Search NASA⌕ Search

SEARCH · Search NASA

Results for “metal toxicity”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

The promise of metal-halide-perovskite solar photovoltaics: A brief review

Solar photovoltaics (PVs) based on metal-halide perovskites (MHPs) have taken the renewable-energy world by storm. The excitement stems from the promise of a high-efficiency, low-cost, and low “carbon-footprint” new PV technology. Here, a brief overview of the important topics pertaining to MHPs, perovskite solar cells (PSCs) and perovskite solar modules (PSMs) is presented. The topics include: (1) PSC architectures, (2) MHPs, (3) synthesis and processing of MHP thin films, (4) MHP thin-film microstructures, (5) PSC functional layers, (6) interfacial engineering in PSCs, (7) PSC performance, (8) PSC stability, (9) PSMs, (10) lead toxicity, and (11) mechanical behavior and reliability. The significant challenges in the path toward commercialization of this burgeoning PV technology are also highlighted. Chief among them are scalability, stability, reliability, and safety, while achieving high efficiency, low cost, and low “carbon-footprint.” Furthermore, the promise of this new PV technology and the fascinating underlying science make it a worthwhile endeavor to address these challenges.

14 SOLAR ENERGY↗
DOE OSTI2023

Low-temperature liquid-phase formation of environmentally stable copper halide nanocrystal superlattices and their application to anticounterfeiting patterns

Nanocrystal superlattices have the potential to create a new class of semiconductor materials by combining the photophysical properties of individual nanocrystals with bulk-like structure performance. However, the principles underlying the direct formation of superlattices in liquid phase have not been thoroughly investigated, particularly, those consisting of exciton self-trapping metal halides. Here, in this work, we explore the formation of Cs 3 Cu 2 Br 5 nanocrystal superlattices via liquid-phase crystallization of growing nanocrystals over a reaction period of only a few seconds. Importantly, the reaction temperature and the precursor concentration were found to be key parameters governing the concomitant nanocrystal growth and superlattice formation. The resulting Cs 3 Cu 2 Br 5 superlattices had a well-defined face-centered cubic structure and emitted a single-band bright blue emission when exposed to 280 nm light. Owing to their advantages, such as low toxicity, reabsorption-free, narrow absorption, strong emission, and high environmental stability, the Cs 3 Cu 2 Br 5 superlattices were applicable to anti-counterfeiting applications. Our findings shed light on the liquid-phase assembly of nanocrystals into superlattices and highlight the potential applications of the superlattices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Conversion of Compositionally Diverse Plastic Waste over Earth-Abundant Sulfides

Chemical deconstruction of polyolefin plastic wastes via hydroconversion is promising for mitigating plastic accumulation in landfills and the environment. However, hydroconversion catalysts cannot handle complex feedstocks containing multiple polymers, additives, and heteroatom impurities. Here, we report a single-step strategy using earth-abundant metal sulfide catalysts to deconstruct these wastes. We show that NiMoS x /HY catalysts deconstruct polyolefin feedstocks, achieving ~81–94% selectivity to liquid products. Postsynthetic zeolite modification enhances the catalyst’s activity by >2.5 times, achieving over 95% selectivity to liquid fuels with controllable product distribution in the naphtha, jet fuel, and diesel range. The catalyst is resilient to increasingly complex feedstocks, such as additive-containing polymers and mixed plastics composed of polyolefins and heteroatom-containing polymers, including poly(vinyl chloride). As a result, we extend the strategy to single-use polyolefin wastes that can generate toxic byproducts, such as HCl and NH 3 , and eliminate their emissions by integrating reaction and sorption in a one-step process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Multi-Analytical Investigation of Arsenical Transfer and Remediation on Nineteenth-Century Green Books

