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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Interstellar material in the solar system

All the substance of the Earth and other terrestrial planets once existed in the form of interstellar grains and gas. A major aspect of solar system formation (and undoubtedly of star formation generally) is the complex series of processes that converted infalling interstellar grains into planets. A cryptic record of these processes is preserved in certain samples of planetary materials, such as chondritic meteorites, that were preserved in a relatively unchanged form since the beginning. It is to be expected that some of these primitive materials might contain or even consist of preserved presolar interstellar grains. The identification and study of such grains, the ancestors of our planetary system, is a matter of intense interest. Types of primitive material accessible or potentially accessible, and component of or relationship to presolar interstellar grains are discussed.

Wood, J. A.↗
DOE OSTI2023

A Si-Substituted Spirobifluorene Hole-Transporting Material for Perovskite Solar Cells

Hybrid organic-inorganic perovskite solar cells (PSCs) have shown promise for next-generation photovoltaics. Here, this study presents a simple approach for enhancing the performance and stability of PSCs by substituting the center carbon atom of the common hole transport material (HTM) Spiro-MeOTAD with a silicon atom. This modification, termed Si-Spiro, results in an increased hole mobility. A density functional theory simulation indicates that the enhanced hole mobility is due to the structural change of Si-Spiro. Electron beam-induced current microscopy measurements indicate improved charged extraction at the Si-Spiro/perovskite interface. A power conversion efficiency of 22.5% is achieved in Si-Spiro-based PSCs, outperforming standard Spiro-MeOTAD. Additionally, Si-Spiro-based PSCs demonstrate enhanced stability, maintaining over 90% of performance over 120 h of one-sun operation. Depth-profiling X-ray photoelectron spectroscopy revealed that Si-Spiro effectively blocks metal ion migration, which contributes to its enhanced stability. The findings suggest that Si-Spiro could be promising a HTM for high-performing, stable PSCs.

14 SOLAR ENERGY↗
NASA NTRS1992

Volatiles in interplanetary dust particles - A review

The paper presents a review of the volatiles found within interplanetary dust particles. These particles have been shown to represent primitive material from early in the solar system's formation and also may contain records of stellar processes. The organogenic elements (i.e., H, C, N, O, and S) are among the most abundant elements in our solar system, and their abundances, distributions, and isotopic compositions in early solar system materials permit workers to better understand the processes operating early in the evolutionary history of solar system materials. Interplanetary dust particles have a range of elemental compositions, but generally they have been shown to be similar to carbonaceous chondrites, the solar photosphere, Comet Halley's chondritic cores, and matrix materials of chondritic chondrites. Recovery and analysis of interplanetary dust particles have opened new opportunities for analysis of primitive materials, although interplanetary dust particles represent major challenges to the analyst because of their small size.

Gibson, Everett K., Jr.↗
DOE OSTI2025

Chemistry of Materials Underpinning Photoelectrochemical Solar Fuel Production

Since its inception, photoelectrochemistry has sought to power the generation of fuels, particularly hydrogen, using energy from sunlight. Efficient and durable photoelectrodes, however, remain elusive. Here we review the current state of the art, focusing our discussion on advances in photoelectrodes made in the past decade. We open by briefly discussing fundamental photoelectrochemical concepts and implications for photoelectrode function. We next review a broad range of semiconductor photoelectrodes broken down by material class (oxides, nitrides, chalcogenides, and mature photovoltaic semiconductors), identifying intrinsic properties and discussing their influence on performance. We then identify innovative in situ and operando techniques to directly probe the photoelectrode|electrolyte interface, enabling direct assessment of structure–property relationships for catalytic surfaces in active reaction environments. We close by considering more complex photoelectrochemical fuel-forming reactions (carbon dioxide and nitrogen reduction, as well as alternative oxidation reactions), where product selectivity imposes additional criteria on electrochemical driving force and photoelectrode architecture. By contextualizing recent literature within a fundamental framework, we seek to provide direction for continued progress toward achieving efficient and stable fuel-forming photoelectrodes.

