Critical role of atomic-scale defect disorders for high-performance nanostructured half-Heusler thermoelectric alloys and their thermal stability

AbstractCurrent and future power systems require chromia-forming alloys compatible with high-temperature CO2. Important questions concerning the mechanisms of oxidation and carburization remain unanswered. Herein we shed light onto these processes by studying the very initial stages of oxidation of Fe22Cr and Fe22Ni22Cr model alloys. Ambient-pressure X-ray photoelectron spectroscopy enabled in situ analysis of the oxidizing surface under 1 mbar of flowing CO2 at temperatures up to 530 °C, while postexposure analyses revealed the structure and composition of the oxidized surface at the near-atomic scale. We found that gas purity played a critical role in the kinetics of the reaction, where high purity CO2 promoted the deposition of carbon and the selective oxidation of Cr. In contrast, no carbon deposition occurred in low purity CO2 and Fe oxidation ensued, thus highlighting the critical role of impurities in defining the early oxidation pathway of the alloy. The Cr-rich oxide formed on Fe22Cr in high purity CO2 was both thicker and more permeable to carbon compared to that formed on Fe22Ni22Cr, where carbon transport appeared to occur by atomic diffusion through the oxide. Alternatively, the Fe-rich oxide formed in low purity CO2 suggested carbon transport by molecular CO2.

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The critical role of materials metrology in engineering

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1987.0057 ◽

1987 ◽

Vol 322 (1567) ◽

pp. 361-372

Keyword(s):

High Performance ◽

Critical Role ◽

Test Procedures ◽

Engineering Structures ◽

Codes Of Practice ◽

Materials Research ◽

Future Technologies ◽

Industrial Needs ◽

Industrial Standards

This paper analyses the critical underpinning role of materials research and testing for contemporary engineering and future technologies. It is obvious that measurements, tests and evaluations of materials and components, i.e. materials metrologies, are crucial to provide the information and data needed to optimize the function of engineering structures. The industrial needs and research trends in materials metrology are reviewed, and recent BAM-developments of measuring techniques for high-technology sectors, like high-temperature technology or high-performance ceramics, are presented. Finally, the relevance of an appropriate metrological base for the establishment of industrial standards, agreed codes of practice and the harmonization of test procedures for the international trade of technical products is discussed.

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Robust procedure for creating and characterizing the atomic structure of scanning tunneling microscope tips

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.8.238 ◽

2017 ◽

Vol 8 ◽

pp. 2389-2395 ◽

Cited By ~ 6

Author(s):

Sumit Tewari ◽

Koen M Bastiaans ◽

Milan P Allan ◽

Jan M van Ruitenbeek

Keyword(s):

Atomic Structure ◽

Scanning Tunneling Microscope ◽

Critical Role ◽

Atomic Layer ◽

Atomic Scale ◽

Scanning Tunneling ◽

Tunneling Microscope ◽

Stm Tips

Scanning tunneling microscopes (STM) are used extensively for studying and manipulating matter at the atomic scale. In spite of the critical role of the STM tip, procedures for controlling the atomic-scale shape of STM tips have not been rigorously justified. Here, we present a method for preparing tips in situ while ensuring the crystalline structure and a reproducibly prepared tip structure up to the second atomic layer. We demonstrate a controlled evolution of such tips starting from undefined tip shapes.

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Critical Role of Monoclinic Polarization Rotation in High-Performance Perovskite Piezoelectric Materials

Physical Review Letters ◽

10.1103/physrevlett.119.017601 ◽

2017 ◽

Vol 119 (1) ◽

Cited By ~ 47

Author(s):

Hui Liu ◽

Jun Chen ◽

Longlong Fan ◽

Yang Ren ◽

Zhao Pan ◽

...

Keyword(s):

High Performance ◽

Piezoelectric Materials ◽

Critical Role ◽

Polarization Rotation

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The Critical Role of the Constant Region in Thermal Stability and Aggregation of Amyloidogenic Immunoglobulin Light Chain

Biochemistry ◽

10.1021/bi101351c ◽

2010 ◽

Vol 49 (45) ◽

pp. 9848-9857 ◽

Cited By ~ 46

Author(s):

Elena S. Klimtchuk ◽

Olga Gursky ◽

Rupesh S. Patel ◽

Kathryn L. Laporte ◽

Lawreen H. Connors ◽

...

Keyword(s):

Thermal Stability ◽

Light Chain ◽

Critical Role ◽

Constant Region ◽

Immunoglobulin Light Chain

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A closed-loop human simulator for investigating the role of feedback control in brain-machine interfaces

Journal of Neurophysiology ◽

10.1152/jn.00503.2010 ◽

2011 ◽

Vol 105 (4) ◽

pp. 1932-1949 ◽

Cited By ~ 99

Author(s):

John P. Cunningham ◽

Paul Nuyujukian ◽

Vikash Gilja ◽

Cindy A. Chestek ◽

Stephen I. Ryu ◽

...

