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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Ionic Liquid Gating Control of Spin Reorientation Transition and Switching of Perpendicular Magnetic Anisotropy

Electric field (E–field) modulation of perpendicular magnetic anisotropy (PMA) switching, in an energy–efficient manner, is of great potential to realize magnetoelectric (ME) memories and other ME devices. Voltage control of the spin–reorientation transition (SRT) that allows the magnetic moment rotating between the out–of–plane and the in–plane direction is thereby crucial. In this work, a remarkable magnetic anisotropy field change up to 1572 Oe is achieved under a small operation voltage of 4 V through ionic liquid (IL) gating control of SRT in Au/[DEME]+[TFSI] – /Pt/(Co/Pt) 2 /Ta capacitor heterostructures at room temperature, corresponding to a large ME coefficient of 378 Oe V –1 . As revealed by both ferromagnetic resonance measurements and magnetic domain evolution observation, the magnetization can be switched stably and reversibly between the out–of–plane and in–plane directions via IL gating. The key mechanism, revealed by the first–principles calculation, is that the IL gating process influences the interfacial spin–orbital coupling as well as net Rashba magnetic field between the Co and Pt layers, resulting in the modulation of the SRT and in–plane/out–of–plane magnetization switching. In conclusion, this work demonstrates a unique IL–gated PMA with large ME tunability and paves a way toward IL gating spintronic/electronic devices such as voltage tunable PMA memories.

36 MATERIALS SCIENCE↗
NASA NTRS1989

Clean Room Apparel

American Hospital Supply Corporation (AHSC), Baxter Healthcare Corporation's predecessor, used the NASA informational base on contamination control technology to improve industrial contamination control technology. When a study determined that microscopic body particles escaping through tiny "windows" in woven garments worn by workers were the greatest source of contamination, AHSC developed TYVEK. This non-woven material filters 99% of all particulate matter larger than half a micron. Baxter Healthcare added a polyimide coating which seals and ties down any loose fibers, providing greater durability. Stress points along seams have been minimized to make the garment almost tearproof. Micro-Clean 212 garments are individually packaged and disposable.

Source record↗
DOE OSTI2017

Deterministic and robust room-temperature exchange coupling in monodomain multiferroic BiFeO 3 heterostructures

Exploiting multiferroic BiFeO 3 thin films in spintronic devices requires deterministic and robust control of both internal magnetoelectric coupling in BiFeO 3 , as well as exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer. Previous reports utilized approaches based on multi-step ferroelectric switching with multiple ferroelectric domains. Because domain walls can be responsible for fatigue, contain localized charges intrinsically or via defects, and present problems for device reproducibility and scaling, an alternative approach using a monodomain magnetoelectric state with single-step switching is desirable. Here we demonstrate room temperature, deterministic and robust, exchange coupling between monodomain BiFeO 3 films and Co overlayer that is intrinsic (i.e., not dependent on domain walls). Direct coupling between BiFeO 3 antiferromagnetic order and Co magnetization is observed, with ~90° in-plane Co moment rotation upon single-step switching that is reproducible for hundreds of cycles. Finally, this has important consequences for practical, low power non-volatile magnetoelectric devices utilizing BiFeO 3 .

36 MATERIALS SCIENCE↗
DOE OSTI2026

350 ps Ultrafast room-temperature scintillation realized on CsPbBr 3 -based single crystals via Br 2 over-doping

Ultrafast scintillators are essential for next-generation radiation detection, positron emission tomography, and high-speed medical imaging. All-inorganic CsPbBr 3 perovskites are attractive candidates because of their high stopping power, and excellent optical quality, yet their long carrier lifetimes result in slow scintillation responses on the order of hundreds of nanoseconds. Here, we demonstrate that controlled over-doping with Br 2 produces CsPbBr 3.03 single crystals with sub-nanosecond scintillation at room temperature while preserving crystal quality. Single crystals grown by the Bridgman method exhibit high transparency and maintain the orthorhombic perovskite structure. Br 2 over-doping induces a slight lattice expansion (about 0.42% increase in unit-cell volume) while maintaining the orthorhombic perovskite phase and high optical transparency. Optical absorption reveals a slight redshift of the absorption edge after Br 2 introduction, indicating a modified defect landscape. Time-resolved photoluminescence and radioluminescence measurements show that Br 2 doping creates dense and efficient recombination centers that reduce the scintillation decay time from more than 100 ns in undoped crystals to 350 ps under 5.486 MeV α-particle excitation, and the scintillation decay time decreases by two orders of magnitude. The doped crystals also achieve a spatial resolution of 12 lp mm −1 in X-ray imaging. These results reveal a defect-engineering route for achieving ultrafast scintillation in halide perovskites and highlight the potential of Br 2 -modified CsPbBr 3 for fast timing applications.

