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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Effect of CO 2 Concentration on the Microbial Activity of Orenia metallireducens (Strain Z6) in Surface Inert Materials

Carbon dioxide (CO 2 ) sequestration has garnered widespread attention as a key strategy for mitigating CO 2 emissions and combating the greenhouse effect. However, the mechanisms underlying the interactions between CO 2 , widespread siliceous minerals and biological processes remain unclear. The present study explored the potential impacts of different CO 2 concentrations on microbial activity, environmental conditions and their feedback on the fate of CO 2 . A total of 20 experimental conditions was created, with the variables including different natural and synthetic siliceous minerals (e.g., quartz sand and a type of commercial glass beads), the presence or absence of the iron-reducing microorganism Orenia metallireducens (strain Z6) and varying CO 2 concentrations (0%, 20%, 50%, 100%) in the presence of ferrihydrite and pyruvate. Geochemical, microbial and mineralogical analyses revealed that elevated CO 2 concentrations significantly inhibited microbial Fe(III) reduction and pyruvate metabolism. Interestingly, compared to cultures without mineral amendments or those with glass beads alone, the addition of quartz sand enabled strain Z6 to better withstand the environmental stress caused by elevated CO 2 , promoting pyruvate fermentation and iron reduction. In addition to an increased pH, the formation of siderite, hematite and vivianite was also observed in the bioactive systems. Although both glass beads and quartz sand were primarily composed of silica, differences in the mineral structure, elemental composition and acid neutralization capacity rendered quartz sand more chemically active and unexpectedly led to greater CO 2 sequestration.

CO2 stress↗
DOE OSTI2022

Water Formation Reaction under Interfacial Confinement: Al0.25Si0.75O2 on O-Ru(0001)

Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of Al0.25Si0.75O2. We investigated the kinetics of WFR at elevated H2 pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H2 was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*H2O + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Dependence of Dust Formation on the Supernova Explosion

We investigate the properties, composition, and dynamics of dust formation and growth for a diverse set of core-collapse supernovae (CCSNe), with 15, 20, and 25 M ⊙ progenitor masses, explosion energies ranging from 0.5 to 120 foe, and varied engine type. These explosions are evolved with a 1D Lagrangian hydrodynamics code out to a minimum of 1157 days to model the ejecta as it expands and cools. A multigrain dust nucleation and growth model is applied to these results. We find that higher explosion energies lead to an earlier onset of dust formation, smaller grain sizes, and larger silicate abundances. Further, we see that nuclear burning during the explosion leads to enhanced formation of silicate dust. Finally, we build composite models from our suite to predict the efficiency of CCSN dust production as a function of metallicity.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Cold Gas and Star Formation in the Phoenix Cluster with JWST

We present integral field unit observations of the Phoenix Cluster with the JWST Mid-infrared Instrument’s Medium Resolution Spectrometer. We focus this study on the molecular gas, dust, and star formation in the brightest cluster galaxy (BCG). We use precise spectral modeling to produce maps of the silicate dust, molecular gas, and polycyclic aromatic hydrocarbons (PAHs) in the inner ∼50 kpc of the cluster. We measure the optical depth from silicates by comparing the observed H 2 line ratios to those predicted by excitation models. We provide updated measurements of the total molecular gas mass of $1.9^{+0.5}_{-0.04}$ x 10 10 M ⊙ , which agrees with CO-based estimates, providing an estimate of the CO-to-H 2 conversion factor of α CO = 0.8 ± 0.2 M ⊙ pc -2 (K km s -1 ) -1 ; an updated stellar mass of M * = 2.6 ± 0.5 × 10 10 M ⊙ ; and star formation rates (SFRs) averaged over 10 and 100 Myr of $\langle$SFR$\rangle$ 10 = 1340 ± 100 M ⊙ yr −1 and $\langle$SFR$\rangle$ 100 = 740 ± 80 M ⊙ yr −1 , respectively. The H 2 emission seems to be powered predominantly by shocks and star formation within the central ∼20 kpc, induced by stellar feedback and radio jets from the active galactic nucleus. Additionally, we find nearly an order-of-magnitude drop in the SFRs estimated by PAH fluxes in cool core BCGs compared to field galaxies, suggesting that hot particles from the intracluster medium are destroying PAH grains even in the central-most tens of kiloparsecs.