Books containing heavy metals, specifically nineteenth-century green arsenical books, have been identified at Northwestern University Libraries, raising health and safety concerns related to handling. Copper acetoarsenite pigments, such as emerald green, were detected on book covers, decorative page edges, labels, and other components using noninvasive analytical techniques including X-ray fluorescence (XRF), Raman spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. Further examination of selected volumes using synchrotron radiation (SR) techniques revealed pigment migration, degradation, and arsenic transfer to adjacent books. This paper expands on initial findings through two related experiments. The first explored the transfer of arsenic using mechanical friction; Staedtler Mars® white vinyl erasers rubbed on arsenical books generated crumbs which were analyzed via scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX). Results confirmed the transfer of arsenic, copper, and lead, with decorative page edges being particularly prone to shedding arsenic onto other materials. The second experiment tested remediation methods on a book contaminated by prolonged exposure to an arsenical neighbor. Surface cleaning using erasers and a vacuum removed flecks of pigment but did not eliminate non-chromophoric arsenic as confirmed by SR analyses, which highlights its presence either as a degradation product embedded within the paper or present in the paper as part of its production process. Findings demonstrate the acute toxicity risk posed by arsenical books and support the need for safe handling protocols. However, materials with only trace levels of arsenic embedded during production may pose a lower risk of transfer. Cross contamination beyond prolonged direct contact appears limited. These results highlight critical considerations for library preservation practices and future research on arsenic in historical materials.

arsenic↗
DOE OSTI2020

On-device lead sequestration for perovskite solar cells

Perovskite solar cells, as an emerging high-efficiency and low-cost photovoltaic technology face challenges on their way towards commercialization. Substantial improvements have been made to device stability but potential issues with lead toxicity and leaching from devices remain relatively unexplored. The potential for lead leakage could be perceived as an environmental and public health risk when using perovskite solar cells in building-integrated photovoltaics. Here we present a chemical approach for on-device sequestration of more than 96 per cent of lead leakage caused by severe device damage. A coating of lead-absorbing material is applied to the front and back sides of the device stack. On the glass side of the front transparent conducting electrode, we use a transparent lead-absorbing molecular film containing phosphonic acid groups that bind strongly to lead. On the back (metal) electrode side, we place a polymer film blended with lead-chelating agents between the metal electrode and a standard photovoltaic packing film. The lead-absorbing films on both sides swell to absorb the lead, rather than dissolve, when subjected to water soaking, thus retaining structural integrity for easy collection of lead after damage.

14 SOLAR ENERGY↗
DOE OSTI2024

A Green, Fire–Retarding Ether Solvent for Sustainable High–Voltage Li–Ion Batteries at Standard Salt Concentration

Lithium-ion batteries (LIBs) are increasingly encouraged to enhance their environmental friendliness and safety while maintaining optimal energy density and cost-effectiveness. Although various electrolytes using greener and safer glyme solvents have been reported, the low charge voltage (usually lower than 4.0 V vs Li/Li + ) restricts the energy density of LIBs. Herein, tetraglyme, a less-toxic, non-volatile, and non-flammable ether solvent, is exploited to build safer and greener LIBs. It is demonstrated that ether electrolytes, at a standard salt concentration (1 m), can be reversibly cycled to 4.5 V vs Li/Li + . Anchored with Boron-rich cathode-electrolyte interphase (CEI) and mitigated current collector corrosion, the LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode delivers competitive cyclability versus commercial carbonate electrolytes when charged to 4.5 V. Synchrotron spectroscopic and imaging analyses show that the tetraglyme electrolyte can sufficiently suppress the overcharge behavior associated with the high-voltage electrolyte decomposition, which is advantageous over previously reported glyme electrolytes. The new electrolyte also enables minimal transition metal dissolution and deposition. NMC811||hard carbon full cell delivers excellent cycling stability at C/3 with a high average Coulombic efficiency of 99.77%. In conclusion, this work reports an oxidation-resilient tetraglyme electrolyte with record-high 4.5 V stability and enlightens further applications of glyme solvents for sustainable LIBs by designing Boron-rich interphases.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Oxygen extraction from lunar soil by fluorination