Li, Zongxiao [Chinese Academy of Sciences (CAS), N↗
NASA NTRS2014

Firing Room Remote Application Software Development

The Engineering and Technology Directorate (NE) at National Aeronautics and Space Administration (NASA) Kennedy Space Center (KSC) is designing a new command and control system for the checkout and launch of Space Launch System (SLS) and future rockets. The purposes of the semester long internship as a remote application software developer include the design, development, integration, and verification of the software and hardware in the firing rooms, in particular with the Mobile Launcher (ML) Launch Accessories subsystem. In addition, a Conversion Fusion project was created to show specific approved checkout and launch engineering data for public-friendly display purposes.

Pathways↗
NASA NTRS2015

Firing Room Remote Application Software Development

The Engineering and Technology Directorate (NE) at National Aeronautics and Space Administration (NASA) Kennedy Space Center (KSC) is designing a new command and control system for the checkout and launch of Space Launch System (SLS) and future rockets. The purposes of the semester long internship as a remote application software developer include the design, development, integration, and verification of the software and hardware in the firing rooms, in particular with the Mobile Launcher (ML) Launch Accessories (LACC) subsystem. In addition, a software test verification procedure document was created to verify and checkout LACC software for Launch Equipment Test Facility (LETF) testing.

Pathways↗
NASA NTRS2013

A Nanostructured Composites Thermal Switch Controls Internal and External Short Circuit in Lithium Ion Batteries

A document discusses a thin layer of composite material, made from nano scale particles of nickel and Teflon, placed within a battery cell as a layer within the anode and/or the cathode. There it conducts electrons at room temperature, then switches to an insulator at an elevated temperature to prevent thermal runaway caused by internal short circuits. The material layer controls excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect

McDonald, Robert C.↗
DOE OSTI2020

Performance Evaluation of High-Temperature Ultrasonic Communication System

Ultrasonic communication is a technique that allows transmitting information through a solid material such as tubes or bars using high-frequency elastic waves. The communication channels often extend into a high-temperature range in the field of power, oil, or nuclear industry. When the temperature is taken into consideration, the ultrasonic wave propagation through the solid channel is complex and unpredictable. It is necessary to study the influence of temperature on the ultrasonic guided wave to improve ultrasonic communication. In this study, a temperature control system is assembled to adjust the temperature of a steel pipe channel ranging from room temperature to 150 degrees C. The temperature performance evaluation is conducted to estimate the signal-to-noise ratio (SNR) and bit error rate (BER) of transferring the ultrasonic signal. The work aims to develop a reliable ultrasonic communication system in a high-temperature environment. The system temperature can be maintained at 150 degrees C and the LiNbO3 transducers are used as transmitters and receivers. No power amplifier is used in the communication system. The high-temperature ultrasonic communication system (HT-UCS) is feasible at 150 degrees C and can achieve a bit rate of 10 kbps without any error.

HT-UCS↗
DOE OSTI2024

Switching the spin cycloid in BiFeO3 with an electric field

Abstract Bismuth ferrite (BiFeO 3 ) is a multiferroic material that exhibits both ferroelectricity and canted antiferromagnetism at room temperature, making it a unique candidate in the development of electric-field controllable magnetic devices. The magnetic moments in BiFeO 3 are arranged into a spin cycloid, resulting in unique magnetic properties which are tied to the ferroelectric order. Previous understanding of this coupling has relied on average, mesoscale measurements. Using nitrogen vacancy-based diamond magnetometry, we observe the magnetic spin cycloid structure of BiFeO 3 in real space. This structure is magnetoelectrically coupled through symmetry to the ferroelectric polarization and this relationship is maintained through electric field switching. Through a combination of in-plane and out-of-plane electrical switching, coupled with ab initio studies, we have discovered that the epitaxy from the substrate imposes a magnetoelastic anisotropy on the spin cycloid, which establishes preferred cycloid propagation directions. The energy landscape of the cycloid is shaped by both the ferroelectric degree of freedom and strain-induced anisotropy, restricting the spin spiral propagation vector to changes to specific switching events.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Impact of substrates and quantum effects on exciton line shapes of 2D semiconductors at room temperature