Active galaxies↗
DOE OSTI2022

Mixing of Condensable Constituents with H–He during the Formation and Evolution of Jupiter

Simulations of Jupiter's formation are presented that incorporate mixing of H–He with denser material entering the planet as solids. Heavy compounds and gas mix substantially when the planet becomes roughly as massive as Earth, because incoming planetesimals can fully vaporize. Supersaturation of vaporized silicates causes the excess to sink as droplets, but water remains at higher altitudes. Because the mean molecular weight decreases rapidly outward, some of the compositional inhomogeneities produced during formation can survive for billions of years. After 4.57 Gyr, our Jupiter model retains compositional gradients; proceeding outward, one finds (i) an inner heavy-element core, the outer part derived from hot supersaturated rain-out; (ii) a composition-gradient region, containing most of the heavy elements, where H–He abundance increases outward, reaching about 0.9 mass fraction at 0.3 of the radius, with silicates enhanced relative to water in the lower parts and depleted in the upper parts; (iii) a uniform-composition region (neglecting He immiscibility) that is enriched over protosolar and contains most of the planet’s mass; and (iv) an outer region where cloud formation (condensation) of heavy constituents occurs. This radial compositional profile has heavy elements more broadly distributed than predicted by classical formation models but less diluted than suggested by Juno-constrained gravity models. The compositional gradients in the region containing the bulk of the heavy elements prevent convection, in both our models and those fitting current gravity, resulting in a hot interior where much of the accretion energy remains trapped.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Chapmanite [Fe 2 Sb(Si 2 O 5 )O 3 (OH)]: thermodynamic properties and formation in low-temperature environments

Abstract. of synthetic Sb 2 O 5 , MgSb 2 O 6 (analogue of the mineral byströmite), Mg[Sb(OH) 6 ] 2 ∙6H 2 O (brandholzite), and natural chapmanite [(Fe 1.88 Al 0.12 )Sb(Si 2 O 5 )O 3 (OH)]. Enthalpies of reactions, including formation enthalpies, were evaluated using reference compounds Sb, Sb 2 O 3 , Sb 2 O 5 , and other phases, with high-temperature oxide melt solution calorimetry in lead borate and sodium molybdate solvents. Heat capacity and entropy were determined by relaxation and differential scanning calorimetry. The best set of Δ f H o (kJ mol -1 ) and S o (J mol -1 K -1 ) is byströmite -1733.0±3.6, 139.3±1.0; brandholzite -5243.1±3.6, 571.0±4.0; and chapmanite -3164.9±4.7, 305.1±2.1. The data for chapmanite give Δ f G o of -2973.6±4.7 kJ mol -1 and log K=-17.10 for the dissolution reaction (Fe 1.88 Al 0.12 )Sb(Si 2 O 5 )O 3 (OH) + 6H + → 1.88Fe 3+ + 0.12Al 3+ + 2SiO$_2^0$ + Sb(OH)$_3^0$ + 2H 2 O. Analysis of the data showed that chapmanite is finely balanced in terms of its stability with schafarzikite (FeSb 2 O 4 ) and tripuhyite (FeSbO 4 ) under a specific, narrow range of conditions when both aqueous Fe(III) and Sb(III) are abundant. In such a model, chapmanite is metastable by a narrow margin but could be stabilized by high SiO$_2^0$(aq) activities. Natural assemblages of chapmanite commonly contain abundant amorphous silica, suggesting that this mechanism may be indeed responsible for the formation of chapmanite. Chapmanite probably forms during low-temperature hydrothermal overprint of pre-existing Sb ores under moderately reducing conditions; the slightly elevated temperatures may help to overcome the kinetic barrier for its crystallization. During weathering, sheet silicates may adsorb Sb 3+ in tridentate hexanuclear fashion, thus exposing their chapmanite-like surfaces to the surrounding aqueous environment. Formation of chapmanite, as many other sheet silicates, under ambient conditions, is unlikely.