08 HYDROGEN↗
NASA NTRS1991

LEO effects on conventional and unconventional solar cell cover materials

In 1984, the LDEF (Long Duration Exposure Facility) was placed in LEO (low earth orbit) for a mission planned to last approximately one year. The effects of the LDEF mission environment (micrometeorite/debris impacts, atomic, atomic oxygen, UV, and particulate radiation) on the samples are described. The relative importance of these interactions is highly dependent on orbital altitude. There is no evidence that the impacts with the test samples (including solar cells) caused any electrical degradation. Evidence from a number of LDEF experiments suggests that the majority of the impacts observed on this experiment were of space debris, rather than micrometeorite origin.

Stella, Paul M.↗
DOE OSTI2020

A Beehive Inspired Hydrogen Photocatalytic Device Integrating a Carbo–Benzene Triptych Material for Efficient Solar Photo–Reduction of Seawater

The dream to produce green, clean and sustainable hydrogen from earth-abundant and free resources such as seawater and sunlight is highly motivating because of the interest for desirable economical and societal applications in energy. However, it remains challenging to develop an efficient and unassisted photocatalytic device to split seawater molecules with just sunlight without any external bias. For the first time, a such novel hierarchical material has been developed, based on thin film technology that integrates TiO 2 semiconductor layers, embedded gold nanoparticles and a photosensitive carbo-benzene layer. The design of the triptych device placing the photocatalyst in be-to-be increases the photoactive surface area by a factor 2. Its stability (>120 successive hours of hydrogen production and >5 days in a day/night representative alternation) and efficiency (STH 0.06%) are measured in NaCl-salted water. Here, the chloride ions act as hole scavengers and induce an increase of pH increasing in turn the sun-driven hydrogen production rate.

42 ENGINEERING↗
NASA NTRS2006

MISSE Materials Results for Applications in the Vision for Space Exploration

Marshall Space Flight Center has a role in the development of the Crew Launch Vehicle and Crew Exploration Vehicle, as well as the Robotic Lunar Exploration Program (RLEP-2) and In-Space Propulsion. The success of these programs depends upon understanding the space environment, the requirements imposed on the spacecraft materials, and data gleaned from materials returned from space. Station Experiment (MISSE) were analyzed at the Marshall Space Flight Center. Changes in mass, optical properties, and mechanical integrity for these samples can indicate which materials may be suitable for use on exploration spacecraft, which materials need further testing, and which materials should not be recommended for long term missions. A number of materials for in-space propulsion were flown on MISSE. These include the conductive, insulative, and non-conductive tether materials selected for the ProSEDS mission. Also included were candidate solar sail materials. The solar sail materials were flown underneath a magnesium fluoride window that allowed ultraviolet radiation through to the sample but blocked any atomic oxygen. Over two hundred materials samples from the Materials on International Space

Source record↗
NASA NTRS1989

A new structure for comparing surface passivation materials of GaAs solar cells

The surface recombination velocity (S sub rec) for bare GaAs is typically as high as 10 to the 6th power to 10 to the 7th power cm/sec, which dramatically lowers the efficiency of GaAs solar cells. Early attempts to circumvent this problem by making an ultra thin junction (xj less than .1 micron) proved unsuccessful when compared to lowering S sub rec by surface passivation. Present day GaAs solar cells use an GaAlAs window layer to passivate the top surface. The advantages of GaAlAs in surface passivation are its high bandgap energy and lattice matching to GaAs. Although GaAlAs is successful in reducing the surface recombination velocity, it has other inherent problems of chemical instability (Al readily oxidizes) and ohmic contact formation. The search for new, more stable window layer materials requires a means to compare their surface passivation ability. Therefore, a device structure is needed to easily test the performance of different passivating candidates. Such a test device is described.

