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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Electrochemical Production of Calcium Hydroxide from Calcium Carbonate [Poster]

Cement production involves the decomposition of limestone (calcium carbonate) at high temperatures (~900°C) to produce CaO, a major constituent in Portland cement (60-70%). Our unique approach will eliminate the high temperature process and introduce a low-temperature electrochemical process to produce Ca(OH) 2 which can be converted into CaO through dehydration process. This program will allow SRNL to become a leading organization in an open and unexplored field that addresses many of the technical challenges.

36 MATERIALS SCIENCE↗
DOE OSTI2025

University of Miami G-band Vapor Radiometer Calibration (UMGVR_CAL) Field Campaign Report

Cold-air outbreak (CAO) clouds in the Arctic are commonly mixed-phase (MP); however, the partitioning of the amount of ice and water in CAO clouds and precipitation is not always well observed. Understanding how cloud phases partition as a function of cloud life cycle is important for predicting snowfall rates, convective life cycle, and intensity at weather timescales. The partitioning into liquid versus ice also has radiative impacts that are consequential for climate. These concerns motivated the incorporation of an airborne G-band vapor radiometer (GVR) into an National Science Foundation-supported aircraft campaign named the Cold Air outbreak Experiment in the Sub-Arctic Region (CAESAR). The GVR is an upward-pointing passive microwave radiometer using four frequencies centered around the 183.31 GHz water vapor absorption line, displaced by +- 1, 3, 7, and 14 GHz. For context, The U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) user facility operates a surface-based GVR at its North Slope of Alaska (NSA) site. The same GVR has been used previously for a field campaign in the southeast Pacific, where an offset was noticed between brightness temperatures (Tbs) measured under clear skies compared to those calculated from a radiative transfer model. To account for any calibration offsets to the Tbs, a request was made to DOE to allow the GVR to operate at ARM’s Southern Great Plains (SGP) observatory and enable comparisons between its measurements and those available at SGP. This request was granted, titled ‘UMGVR_CAL’, short for ‘UMGVR_Calibration’. From October 30 to November 10, 2023, the GVR was deployed to the ARM SGP site to take advantage of their regular, nearby radiosonde launches under clear-sky conditions. The latter were determined using the SGP total sky imagery data. The GVR brightness temperatures in these clear-sky conditions were compared to those calculated by a radiative transfer code (PAMTRA) based on the SGP radiosondes. During the campaign, four suitable clear-sky episodes could be used for the GVR calibration. While few in number, these proved to be enough to satisfy our goal.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Cyclotron production of 43Sc and 44gSc from enriched 42CaO, 43CaO, and 44CaO targets

Introduction: 43 Sc and 44g Sc are both positron-emitting radioisotopes of scandium with suitable half-lives and favorable positron energies for clinical positron emission tomography (PET) imaging. Irradiation of isotopically enriched calcium targets has higher cross sections compared to titanium targets and higher radionuclidic purity and cross sections than natural calcium targets for reaction routes possible on small cyclotrons capable of accelerating protons and deuterons. Methods: In this work, we investigate the following production routes via proton and deuteron bombardment on CaCO 3 and CaO target materials: 42 Ca(d,n) 43 Sc, 43 Ca(p,n) 43 Sc, 43 Ca(d,n) 44g Sc, 44 Ca(p,n) 44g Sc, and 44 Ca(p,2n) 43 Sc. Radiochemical isolation of the produced radioscandium was performed with extraction chromatography using branched DGA resin and apparent molar activity was measured with the chelator DOTA. The imaging performance of 43 Sc and 44g Sc was compared with 18 F, 68 Ga, and 64 Cu on two clinical PET/CT scanners. Discussion: The results of this work demonstrate that proton and deuteron bombardment of isotopically enriched CaO targets produce high yield and high radionuclidic purity 43 Sc and 44g Sc. Laboratory capabilities, circumstances, and budgets are likely to dictate which reaction route and radioisotope of scandium is chosen.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Distribution of Lanthanides, Yttrium, and Scandium in the Pilot-Scale Beneficiation of Fly Ashes Derived from Eastern Kentucky Coals

In this study, Central Appalachian coal-derived fly ashes from two power plants were beneficiated in a pilot-scale facility in order to produce a product with a relatively consistent concentration of rare earth elements (REE). The <200-mesh final fly ash product was produced by removing the carbon- and Fe-rich particles prior to screening at 200 mesh (75 µm). The Plant D fly ash had high concentrations of CaO and SO3, which were diminished through the two months when the ash was being beneficiated, representing a consequence of the heat, humidity, and excessive rainfall in the Kentucky summer. The high CaO and SO3 concentrations through the early runs likely contributed to the lower REE in the <200-mesh products of those runs. Of the non-REE minor elements, Ba, V, Mn, Zn, and As showed the greatest between-run variations within the runs for each plant. The overall REE concentrations proved to be similar, both on a between-run basis for the individual fly ash sources and on a between-plant basis. Variations in fly ash quality will occur in larger-scale operations, so on-going attention to the fly ash quality and the response of the fly ash to beneficiation is necessary. Changes in the Plant D fly ash with time imply that both the freshness of the original ash and the length and conditions of its storage at the site of beneficiation could be factors in the quality and consistency of the processed fly ash.