58 GEOSCIENCES↗
DOE OSTI2020

Cell-based composite materials with programmed structures and functions

The present invention is directed to the use of silicic acid to transform biological materials, including cellular architecture into inorganic materials to provide biocomposites (nanomaterials) with stabilized structure and function. In the present invention, there has been discovered a means to stabilize the structure and function of biological materials, including cells, biomolecules, peptides, proteins (especially including enzymes), lipids, lipid vesicles, polysaccharides, cytoskeletal filaments, tissue and organs with silicic acid such that these materials may be used as biocomposites. In many instances, these materials retain their original biological activity and may be used in harsh conditions which would otherwise destroy the integrity of the biological material. In certain instances, these biomaterials may be storage stable for long periods of time and reconstituted after storage to return the biological material back to its original form. In addition, by exposing an entire cell to form CSCs, the CSCs may function to provide a unique system to study enzymes or a cascade of enzymes which are otherwise unavailable.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

High capacity, air-stable, structurally isomorphous lithium alloy multilayer porous foams

The invention relates to composite multilayer lithium ion battery anodes that include a porous metal alloy foam, and a lithium ion conductor coating applied to the metal alloy foam. The metal alloy foam can include structurally isomorphous alloys of lithium and, optionally, lithium and magnesium. The lithium ion conductor coating can include ternary lithium silicate, such as, lithium orthosilicate. Lithium ions from the ternary lithium silicate may be deposited within the pores of the metal alloy foam. Optionally, the lithium ion conductor coating may include a dopant. The dopant can include one or more of magnesium, calcium, vanadium, niobium and fluorine, and mixtures and combinations thereof.

Kumta, Prashant N.↗
DOE OSTI2021

Piezoelectric response and failure behavior of cement paste under external loading

We study the elastic behavior and rupture mechanism of Calcium Silicate Hydrates (C-S-H) in response to tensile loading. For the three tensile axes, initial defects are spotted in the interlayer regions. However, the crack propagation is rather different depending on the axis of tensile. The cup-and-cone failure surface shows the ductile feature of C-S-H in the x and y directions; while the devastating rupture mode confirms the brittle feature of C-S-H in the z direction. Piezoelectricity was investigated using the charge fluctuation method. The polarization variation in response to small strain was also investigated and piezoelectric coefficients were derived. Furthermore, dependence of elastic and piezoelectric properties over external pressure was analyzed. Results reveal an improvement of the mechanical properties and the ultimate strength especially in the z direction; whereas the non-piezoelectricity remains unchanged despite the rearrangement of atoms induced by the external applied pressure.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Cs retention and diffusion in C-S-H at different Ca/Si ratio

Cement and concrete are commonly used in the construction of repository sites for radioactive wastes. The correct isolation of those contaminants requires good adsorption and low diffusion rates. Both parameters are highly affected by many factors, such as pH, temperature or composition. The large variability of experimental conditions and formulations makes it extraordinarily difficult to tackle the influence of each of them independently in experimental samples. To this effect, molecular dynamics simulations have been employed in this study to investigate the role of the composition in the capacity to retain Cs and diffusivity of these ions in calcium silicate hydrate (C-S-H) gel pores. The results indicate that the adsorption of Cs ions is worsened at high Ca/Si ratios due to a lower interaction of the cations with the C-S-H surface, while hydrophilicity of the C-S-H nanopore rises, resulting in higher long-range ordering and lower diffusion coefficients of Cs ions.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Mechanical and physical properties of inorganic polymer cement made of iron-rich laterite and lateritic clay: A comparative study

In this work, two different laterites (iron contents of 13.07 and 49.34 wt%, respectively, for lateritic clay, LAC, and iron-rich laterite, LAI) were selected and calcined at 600 °C. The obtained calcined laterites, namely LAI600 and LAC600, were separately mixed with an alkaline solution (silicate modulus of 1.35) or an acidic solution (phosphoric acid solution at pH ≤ 2) for the synthesis of inorganic polymer products. The fabricated products were cured at 20 °C (ambient) and 40 °C (oven). The obtained results showed that the compressive strength of each series of alkaline-based inorganic polymer binder increased with ageing time (7 and 28 days) for room temperature curing, while the reverse trend was noted for oven-cured specimens. The best mechanical performance was obtained when using a phosphoric acid solution, 38 and 52 ± 1 MPa; 62 and 65 ± 1 MPa at 28 days for LAC and LAI respectively. It appeared that a higher iron content within the laterite contributed to an increase in the compressive strength under acidic conditions (LAI (59 MPa) > LAC (48 MPa)) compared to the behavior obtained under alkaline conditions (LAI (6 MPa) < LAC (29 MPa)). Accordingly, the acidic products exhibited a dense structure (with lower porosity) and contained amorphous iron/aluminium phosphate phases such as berlinite (FePO{sub 4}), iron hydrogen phosphate hydrate (Fe{sub 3}H{sub 15}(PO{sub 4}){sub 8·}4H{sub 2}O), ferrowyllieite (AlFe{sub 2}Na{sub 2}(PO{sub 4}){sub 3}) and sodium iron phosphate (Na{sub 3}Fe{sub 2}(PO{sub 4}){sub 3}) arising from the alteration of iron minerals in an acidic medium, confirmed by Mössbauer spectroscopy and electron paramagnetic resonance spectroscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Chemical degradation of fly ash blended concrete with the seasonal variation of rainwater in a radioactive waste repository: A thermodynamic modeling approach