Desalvo, Gregory C.↗
NASA NTRS1976

Silicon materials task of the low cost solar array project, part 2

Purity requirements for solar cell grade silicon material was developed and defined by evaluating the effects of specific impurities and impurity levels on the performance of silicon solar cells. Also, data was generated forming the basis for cost-tradeoff analyses of silicon solar cell material. Growth, evaluation, solar cell fabrication and testing was completed for the baseline boron-doped Czochralski material. Measurements indicate Cn and Mn seriously degrade cell performance, while neither Ni nor Cu produce any serious reduction in cell efficiency.

Hopkins, R. H.↗
NASA NTRS1985

Results of examination of materials from the solar maximum recovery mission

Four years and two months in space at 310 nautical miles orbit has produced different effects on Kapton, silver/Teflon, and on aluminum. Kapton, a polyimide, lost up to 31% in thickness, though other locations showed much less loss. The degradation of silver/Teflon was drastic but very localized, due perhaps to the formation of silver oxide, Ag2O, through cracks in the protective Inconel layer which exposed the silver to the oxygen atom environment. Penetrations of the thin aluminum sheet in the form of thermal louvers and also of the thermal blanket material due to unknown particles were unexpected, making the debris a potentially serious problem because of the threat of damage to components.

Park, J. J.↗
NASA NTRS1979

Silicon material task - Low cost solar array project /JPL/DOE/

The paper describes the silicon material task of the low-cost solar array project, which has the objective of establishing a silicon production capability equivalent to 500 mW per year at a price less than 10 dollars/kg (1975 dollars) in 1986. The task program is divided into four phases: technical feasibility, scale-up studies (the present phase), experimental process system development units, and implementation of large-scale production plants, and it involves the development of processes for two groups of materials, that is, semiconductor grade and solar cell grade. In addition, the effects of impurities on solar cell performance are being investigated. Attention is given to problem areas of the task program, such as environmental protection, material compatibility between the reacting chemicals and materials of construction of the equipment, and waste disposal.

Lutwack, R.↗
DOE OSTI2021

Metal nitride materials for solar-thermal ammonia production [Slides]

Solar Thermal Ammonia Production has the potential to synthesize ammonia in a green, renewable process that can greatly reduce the carbon footprint left by the conventional Haber-Bosch reaction. Co 3 Mo 3 N has been identified as a potential candidate for ammonia production. It is synthesized via oxide precursor synthesis followed by nitridation under 10% H 2 /N 2 . The synthesis method can be extended to other candidate nitrides. The Co 3 Mo 3 N → Co 6 Mo 6 N reduction is demonstrated on TGA with rapid kinetics. The formation of NH 3 is qualitatively observed, but not quantitatively determined. The material retains crystal structure, but no secondary phases are observed in XRD. Partial re-nitridation back to CMN331 of ~35% of max nitridation is observed. Reaction parameters in TGA differ from experimental conditions in the literature. Experiments at Georgia Tech better mimic re-nitridation conditions with more sensitive, quantitative analytical techniques (GC-MS). The ASU NH 3 synthesis/re-nitridation reactor is under development and will permit experiments (reduction/re-nitridation) under precisely controlled T, pH 2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1972

Ultraviolet and charged particle irradiation of proposed solar cell coverslide materials and conductive coatings for the Helios spacecraft

Coverslide materials consisting of Corning 7940 fused silica, multilayers of titanium and manganese oxides (blue reflector), and indium oxide (conductive-coating) were exposed to 16 UVSC up to 800 EUVSH in vacuum. Slight changes in optical transmittance and optical absorptance were found in the (200-360) millimicron regions of the fused silica and conductive coating respectively. Exposure to 4 KeV protons and 4.5 KeV electrons in vacuum, produced decreases of several percent in transmittance, (200-360) millimicron region in the fused silicas after total fluxes less or = 10 to the 14th power particles/sq cm. Sheet resistance of the conductive coating increased above 1.0 kilo-ohm/square after a total flux less or = 10 to the 14th power particles/sq cm. Solar cells with coverglasses utilizing the indium oxide conductive coating were exposed to 1 Mev electrons and 1 Mev protons in air and in vacuum. Total fluxes ranged from 10 to the 11th power particles/sq cm to 10 to the 15th power particle/sq cm. There was no appreciable degradation in the resistance of the conductive coating during or after these tests.

