seebeck tensor of a low symmetry crystal. Here, we report results for an all-in-one measurement set-up for measuring the full Seebeck tensor on one sample with a custom-made apparatus. Experiments on pre-characterized isotropic material confirm this apparatus can accurately determine the 9 independent Seebeck components. Anisotropic van der Pauw measurements can also be integrated into the apparatus to measure the full in-plane anisotropic resistivity tensor on the same sample. Results of Seebeck tensor measurements in known anisotropic materials such as bismuth single crystals will be presented. |
Monday, March 14, 2022 12:54PM - 1:06PM |
B10.00006: Evaluating the index of refraction of thin films at high temperatures for thermophotovoltaic emitters Mariama Rebello, Margaret A Duncan, Tao Gong, M Hossain, Scott McCormack, S Ness, Marina S Leite, Jeremy N Munday In thermophotovoltaics, photovoltaic cells convert heat from a thermal emitter to electricity. One way to obtain high-efficiency devices is to have the emitted spectrum tailored to a solar cell. One way to achieve this is to use a thin film emitter configuration, where one could optimize the geometric configuration. However, the index of refraction of materials is likely to change at ultra-high temperatures, which may change the optimal geometric conditions. In this work, we characterize the index of refraction of various metals and dielectrics at high temperatures. The materials chosen have melting points above 1800ºC. Also, the thermal stability and the mismatch in the thermal expansion coefficient of each material combination are discussed. As a proof of concept, we evaluate the best emitter candidates for five different solar cell technologies. This work can pave the way for high-temperature photonics with a simple emitter design, resulting in higher efficient photoelectronic devices. |
Monday, March 14, 2022 1:06PM - 1:18PM |
B10.00007: Towards Thermoelectric Weaves: Thermal Conductivity of Bi2Te3 Ribbons Using the Suspended 3ω Method. Lawrence A Rhoads, Xueting Yan, Juncen Li, Thomas Douglas, Matthew Grayson Woven thermoelectric devices are important for conformal thermal energy harvesting in systems where traditional, more rigid, thermoelectric generators are not practical. For this purpose, it is necessary to characterize candidate materials for use in thermoelectric weaves. One such candidate is Bi2Te3, a well-researched material with high thermoelectric performance. Normally rigid, Bi2Te3 can be made into thin, flexible ribbons, ideal for our purposes. To that end, we measured the thermal conductivity of thin p-type Bi2Te3 ribbons using the suspended 3ω method. To our knowledge, this has not yet been done for Bi2Te3 in this configuration. We exfoliated these ribbons using a modified scotch-tape method and constructed an integrated measurement platform that allows us to measure all relevant parameters needed to calculate the figure of merit ZT with very little or no modification between measurement set ups. Our measurement of the average thermal conductivity was 4 W/mK, which is much higher than literature values, of order 1.5 W/mK. Improvements in this novel measurement method will therefore be explored in upcoming experiments. In addition to these results, new data on n-type Bi2Te3 ribbons will also be presented. |
Monday, March 14, 2022 1:18PM - 1:30PM |
B10.00008: KMgBi: A Highly Efficient Quasi-2D Thermoelectric Material Bhawna Sahni, Vikram Vikram, Aftab Alam Half Heusler alloys are known to showcase a variety of interesting properties which make them potential candidates for energy applications. Here, we present a first principles study of KMgBi which is a promising candidate for thermoelectric(TE) applications. This compound has been experimentally synthesized in the past [Zhang, X. et al. Phys. Rev. B 2017, 035209 (95)], but has never been studied from TE perspective. The presence of flat bands near valence band edge and strong spin-orbit coupling provide a fertile ground to explore the potential of this material. The lattice thermal conductivity was calculated using the modified Debye Callaway Model which came out to be as low as ≤ 1 W m-1K-1. The energy and temperature dependent relaxation time was calculated carefully taking into account different scattering mechanisms. The system shows a high TE figure of merit ZT ~ 2.68 (for p-type) at ~ 400K temperature. We have further discussed enhancing the TE performance of KMgBi via alloy engineering. With the proposed alloy engineering, we expect at least a 20% enhancement in the TE figure of merit. |
Monday, March 14, 2022 1:30PM - 1:42PM |
B10.00009: Topological phase and thermoelectric properties of bialkali bismuthide compounds (Na, K)2RbBi from first-principles Shahram Yalameha, Zahra Nourbakhsh, Ali Ramazani, Daryoosh Vashaee We employ first-principles calculations to investigate the topological phase and thermoelectric properties of hypothetical bialkali bismuthide compounds (Na, K)2RbBi. The topological phase transitions of these compounds under hydrostatic pressure within GGA-PBE and TB-mBJ approaches are investigated. The topological surface states and Z2 topological index are also calculated. The electronic properties and transport coefficients are obtained using the PBE-GGA and TB-mBJ approaches combined with the Boltzmann transport equation. The relaxation times are calculated using the deformation potential theory to obtain the electronic thermal and electrical conductivity. We find that the compound has significantly large Grüneisen parameters, indicating the strong anharmonic scattering of acoustic phonons leading to very low lattice thermal conductivity. These materials also have a desirable power factor leading to a relatively flat p-type zT over a wide temperature range. We calculate the elastic tensors and phonon dispersions, respectively, and prove their mechanical and dynamical stability, making them good candidates for thermoelectric applications over a broad range of temperatures. |