Highlights: • The thermodynamic model for the cementitious system was successfully developed. • The chemical degradation of concrete was greatly affected by rainwater types. • Inorganic carbon species in rainwater reduced the chemical resistance of concrete. • The durability of concrete to rainwater decreased with increasing fly ash content. This study presents a long-term degradation behavior of fly ash blended concrete in a vault type low- and intermediate-level radioactive waste (LILW) repository by thermodynamic equilibrium calculations using PHREEQC combined with CEMDATA18 database. Since rainwater plays a predominant role as leachate for the concrete waste container in the repository, the effect of chemical properties of seasonal rainwater on the chemical degradation of concrete was analyzed. In addition, the impact of the blending with fly ash on the chemical degradation was evaluated through a gradual replacement of ordinary Portland cement (OPC) by fly ash. Regardless of the replacement level, autumn rainwater showed the greatest influence on the concrete degradation owing to the presence of inorganic carbon species, which induce the carbonation. The resistance of concrete to chemical degradation by rainwater was persistently reduced due to the decreasing formation of portlandite and calcium silicate hydrate (C-S-H) with increasing replacement level.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Atomic structure and phase assemblages in novel M-(N)-A-S-H materials

This paper investigates the atomic structure and phase assemblages in new sodium-stabilized magnesium aluminosilicate hydrate (M-(N)-A-S-H) cementitious binders. Results indicate that in the absence of Ca{sup 2+}, Mg{sup 2+} promotes a binder atomic structure of Si-Al tetrahedral sheets and octahedral Mg sheets with hydrated Na{sup +} cations likely in the interlayer sites similar to trioctahedral micas (phyllosilicates). NMR studies verify the incorporation of Al in tetrahedral silicate sheets. XRD demonstrates the ability of these regions to nucleate and form zeolites (i.e., sodalite) as well as the formation of Mg-Al layered double hydroxide (LDH) phases (i.e., meixnerite), which is expected due to high concentrations of Mg and Al. TGA results indicate that M-(N)-A-S-H possesses chemically bound water and hydroxyl units similar to other Mg binders. These results evince the critical role of Mg to form unique atomic structures and durability-linked phases in low-calcium alkali-activated materials.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Preferred orientation of calcium aluminosilicate hydrate compacts: Implications for creep and indentation

Nano/micro-indentation has been extensively used to examine elastic properties and creep of cement-based materials. However, there have been inconsistencies in the measured elastic moduli and debate on the creep mechanism of calcium (alumino) silicate hydrates (C-(A-)S-H). To bring new insights, we examined the deviatoric stress-induced preferred orientation of calcium aluminosilicate hydrate (C-A-S-H), portlandite, and ettringite compacts, using synchrotron-based X-ray diffraction. Intense preferred orientations were observed in C-A-S-H compacts, and the c-axis of unit cells is highly aligned with the compression direction; weaker c-axis related fiber-type texture formed in portlandite and ettringite. Higher humidity, greater compacting pressure, and/or increased duration of the pressure intensified the C-A-S-H preferred orientation, which is facilitated by gel-pore water lubrication. This pressure-induced time-dependent preferential re-orientation of crystallites can contribute to the creep of cement-based materials, and it may cause overrepresentation of the soft c-axis of C-(A-)S-H unit-cell in nanoindentation experiments and underestimation of Young's modulus.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Effect of ZnO on the whiteness of white Portland cement clinker