Keyword(s):

Feedback Control ◽

Neural Activity ◽

High Performance ◽

Closed Loop ◽

Critical Role ◽

Healthy Human ◽

Neural Prosthetic ◽

Decoding Algorithms ◽

Current State

Neural prosthetic systems seek to improve the lives of severely disabled people by decoding neural activity into useful behavioral commands. These systems and their decoding algorithms are typically developed “offline,” using neural activity previously gathered from a healthy animal, and the decoded movement is then compared with the true movement that accompanied the recorded neural activity. However, this offline design and testing may neglect important features of a real prosthesis, most notably the critical role of feedback control, which enables the user to adjust neural activity while using the prosthesis. We hypothesize that understanding and optimally designing high-performance decoders require an experimental platform where humans are in closed-loop with the various candidate decode systems and algorithms. It remains unexplored the extent to which the subject can, for a particular decode system, algorithm, or parameter, engage feedback and other strategies to improve decode performance. Closed-loop testing may suggest different choices than offline analyses. Here we ask if a healthy human subject, using a closed-loop neural prosthesis driven by synthetic neural activity, can inform system design. We use this online prosthesis simulator (OPS) to optimize “online” decode performance based on a key parameter of a current state-of-the-art decode algorithm, the bin width of a Kalman filter. First, we show that offline and online analyses indeed suggest different parameter choices. Previous literature and our offline analyses agree that neural activity should be analyzed in bins of 100- to 300-ms width. OPS analysis, which incorporates feedback control, suggests that much shorter bin widths (25–50 ms) yield higher decode performance. Second, we confirm this surprising finding using a closed-loop rhesus monkey prosthetic system. These findings illustrate the type of discovery made possible by the OPS, and so we hypothesize that this novel testing approach will help in the design of prosthetic systems that will translate well to human patients.

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The Transmittance Modulation of ZnO/Cu/ZnO Transparent Conductive Electrodes Prepared on Glass Substrates

Materials ◽

10.3390/ma13183916 ◽

2020 ◽

Vol 13 (18) ◽

pp. 3916

Author(s):

Dooho Choi

Keyword(s):

Visible Light ◽

Sheet Resistance ◽

High Performance ◽

Critical Role ◽

Optoelectronic Devices ◽

Light Transmittance ◽

Glass Substrates ◽

Average Transmittance ◽

Optimized Conditions

With the explosive development of optoelectronic devices, the need for high-performance transparent conductive (TCE) electrodes for optoelectronic devices has been increasing accordingly. The two major TCE requirements are (1) visible light average transmittance higher than 80% and (2) sheet resistance lower than 10 Ω/sq. In this study, we investigated the critical role of the top and bottom ZnO thicknesses for the ZnO/Cu/ZnO electrodes prepared on glass substrates. It was shown that the required Cu thickness to meet the conductivity requirement is 8 nm, which was fixed and then the thicknesses of the top and ZnO layers were independently varied to experimentally determine the optimized conditions for optical transparency. The thicknesses of the top and bottom ZnO layers were both found to significantly affect the peak transmittance as well as the average visible light transmittance. The ZnO/Cu/ZnO electrode exhibits peak and average transmittance of 95.4% and 87.4%, excluding the transmittance of glass substrates, along with a sheet resistance of 9.7 Ω/sq, with a corresponding Haacke’s figure of merit (φH=Tave10Rs) of 0.064, which exceeds the reported value for the ZnO/Cu/ZnO electrodes, manifesting the need of experimental optimization in this study.

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High-Resolution Measurement of Molecular Internal Polarization Structure by Photoinduced Force Microscopy

Applied Sciences ◽

10.3390/app11156937 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6937

Author(s):

Hidemasa Yamane ◽

Nobuhiko Yokoshi ◽

Hajime Ishihara

Keyword(s):

High Resolution ◽

Single Molecule ◽

Near Field ◽

Critical Role ◽

Single Molecules ◽

Atomic Scale ◽

Metallic Surface ◽

Metallic Surfaces ◽

Force Microscopy

Near-field interactions between metallic surfaces and single molecules play an essential role in the application of metamaterials. To reveal the near-field around a photo-irradiated single molecule on the metallic surface, high-resolution photo-assisted scanning microscopy is required. In this study, we theoretically propose photoinduced force microscopy (PiFM) measurements of single molecules at the atomic resolution. For experimental demonstration, we performed a numerical calculation of PiFM images of various transition states, including optical forbidden transitions, and interpreted them in terms of the interaction between the molecular internal polarization structures and localized plasmon. We also clarified the critical role of atomic-scale structures on the tip surface for high-resolution PiFM measurements.

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