Monday, March 14, 2022 1:42PM - 1:54PM |
B10.00010: Identification of the soft mode in Na doped PbTe Lan Yu, Jia-Wei Hu, Zi-Yu Cao, Zhifeng Ren, Xiao-Jia Chen As a leading thermoelectric material, PbTe is widely used in energy conversion applications largely due to its intrinsic low bulk thermal conductivity. However, the current phonon scattering mechanisms responsible for its thermal transport properties in the whole temperature region are not sufficient. Here, from Raman scattering, specific heat, thermoelectric transport, as well as Hall effect measurements, a systematic experimental work on p-type Na-PbTe is presented. A transverse optical (TO) mode softening with increasing temperature is observed by Raman scattering below 120 K, which can account for the anomalous behaviour of electrical resistivity, Seebeck coefficient and magnetoresistance. Combining with the constant gap detected by the jump of heat capacity near 120 K, we identify a soft TO mode from Landau theory. The soft TO mode induced an anomalous phonon scattering process in the high temperature zone shows great phonon anharmonicity beyond the conventional three-phonon and four-phonon processes. Our results reveal that the soft TO mode is vital to further suppress lattice thermal conductivity in PbTe to improve energy conversion efficiency. |
Monday, March 14, 2022 1:54PM - 2:06PM |
B10.00011: Ab Initio Study of the Discharge Mechanism of CuO Cathodes Modified with Bi2O3 in Zn/CuO Batteries Krishna Acharya, Nirajan Paudel, Birendra A Magar, Timothy N Lambert, Igor Vasiliev Recent progress in the development of rechargeable alkaline Zn/CuO batteries has generated a high level of interest in the studies of the electrochemical properties of CuO cathodes. Experimental studies have shown a significant influence of Bi2O3 additives on the cyclability of CuO cathodes in Zn/CuO batteries. However, the mechanism of this influence is not completely understood. We apply ab initio methods based on density functional theory to study the mechanism of interaction of Bi2O3 additives with the CuO cathode material. Using the results of our calculations, we examine the structural and chemical changes occurring in CuO and CuO-Bi2O3 cathodes during the battery discharge and investigate the possibility of the formation of Bi- and Cu-containing intermediate phases in the cathode. |
Monday, March 14, 2022 2:06PM - 2:18PM |
B10.00012: Mapping Ion Hopping in Li Super-Ionic Conductors onto Models of Frustrated Magnetism MABRUR AHMED, Yifei Mo, Michael J Lawler Lithium super-ionic conductors are a class of materials with high ionic conductivity and are potential candidates to be used in next-generation all solid-state Li-ion batteries. Recent studies suggested that there may be a relation between the unusually high ionic conductivity in these materials and their frustrated energy landscape. In this paper, we explore the connection between ion transport and frustration using two models inspired by the field of frustrated magnetism, a lattice Coulomb gas model and a soft density model. We use Monte Carlo methods to generate ground state data as well as dynamics data, then employ unsupervised machine learning routines, such as PCA and Diffusion Map, to gain insight into the structure of the state space. Our results show that transport is frustrated due to lattice geometry. |
Monday, March 14, 2022 2:18PM - 2:30PM |
B10.00013: Kirchhoff Thermal Radiation Law Violation via Resonant Absorption in Hybrid Magneto-Optic InAs Guided-Mode-Resonator Structure Komron J Shayegan, Bo Zhao, Yonghwi Kim, Shanhui Fan, Harry Atwater The Kirchhoff thermal radiation law provides an inherent constraint on the ability to harness thermal radiation, requiring that the spectral emissivity and absorptivity are equal and exhibit identical angular distributions for a given polarization. This equality is built on the fundamental assumption that all materials obey Lorentz reciprocity. One class of materials that does not satisfy Lorentz reciprocity, and thus can violate the Kirchhoff law, is magneto-optically-active materials. In this work, we break time-reversal symmetry and reciprocity in degenerately n-type doped magneto-optic InAs with a static magnetic field where light coupling is mediated by a guided-mode-resonator structure whose resonant frequency coincides with the epsilon-near-zero resonance of the doped InAs. Using an Otto scattering configuration, we observe the nonreciprocal absorptive/emissive behavior as a function of magnetic field and scattering angle in the long-wavelength infrared region. Accounting for resonant and nonresonant optical scattering, we reliably model experimental results that violate the Kirchhoff thermal radiation law and discuss direct thermal emission of magneto-optic materials. |
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