The addition of ZnO to significantly improve the Hunter whiteness of white Portland cement (WPC) clinkers is introduced in this paper. The effects of ZnO on the whiteness of WPC were studied by chroma analysis, X-ray diffraction (XRD), the Rietveld method, hydration heat measurements and SEM-EDS. The results showed that adding ZnO increased the visible light reflectance, increased the brightness (L{sup ⁎}), and reduced the yellowness (b{sup ⁎}) of WPC clinker with high Fe{sub 2}O{sub 3}. Therefore, ZnO can increase the whiteness of WPC clinker. Zn was mainly distributed in the amorphous phase and unquantifiable crystalline phase (ACn), and then dissolved in the silicate phase. ZnO stabilized R-C{sub 3}S, reduced the crystallization of C{sub 3}A, and increased the ACn content. ZnO increased the amount of Fe in the ACn and minerals, thereby reducing the formation of C{sub 4}AF and improving whiteness. ZnO increased the accumulated heat of hydration but prolonged the induction period. This method provides a new approach for the WPC industry to broaden sources of raw materials and improve product quality.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Deterioration mechanism of alkali-activated materials in sulfuric acid and the influence of Cu: A micro-to-nano structural, elemental and stable isotopic multi-proxy study

In this study, a multi-proxy approach combining {sup 29}Si, {sup 27}Al and {sup 1}H MAS-NMR, FEG-EPMA, XANES at the Cu K-edge and XRD analytics with hydrochemical tools such as ICP-OES analyses, oxygen-isotope signatures, and thermodynamic modelling was applied to K-silicate-activated metakaolin specimens - with and without CuSO{sub 4}·5H{sub 2}O addition - exposed to sulfuric acid at pH = 2 for 35 days. The results revealed a multistage deterioration mechanism governed by (i) acid diffusion, (ii) leaching of K-A-S-H, (iii) microstructural damage related to precipitation of expansive (K,Ca,Al)-sulfate-hydrate phases (iv) complete dissolution of the K-A-S-H framework, (v) and formation of silica gel in the outermost corroded regions. Copper ions were mainly located in layered spertiniite-chrysocolla-like phases in the as-cured materials. The results demonstrate an overall negative effect of Cu addition on chemical material durability, implying that the reported higher durability of Cu-doped AAM in biocorrosion environments can be best explained by bacteriostatic effects.

36 MATERIALS SCIENCE↗
DOE OSTI2021

From casting to 3D printing geopolymers: A proof of concept

The objective of this paper is to define a mix design strategy allowing the implementation of geopolymer in powder bed 3D printing. In a selective binder approach, an aluminosilicate powder bed is activated through the deposit of an alkaline silicate solution. We first show that, in comparison to casting, this technology requires mastering the spreading of the liquid into the powder bed to ensure that the reaction takes place where it is needed. A series of experiments at the drop level, mimicking the 3D printing process, were performed to determine the printing solution composition for a given powder bed packing. We then highlight the relationship between the compressive strength of the printed geopolymer and the powder bed saturation, controlled by the printing parameters. Finally, SEM/EDX analysis confirm the formation of geopolymer with desired Si/Al and Na/Al ratios in the resulting printed material.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Reaction kinetics during early hydration of calcined phyllosilicates in clinker-free model systems

Investigations of nearly pure, calcined phyllosilicates (“meta-phyllosilicates”) in clinker-free model systems were performed in presence and absence of sulfate. Calorimetric investigations show a pronounced reaction during the early reaction period only for metakaolin. Quantitative in situ X-ray diffraction reveals calcium silicate hydrate formation in the systems with metakaolin and metaillite, but not in those with metamuscovite. Ettringite crystallizes in all systems containing sulfate, where only the metakaolin system reaches the maximum ettringite content possible. The amount of aluminum ions released from 2:1 meta-phyllosilicates seems to be insufficient to reach the maximum content. Differences in portlandite dissolution and bound water indicate adsorption effects of calcium or calcium – sulfate ion pair complexes on surfaces of the calcined clay particles. Thus, the chemical as well as the physical influence of the meta-phyllosilicates must be considered to predict the reaction kinetics of calcined clays during early hydration.

36 MATERIALS SCIENCE↗