Mining and processing of lunar material could possibly lead to more cost-efficient scenarios for permanent presence of man in space and on the Moon. Production of oxygen for use as propellant seems especially important. Different candidate processes for oxygen-extraction from lunar soil were proposed, of which the reduction of ilmenite by hydrogen was studied most. This process, however, needs the concentration of ilmenite from lunar regolith to a large extent and releases oxygen only with low efficiency. Another possibility - the fluorination method - which works with lunar bulk material as feedstock is discussed. Liberation of oxygen from silicate or oxide materials by fluorination methods has been applied in geoscience since the early sixties. The fact that even at moderate temperatures 98 to 100 percent yields can be attained, suggests that fluorination of lunar regolith could be an effective way of propellant production. Lunar soil contains about 50 percent oxygen by weight which is gained nearly completely through this process as O2 gas. The second-most element Si is liberated as gaseous SiF4. It could be used for production of Si-metal and fluorine-recycling. All other main elements of lunar soil will be converted into solid fluorides which also can be used for metal-production and fluorine-recycling. Preliminary results of small scale experiments with different materials are discussed, giving information on specific oxygen-yields and amounts of by-products as functions of temperature. These experiments were performed with an already existing fluorine extraction and collection device at the University of Bonn, normally used for determination of oxygen-isotopic abundances. Optimum conditions, especially concerning energy consumption, are investigated. Extrapolation of the experimental results to large industrial-type plants on the Moon is tried and seems to be promising at first sight. The recycling of the fluorine is, however, crucial for the process. It might be achieved by means of electrolysis. This needs further investigation. The technical problem of transport and handling of the toxic and corrosive fluorine seems to be solvable and could be done by inert storage vessels.

Seboldt, W.↗
DOE OSTI2025

Fabrication of nanoporous doped metal oxide coatings via selective infiltration of a block copolymer template: The case of Al-doped zinc oxide

Conductive nanoporous conformal coatings are important for various applications including touchscreens, displays, and electrochromic windows, though design of such coating with controlled porosity and composition remains challenging. We propose a sequential infiltration synthesis (SIS) method for the fabrication of nanoporous conductive aluminum-doped zinc oxide (AZO) films by infiltrating block copolymer (BCP) templates, specifically polystyrene-block-polyvinyl pyridine (PS-b-P4VP), with diethyl zinc and trimethyl aluminum precursors. Tunability of both porosity and electrical conductivity is achieved by precisely controlling the swelling behavior of the polymer templates and adjusting the number of SIS cycles. Further, our results reveal that porosity levels can reach up to 80 %, with resistivity as low as ~7.83 Ωcm. Using conductive atomic force microscopy (C-AFM) and Hall effect measurements, we show that lower concentrations of aluminum doping relative to zinc (around 1: 17) results in higher conductivity of the AZO films. Additionally, AZO is based on zinc oxide (ZnO) which is cost-efficient, abundant and less toxic than commonly used transparent conductive oxides such as indium tin oxide (ITO) and fluorine-doped tin oxide (FTO). Therefore, this novel approach opens new possibilities for creating highly porous, conformal, conductive AZO coatings with customizable porosity and composition, making them ideal candidates for diverse optoelectronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Removal, distribution and retention of metals in a constructed wetland over 20 years

The A-01 wetland treatment system (WTS) was designed to remove metals (primarily copper) from the effluent at the A-01 National Pollution Discharge Elimination System (NPDES) outfall at the Savannah River Site, Aiken, SC. This research investigated metal removal, distribution and retention in the A-01 WTS over a period of 20 years. The findings are important for ensuring continued metal sequestration in the A-01 WTSs over time, providing management guidance for constructed wetlands, and investigating changes in metal remediation effectiveness as a wetland ages. During 20 years of operation, systematic water and sediment sampling validated the wetlands' performance. After passage through the treatment cells, Cu concentrations were well below permit limits during all years of operation, often falling below 10 μg L -1 . Cu removal has been consistent over time, averaging about 80% despite large changes in influent Cu concentrations. Most divalent metals were rapidly removed from the water and held in the sediments shortly after the water entered the treatment wetland. Average removal of Pb from water by the wetland system was 67 and 74% in 2004 and 2020, respectively. Comparable values for Zn were 52 and 65%, respectively. Generally, the highest concentrations of Cu, Pb, and Zn were found in the sediment from the first cell in each pair of cells suggesting that most of the Cu, Pb, and Zn in the A-01 effluent was bound to the sediment quickly. Diffusive gradients in thin films (DGT) measurements of Cu and Zn in the sediments were much lower than bulk sediment concentrations. These results suggest that most of the Cu and Zn in the A-01 WTS sediments was not bioavailable, hence not toxic to aquatic organisms, as a likely consequence of adsorption to sediment particles and complexation with organic and inorganic substances.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

2020 Results for Avian Monitoring of Inorganic and Organic Element Concentrations in Passerine Eggs and Nestlings Collected from Technical Area 16 Burn Grounds, Technical Area 36 Minie, and Technical Area 39 Point 6 at Los Alamos National Laboratory