Fry, J.↗
NASA NTRS1991

Requirements of a solar diffuser and measurements of some candidate materials

If the solar spectral irradiance and the orientation and directional reflectance of a solar diffuser are known, then the spectral radiance of the diffuser is readily calculated and it can be used for the accurate absolute calibration of a satellite sensor. However, the solar diffuser is exposed during in-flight satellite sensor calibration to high-energy ultraviolet irradiance, particle impacts and atomic oxygen effects. This paper describes desirable solar diffuser characteristics and the results of proton and UV irradiation on the directional-hemispheric spectral reflectance, the bidirectional spectral reflectance factor and the polarization properties of candidate diffuser materials.

Guzman, Carmen T.↗
NASA NTRS1980

Study of the effects of impurities on the properties of silicon materials and performance of silicon solar cell

Zinc is a major residue impurity in the preparation of solar grade silicon material by the zinc vapor reduction of silicon tetrachloride. It was found that in order to get a 17 percent AMl cell efficiency, the concentration of the zinc recombination centers in the base region of silicon solar cells must be less than 4 x 10 to the 11th power Zn/cu cm in the p-base n+/p/p+ cell and 7 x 10 to the 11th power Zn/cu cm in the n-base p+/n/n+ cell for a base dopant impurity concentration of 5 x 10 to the 14th power atoms/cu cm. If the base dopant impurity concentration is increased by a factor of 10 to 5 x 10 to the 15th power atoms/cu cm, then the maximum allowable zinc concentration is increased by a factor of about two for a 17 percent AMl efficiency. The thermal equilibrium electron and hole recombination and generation rates at the double acceptor zinc cancers were obtained from previous high field measurements as well as new measurements at zero field. The rates were used in the exact d.c. circuit model to compute the projections.

Sah, C. T.↗
NASA NTRS1985

Effects of coronal disturbances on the ionization state of the solar wind

A theoretical investigation of the relationship between physical conditions in coronal disturbances and the ionization states of the resulting perturbed solar wind was conducted. Available measurements of active solar wind associated with solar flares often show an enhanced degree of ionization (e.g., Fe(+17)), implying that the measured solar wind material is flare-heated at its coronal source. In contrast, other active solar wind flows sometimes show anomalously low degrees of ionization (e.g., He(+)), implying that some solar material is expelled from the corona without ever reaching coronal temperatures. The effects of impulsive heat and/or momentum addition in the corona on the hydrodynamics and ionization state of the corona and solar wind were studied. One of the primary objectives of the current grant was the development of a software package suitable for: (1) generating models for the effects of impulsive heat and/or momentum deposition on plasma temperatures, densities and flow velocities; and (2) calculating the ionization state of the solar wind as a function of the location, duration and magnitude of heat and/or momentum deposition.

Withbroe, G. L.↗
DOE OSTI2023

The Materials Provenance Store

Abstract We present a database resulting from high throughput experimentation, primarily on metal oxide solid state materials. The central relational database, the Materials Provenance Store (MPS), manages the metadata and experimental provenance from acquisition of raw materials, through synthesis, to a broad range of materials characterization techniques. Given the primary research goal of materials discovery of solar fuels materials, many of the characterization experiments involve electrochemistry, along with optical, structural, and compositional characterizations. The MPS is populated with all information required for executing common data queries, which typically do not involve direct query of raw data. The result is a database file that can be distributed to users so that they can independently execute queries and subsequently download the data of interest. We propose this strategy as an approach to manage the highly heterogeneous and distributed data that arises from materials science experiments, as demonstrated by the management of over 30 million experiments run on over 12 million samples in the present MPS release.

36 MATERIALS SCIENCE↗