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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Flexible, FEP-Teflon covered solar cell module development

Techniques and equipment were developed for the large scale, low-cost fabrication of lightweight, roll-up and fold-up, FEP-Teflon encapsulated solar cell modules. Modules were fabricated by interconnecting solderless single-crystal silicon solar cells and heat laminating them at approximately 300 C between layers of optically clear FEP and to a loadbearing Kapton substrate sheet. Modules were fabricated from both conventional and wraparound contact solar cells. A heat seal technique was developed for mechanically interconnecting modules into an array. The electrical interconnections for both roll-up and fold-up arrays were also developed. The use of parallel-gap resistance welding, ultrasonic bonding, and thermocompression bonding processes for attaching interconnects to solar cells were investigated. Parallel-gap welding was found to be best suited for interconnecting the solderless solar cells into modules. Details of the fabrication equipment, fabrication processes, module and interconnect designs, environmental test equipment, and test results are presented.

Rauschenbach, H. S.↗
NASA NTRS1994

Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

Vered, R.↗
NASA NTRS1997

Investigation of Teflon FEP embrittlement on spacecraft in low earth orbit

Teflon(TM) fluorinated ethylene-propylene (FEP) is used on the exterior of spacecraft surfaces in the low earth orbit environment for thermal control. Silverized or aluminized Teflon(TM) FEP used in the Long Duration Exposure Facility (LDEF) and the Hubble Space Telescope (HST) provided evidence of the low earth orbit environments. Samples from the LDEF and HST were evaluated for solar induced embrittlement and for synergistic effects of solar degradation and atomic oxygen.

deGroh, Kim K.↗
NASA NTRS1998

Degradation of Hubble Space Telescope Metallized Teflon(trademark) FEP Thermal Control Materials

The mechanical and optical properties of the metallized Teflon Fluorinated Ethylene Propylene (FEP) thermal control materials on the Hubble Space Telescope (HST) have degraded over the seven years the telescope has been in orbit. Astronaut observations and photographic documentation from the Second Servicing Mission revealed severe cracks of the multi-layer insulation (MLI) blanket outer layer in many locations around the telescope, particularly on solar facing surfaces. Two samples, the outer Teflon FEP MLI layer and radiator surfaces, were characterized post- mission through exhaustive mechanical, thermal, chemical, and optical testing. The observed damage to the thermal control materials, the sample retrieval and handling, and the significant changes to the radiator surfaces of HST will be discussed. Each of these issues is addressed with respect to current and future mission requirements.

Hansen, Patricia A.↗
DOE OSTI2020

Materials Data on FeP by Materials Project

FeP is Modderite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Fe3+ is bonded to six equivalent P3- atoms to form a mixture of distorted edge, face, and corner-sharing FeP6 octahedra. The corner-sharing octahedra tilt angles range from 43–57°. There are a spread of Fe–P bond distances ranging from 2.22–2.33 Å. P3- is bonded in a 6-coordinate geometry to six equivalent Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(FeP)2 by Materials Project

U(FeP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U is bonded in a 8-coordinate geometry to eight equivalent Fe and eight equivalent P atoms. All U–Fe bond lengths are 3.01 Å. All U–P bond lengths are 2.93 Å. Fe is bonded to four equivalent U and four equivalent P atoms to form a mixture of distorted edge, face, and corner-sharing FeU4P4 tetrahedra. All Fe–P bond lengths are 2.23 Å. P is bonded in a 9-coordinate geometry to four equivalent U, four equivalent Fe, and one P atom. The P–P bond length is 2.32 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li(FeP)2 by Materials Project

Li(FeP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Li1+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All Li–P bond lengths are 2.90 Å. Fe+2.50+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.19 Å. P3- is bonded in a 9-coordinate geometry to four equivalent Li1+, four equivalent Fe+2.50+, and one P3- atom. The P–P bond length is 2.29 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(FeP)2 by Materials Project

K(FeP)2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All K–P bond lengths are 3.40 Å. Fe+2.50+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.19 Å. P3- is bonded in a 4-coordinate geometry to four equivalent K1+ and four equivalent Fe+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs(FeP)2 by Materials Project