Exciton resonances in monolayer transition-metal dichalcogenides (TMDs) provide exceptionally strong light–matter interaction at room temperature. Their spectral line shape is critical in the design of a myriad of optoelectronic devices, ranging from solar cells to quantum information processing. However, disorder resulting from static inhomogeneities and dynamical fluctuations can significantly impact the line shape. Many recent works experimentally evaluate the optical properties of TMD monolayers placed on a substrate and the line shape is typically linked directly to the material’s quality. Here, we highlight that the interference of the substrate and TMD reflections can strongly influence the line shape. We further show how basic, room-temperature reflection measurements allow investigation of the quantum mechanical exciton dynamics by systematically controlling the substrate reflection with index-matching oils. By removing the substrate contribution with properly chosen oil, we can extract the excitonic decay rates including the quantum mechanical dephasing rate. The results provide valuable guidance for the engineering of exciton line shapes in layered nanophotonic systems.

2D semiconductor↗
NASA NTRS1975

Significance of biorhythms in space flight

Evidence is presented that the most important factor in the maintenance of optimal health and performance is the stability of the relationship of one body rhythm to another. The effect of social interaction on performance, well-being, and physiological rhythm synchrony was investigated. Three groups of healthy males, ages 21 to 25, were confined in rooms (3.4 by 5.2 meters (11 by 17 feet)) for a total period of 105 days. Two of the groups were in rooms in which the environment could be regulated. The third group served as the control group and was exposed to ambient experimental conditions. The confined subjects were exposed for periods to several days either to 16 hours of light and 8 hours of dark, or to continuous light at a light intensity of 161 lm/sq m (15 foot-candles). The confined subjects were deprived of all time cues, and meals were ad libitum. The subjects were observed throughout the study by a video camera and were scored for activity. Communications were limited to meal and sample-collection information, and meals and samples were passed through a two-way hatch. Rectal temperature and heart rate (HR) were sampled every 30 minutes by telemetry throughout the study. Results are presented.

Winget, C. M.↗
NASA NTRS1975

Digital control of high-intensity acoustic testing

A high intensity acoustic test system is reported that consists of a reverberation room measuring 18 feet wide by 21 feet long by 26 feet high, with an internal volume of 10,900 cubic feet. The room is rectangular in shape. Acoustic energy is supplied through two 50-Hz cutoff exponential horns about 12 feet long. Each of the two horns has two transducers rated at 4000 acoustic watts each. A gaseous nitrogen supply is used to supply the energy. The equalized electrical signal is corrected by a circuit designed to compensate for the transducer nonlinearity, then fed into one channel of a phase linear power amplifier, then into the transducer. The amplifiers have been modified to increase their reliability. The acoustic energy in the room is monitored by six B and K 1/2-inch condenser microphones. The electrical signal from each microphone is fed into a six channel real time averager to give a spatial average of the signals.

Slusser, R. A.↗
NASA NTRS1976

In situ investigation of the mobility of small gold clusters on cleaved MgO surfaces

The mobility of small clusters of gold (about 10 A in diameter) on electron-beam-cleaved MgO surfaces was studied by in situ transmission electron microscopy under controlled vacuum and temperature conditions. During the first 10 min following a deposition at room temperature, over 10 per cent of the crystallites moved over short distances (about 20 A) discontinuously, with a velocity greater than 150 A/sec. Eighty per cent of the mobility events were characterized by the avoidance of proximity of other crystallites, and this was tentatively explained as the result of repulsive elastic forces between the interacting crystallites.

Metois, J. J.↗
NASA NTRS1979

Design and development of a trace contaminant removal canister for Spacelab

The paper describes the overall approach used by NASA-MSFC to design and develop a trace contaminant removal canister for Spacelab. The elements of this approach include the establishment of a trace contaminant load model, analysis and testing to define a preliminary design, development testing to verify the adequacy of the selected design, and testing to define a suitable canister location in the transfer tunnel ventilation system. The canister utilizes a catalyst material which is effective in removing carbon monoxide at room temperature, as well as plain and acid treated charcoal. The canister alone will control all contaminants in the load model below their maximum allowable concentration (MAC) levels without assistance from the baseline environmental control system (ECS) except for methyl alcohol and ammonia.

Ray, C. D.↗