In 2020, non-viable avian eggs and two nestling were opportunistically collected at Los Alamos National Laboratory (LANL) near open detonation sites located at Technical Area (TA) 16 burn grounds, TA-36 Minie, and TA-39 Point 6. These samples were evaluated for inorganic elements (mostly metals), dioxins, and furans. A total of six eggs and two deceased western bluebird (Sialia mexicana) nestling samples were collected among the three locations of interest. Concentrations of inorganic elements observed in this study were compared with the regional statistical reference level (RSRL) which is the upper-level bounds of background concentrations (mean + three standard deviations = 99% confidence interval). Several inorganic elements were not detected in avian eggs and all inorganic elements detected were below the RSRL and the lowest observable adverse effect level (LOAEL), when available. One nestling collected from TA-39 contained detectable concentrations of two dioxin congeners. Heptachlorodibenzodioxin-1,2,3,4,6,7,8 and octachlorodibenzodioxin-1,2,3,4,6,7,8,9 concentration exceeded the RSRL, but did not exceed the calculated tetrachlorodibenzodioxin 2,3,7,8 (TCDD) toxic equivalent LOAEL. These data suggest that inorganic and organic element concentrations in eggs and nestlings are not of ecological concern. More data are needed to make a robust assessment and to evaluate trends over time.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Leaving in the lead: Priorities for perovskite photovoltaics

The need for moving electricity generation to a sustainable model requires the development of low cost ubiquitous photovoltaics (PVs) to harvest the planet’s primary energy source, the Sun. Building upon the successes of Si-based and CdTe-based PV technologies, PVs with lower-embodied energy and requiring lower carbon dioxide equivalent to produce will be required to meet long-term sustainability goals. In particular, thin-film technologies, such as high-efficiency metal halide perovskite (MHP) PV modules, provide avenues to reduced embodied energy, lower energy payback times, and enabling energy-dense tandems [H. M. Wikoff et al., Joule 6(7), 1710–1725 (2022) and V. Fthenakis, Renewable Sustainable Energy Rev. 13(9), 2746–2750 (2009)]. The ability to improve efficiency and lower energy payback time of next generation thin-film PV modules is a critical foundation for green H2 and electrification more broadly. In this regard, Pb-based MHP-PVs have separated themselves as a result of the high-efficiencies that can be realized across a range of electronic gaps. Questions regarding Pb-based MHP-PVs that are often asked, as the challenges of efficiency and reliability are met, revolve around the “problem” of the Pb content. Specifically, “does Pb toxicity preclude MHP-PV modules from being deployed at the TW scale?” To provide this sense of scale, in 2021, the United States burned 10.5 quads of coal, with 90% of that used for electricity generation. Given the energy content of coal of 29 MJ/kg and a residual lead content in that coal of 30 mg/kg, electricity generation from coal resulted in more lead emitted into the atmosphere than what would be required to produce over 2 TW of MHP-PV name plate capacity (assuming a 20% module efficiency and an ∼700 nm active layer). This amounts to more PV power than has been deployed across all PV technologies and geographies to date. This only includes US coal consumption; the rest of the world would be much larger. This example illustrates the scale of the material usage relative to the energy production. Imagine a power-generation technology that offsets these Pb emissions from coal and essentially sequesters this Pb content between two sheets of impermeable glass. Why should we let Pb’s history of misuse prevent it from being included in next generation PV modules that can enable a sustainable energy future?

14 SOLAR ENERGY↗
NASA NTRS1993

Characterization of Minnesota lunar simulant for plant growth

Processing of lunar regolith into a plant growth medium is crucial in the development of a regenerative life support system for a lunar base. Plants, which are the core of such a system, produce food and oxygen for humans and, at the same time, consume carbon dioxide. Because of the scarcity of lunar regolith, simulants must be used to infer its properties and to develop procedures for weathering and chemical analyses. The Minnesota Lunar Simulant (MLS) has been identified to date as the best available simulant for lunar regolith. Results of the dissolution studies reveal that appropriately fertilized MLS can be a suitable medium for plant growth. The techniques used in conducting these studies can be extended to investigate the suitability of actual lunar regolith as a plant growth medium. Dissolution experiments were conducted using the MLS to determine its nutritional and toxicity characteristics for plant growth and to develop weathering and chemical analysis techniques. Two weathering regimes, one with water and one with dilute organic acids simulating the root rhizosphere microenvironment, were investigated. Elemental concentrations were measured using inductively-coupled-plasma (ICP) emission spectrometry and ion chromatography (IC). The geochemical speciation model, MINTEQA2, was used to determine the major solution species and the minerals controlling them. Acidification was found to be a useful method for increasing cation concentrations to meaningful levels. Initial results indicate that MLS weathers to give neutral to slightly basic solutions which contain acceptable amounts of the essential elements required for plant nutrition (i.e., potassium, calcium, magnesium, sulfur, zinc, sodium, silicon, manganese, copper, chlorine, boron, molybdenum, and cobalt). Elements that need to be supplemented include carbon, nitrogen, and perhaps phosphorus and iron. Trace metals in solution were present at nontoxic levels.