Cs(FeP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Cs1+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All Cs–P bond lengths are 3.70 Å. Fe+2.50+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.19 Å. P3- is bonded in a 4-coordinate geometry to four equivalent Cs1+ and four equivalent Fe+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Observation of Giant Optical Linear Dichroism in a Zigzag Antiferromagnet FePS 3

Direct optical probing of the antiferromagnetic order parameter in atomically thin samples is challenging, for example, via magneto-optical spectroscopy, due to the lack of net magnetization. Here, we report zigzag-antiferromagnetism (AFM) induced optical linear dichroism (LD) in layered transition-metal thiophosphate FePS3 down to the monolayer limit. The observed LD is giant despite having the optical wave vector parallel to the Neel vector. The LD is at least one order of magnitude larger than those reported in other antiferromagnetic systems, where the optical wave vector is orthogonal to the Neel vector. The large LD enables the probe of 60 degrees orientated zigzag-AFM domains. The optical anisotropy in FePS 3 originates from an electronic anisotropy associated with the zigzag direction of the AFM order and is independent of the spin-pointing direction. Furthermore, our findings point to a new optical approach for the investigation and control of zigzag or stripe magnetic order in strongly correlated systems.

2D magnet↗
DOE OSTI2025

Tuning magnetism in Ising-type van der Waals magnet FePS 3 by lithium intercalation

Recently, layered transition metal thiophosphate MPX 3 (M = transition metals, X = S or Se) have gained significant attention because of their rich magnetic, optical, and electronic properties. Specifically, the diverse magnetic structures and the robustness of magnetism in the two-dimensional (2D) limit have made them prominent candidates to study 2D magnetism. Numerous efforts such as substitutions and interlayer intercalations have been adopted to tune the magnetic properties of these materials, which has greatly deepened the understanding of the underlying mechanisms that govern the properties. In this work, we focus on modifying the magnetism of Ising-type antiferromagnet FePS 3 using electrochemical lithium intercalation. Furthermore, our work demonstrate the effectiveness of electrochemical intercalation as a controllable tool to modulating magnetism, including tuning magnetic ordering temperature and inducing low temperature spin-glass state, offering an approach for implementing this material into applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1973

Spaceflight performance of silver coated FEP Teflon as a thermal control surface on the IMP-1 spacecraft

A second surface mirror type coating, vapor deposited silver on FEP Teflon, was used as a thermal control surface for one of the experiments aboard the Imp-I spacecraft. This coating was selected to obtain the low operating temperature required for this experiment. Initial flight temperature of this thermal control surface was -70.5 C, very close to the predicted value of -73 C and at a very satisfactory level. Since temperatures within the spacecraft interior are not at this desired low level, the detectors had to be mounted exterior to the spacecraft with a good view of space, preferably in an area shaded from sunlight. When this latter preference proved unobtainable, the detectors were mounted on an aluminum plate located on the exterior of the spacecraft, parallel to the spin axis but rotating about the solar vector. The mounting plate was approximately 6.5 inches by 7.5 inches by 0.125 inches thick. To achieve the desired temperature level with the mounting plate in such a location, the thermal design had to minimize not only the effects of the relatively warm spacecraft environment but also the effects of the incident solar energy.

Hoffman, R. H.↗
NASA NTRS1975

FEP-TEFLON encapsulated solar cell modules Further progress

A progress report, starting with November 1973, is given in the design, development, and performance of lightweight flexible FET (Fluorinated Ethylene Propylene) encapsulated solar cell modules intended to form standardized building blocks for large roll-up or fold-up solar cell blankets with performances on the order of 100 W/sq m and 80 W/kg in near space. It is shown that interconnected FEP encapsulated modules of advanced design can withstand all typical ground handling, assembly, storage, and launch conditions, and are well suited for high-power space applications.

Rauschenbach, H. S.↗
NASA NTRS1978

Selection standard for FEP films for solar energy

Purple fluorocarbon ethylene propylene (FEP) films are more efficient due to low absorptance. Designers seeking to improve coatings quantify this effect and devise simple screening test based on transmittance of films.

Reed, M. W.↗