Oglesby, James P.↗
NASA NTRS2017

Pulmonary Inflammatory Responses to Acute Meteorite Dust Exposures - to Acute Meteorite Dust Exposures - Exploration

New initiatives to begin lunar and martian colonization within the next few decades are illustrative of the resurgence of interest in space travel. One of NASA's major concerns with extended human space exploration is the inadvertent and repeated exposure to unknown dust. This highly interdisciplinary study evaluates both the geochemical reactivity (e.g. iron solubility and acellular reactive oxygen species (ROS) generation) and the relative toxicity (e.g. in vitro and in vivo pulmonary inflammation) of six meteorite samples representing either basalt or regolith breccia on the surface of the Moon, Mars, and Asteroid 4Vesta. Terrestrial mid-ocean ridge basalt (MORB) is also used for comparison. The MORB demonstrated higher geochemical reactivity than most of the meteorite samples but caused the lowest acute pulmonary inflammation (API). Notably, the two martian meteorites generated some of the highest API but only the basaltic sample is significantly reactive geochemically. Furthermore, while there is a correlation between a meteorite's soluble iron content and its ability to generate acellular ROS, there is no direct correlation between a particle's ability to generate ROS acellularly and its ability to generate API. However, assorted in vivo API markers did demonstrate strong positive correlations with increasing bulk Fenton metal content. In summary, this comprehensive dataset allows for not only the toxicological evaluation of astromaterials but also clarifies important correlations between geochemistry and health.

Harrington, A. D.↗
NASA NTRS1977

Characterization of secondary ignition sources in unattended compartments and full-scale baseline test

The characteristics of five fuel loads burned within a metal lavatory were identified. In 15 of the tests the lavatory door remained closed for the 30-minute test period while in 15 additional tests the door was opened after the fire had developed. Upon completion of these tests the most severe source was selected for use in the baseline test. In the baseline test, the lavatory and adjacent panels, all of which were constructed of contemporary materials, were tested for a period of 1 hour. Thermal, environmental, and biological data were obtained for all fuel loads, door conditions, and the baseline test. All tests were conducted in a cabin fire simulator with separate ventilation of the cabin and lavatory representative of an inflight condition. The baseline test established that by using the most severe fuel source: (1) the exposed animal subject survived without complications; (2) no toxic levels of gas within the cabin were detected; (3) a propagating fire did not develop in adjacent structures; (4) the lavatory containing the fire remained structurally intact; (5) decomposition of portions of the lavatory did occur; and (6) cabin visibility would have presented a problem after 5 minutes.

Klink, D. M.↗
DOE OSTI2025

Cetyltrimethylammonium Bromide/Chloride on Gold Nanocrystals Can Be Directly Replaced with Tri-Citrate

This work demonstrates an effective method for directly exchanging the toxic cetyltrimethylammonium bromide/chloride (CTAB/C) on Au nanocrystals with tri-citrate. Our experimental and computational studies indicate that counterion plays a vital role in the exchange process. Specifically, when citrate species bind to Au surface, they all evolve into tri-citrate with different counterions. In the case of three H + counterions, tri-citrate could readily replace the CTAB/C due to a strong binding of the carboxylate group with the Au surface. The substitution of H + counterion by Na + or K + weakens the binding strength and thus compromises the exchange. Additionally, our quantitative measurements and theoretical calculations indicate that Au nanospheres encased by high-index facets are advantageous over their counterparts enclosed by {111} and/or {100} facets for the exchange owing to the difference in binding strength. The mechanistic insights and experimental control should be extendable to other combinations of surface ligands and metal nanocrystals.

adsorption↗
DOE OSTI2020

2019 Results for Avian Monitoring of Inorganic and Organic Element Concentrations in Passerine Eggs and a Nestling Collected from Technical Area 16 Burn Grounds, Technical Area 36 Minie, and Technical Area 39 Point 6 at Los Alamos National Laboratory

In 2019, non-viable avian eggs and one nestling were opportunistically collected at Los Alamos National Laboratory (LANL) near open detonation sites located at Technical Area (TA) 16 burn grounds, TA-36 Minie, and TA-39 Point 6. These samples were evaluated for inorganic elements (mostly metals), polychlorinated biphenyls (PCBs), dioxins, and furans. A total of 26 western bluebird (Sialia mexicana) and five mountain bluebird (Sialia currucoides) egg samples and one non-viable ash-throated flycatcher (Myiarchus cinerascens) nestling were collected among the three locations of interest. Concentrations of inorganic elements observed in this study were compared with the regional statistical reference level (RSRL) which is the upper-level bounds of background concentrations (mean + three standard deviations = 99% confidence interval). Several inorganic elements were not detected in avian eggs and the majority of inorganic elements detected were below the RSRL. The few elements that exceeded the RSRL were below the lowest observable adverse effect level (LOAEL), when available. One nestling collected from TA-16 contained detectable concentrations of some dioxin and furan congeners. Octachlorodibenzodioxin-1,2,3,4,6,7,8,9 concentration exceeded the RSRL, but did not exceed the calculated tetrachlorodibenzodioxin-2,3,7,8 (TCDD) toxic equivalent LOAEL. PCBs were also detected in the nestling sample and were above the RSRL but below the LOAEL. These data suggest that inorganic and organic element concentrations in eggs and nestlings are not of ecological concern. More data are needed to make a robust assessment and to evaluate trends over time.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Reaction–Diffusion Coupling Facilitates the Sequential Precipitation of Metal Ions from Battery Feedstock Solutions

Here, the development of new technologies for chemical separations is urgently needed to meet the surging demand for critical materials that has strained resources and caused environmental challenges. Inspired by the classic Liesegang experiment, we demonstrated the separation of critical metal ions based on the coupling of ion diffusion and precipitation kinetics. For this purpose, a model feedstock solution simulating dissolved battery electrodes was placed on top of a hydrogel loaded with a precipitating agent, namely sodium hydroxide. As the lithium, manganese, cobalt, and nickel ions diffused into the gel, a gradient of precipitates formed along the length of the reactor. Elemental analysis of the spatially distributed precipitates showed the enrichment of nickel near the gel-solution interface, followed by the formation of an almost pure (>96%) manganese product further along the reactor. Optimization experiments revealed that a sodium hydroxide concentration of 10 mM and a gel/solution volume ratio of 2:1 favored efficient separations. The robustness of the method was demonstrated in four out of five feedstock compositions of typically used battery cathodes. Our proof-of-concept experiments present a paradigm for critical materials separations that does not require specialty chemicals, binding agents, membranes, or toxic solvents.

25 ENERGY STORAGE↗
NASA NTRS2004

Transient Torque Method: A Fast and Nonintrusive Technique to Simultaneously Determine Viscosity and Electrical Conductivity of Semiconducting and Metallic Melts

A transient torque method was developed to rapidly and simultaneously determine the viscosity and electrical conductivity of liquid metals and molten semiconductors. The experimental setup of the transient torque method is similar to that of the oscillation cup method. The melt sample is sealed inside a fused silica ampoule, and the ampoule is suspended by a long quartz fiber to form a torsional oscillation system. A rotating magnetic field is used to induce a rotating flow in the conductive melt, which causes the ampoule to rotate around its vertical axis. A sensitive angular detector is used to measure the deflection angle of the ampoule. Based on the transient behavior of the deflection angle as the rotating magnetic field is applied, the electrical conductivity and viscosity of the melt can be obtained simultaneously by numerically fitting the data to a set of governing equations. The transient torque viscometer was applied successfully to measure the viscosity and electrical conductivity of high purity mercury at 53.4 C. The results were in excellent agreement with published data. The method is nonintrusive; capable of rapid measurement of the viscosity of toxic, high vapor pressure melts at elevated temperatures. In addition, the transient torque viscometer can also be operated as an oscillation cup viscometer to measure just the viscosity of the melt or as a rotating magnetic field method to determine the electrical conductivity of a melt or a solid if desired.

Li, C.↗