58 GEOSCIENCES↗
DOE OSTI2024

Understanding aerosol–cloud interactions using a single-column model for a cold-air outbreak case during the ACTIVATE campaign

Marine boundary layer clouds play a critical role in Earth's energy balance. Their microphysical and radiative properties are highly impacted by ambient aerosols and dynamic forcings. In this study, we evaluate the representation of these clouds and related aerosol–cloud interaction processes in the single-column version of the E3SM climate model (SCM) against field measurements collected during the NASA ACTIVATE campaign over the western North Atlantic, as well as intercompare results with high-resolution process level models. We show that E3SM SCM reproduces the macrophysical properties of post-frontal boundary layer clouds in a cold-air outbreak (CAO) case well. However, it generates fewer but larger cloud droplets compared to aircraft measurements. Further sensitivity tests show that the underestimation of both aerosol number concentration and vertical velocity variance contributes to this bias. Aerosol–cloud interactions are examined by perturbing prescribed aerosol properties in E3SM SCM with fixed dynamics. Higher aerosol number concentration or hygroscopicity leads to more numerous but smaller cloud droplets, resulting in a stronger cooling via shortwave cloud forcing. This apparent Twomey effect is consistent with prior climate model studies. The cloud liquid water path shows a weakly positive relation with cloud droplet number concentration due to precipitation suppression. This weak aerosol effect on cloud macrophysics may be attributed to the dominant impact of strong dynamical forcing associated with the CAO. Our findings indicate that the SCM framework is a key tool to bridge the gap between climate models, process level models, and field observations to facilitate process level understanding.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1973

Removal of a constraint on the composition of the lunar interior.

Ringwood and Essene (1970) proposed that the CaO and Al2O3 contents of the deep interior of the moon must be less than 6% each. This constraint has been generally accepted and has led to models of the lunar interior that are dominated by ferromagnesium silicates. This constraint is invalid. High CaO and Al2O3 peridotites have broader intermediate-density (3.3-3.4 g/cu cm) fields than the Ringwood-Essene 'lunar pyroxenite,' and the high-density phase occurs at higher pressure. Likewise, the gabbro-eclogite transformation pressure increases with Al2O3 content. The moon can have a thick plagioclase rich outer shell and a high Ca-Al interior.

Anderson, D. L.↗
NASA NTRS1983

Improved performance thermal barrier coatings

Thermal barrier coatings offer an attractive approach to improving the durability and efficiency of the hot section of heat engines. The coatings typically consist of an inner alloy bond coating about 0.01 cm thick resistant to oxidation and hot corrosion and an outer ceramic layer, usually a stabilized zirconia, 0.01-0.05 cm thick. Here, the materials, thermomechanical stress, and hot corrosion problems associated with thermal barrier coatings are reviewed along with the capabilities and limitations of current technology. The coatings discussed include ZrO2-Y2O3/NiCrAlY, ZrO2-Y2O3/NiCoCrAlY, ZrO2-MgO/NiCoCrAlY, CaO-SiO2/Co-Cr-Al-Y, and CaO-SiO2/NiCrAlY systems. It is emphasized that the performance of thermal barrier coatings is governed by many complex and interrelated factors, so that optimization of these coatings always involves certain tradeoffs.

Levine, S. R.↗
NASA NTRS1983

Evidence for relict grains in chondrules of Qingzhen, an E3 type enstatite chondrite

Petrographic and chemical studies of the Qingzhen chondrite strongly suggest that it is the most highly unequilibrated (type 3) enstatite chondrite recognized so far. Qingzhen contains abundant, well-defined chondrules, some of which were incompletely molten during the chondrule formation process. The relict olivine grains within these chondrules contain dusty inclusions of almost pure metallic Fe, which appear to be the in situ reduction product of the fayalitic component of the olivine. The reduction process presumably took place at the time of chondrule formation and the chondrule precursor material must have been more oxidized than average enstatilite chondrite material. It is believed that this oxidized material may have formed at the enstatite chondrite formation location in the solar nebula, provided fluctuations in the degree of oxidation of the nebular gas existed at such locations. Reheating of this material under more reducing conditions would lead to the observed reduction of the olivine. Igneous olivines within chondrules always contain detectable amounts of CaO, while relict olivines are essentially CaO-free. This seems to suggest thatg the relict olivines did not originate during a previous igenous process of chondrule formation and might represent condensation products from the early solar nebula.

Rambaldi, E. R.↗
NASA NTRS1984

Chemical and physical studies of type 3 chondrites. III Chondrules from the Dhajala H3.8 chondrite

Thermoluminescence (TL) properties have been measured in 58 chondrules separated from the Dhajala H3.8 chondrite. The pyrolytic chondrules are noted to have higher mass-normalized TL values than nonpyrolytic ones. Significant correlations are noted between log(TL) and the bulk CaO, Al2O3, and MnO content of the chondrules. These, together with correlations of log(TL) with the CaO, Al2O3, SiO2 and normative anorthite content of the chondrule glass, indicate an association of the TL and the abundance and position of mesostasis. It is suggested that the TL level in a given chondrule is governed by its bulk composition and metamorphism, and it is hypothesized that the devitrification resistance of unequilibrated chondrule mesostasis explains the unequilibration of certain chondrules in type 3 ordinary chondrites.

Sears, D. W. G.↗
NASA NTRS1984

Achondrite ALHA77005 - Alteration of chromite and olivine

The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt pct; (spinel) P2O5 3.5, SiO2 2.1, TiO2 2.2, Al2O3 2.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt pct. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33-35, FeO 30-28, MgO 28-32, sum 93 wt pct. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stoeffler, 1980). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for preterrestrial alteration.

Smith, J. V.↗
NASA NTRS1986

Determination of CA-41, I-129 and OS-187 in the Rochester tandem accelerator and some applications of these isotopes

The measurement of Ca-41 and I-129 utilizing the Rochester Tanden Accelerator Mass Spectrometer (TAMS) is discussed. Ca-41, having a half-life of 100,000 yrs., is of potential use for the dating of ground water as well as of bones in the age range between 50,000 and 1 million yrs. A major problem for the measurement of Ca-41 with TAMS is the fact that calcium does not readily form negative atomic ions. It does, however, form negative molecular ions. The production of CaO ions from compounds such as CaO and CaCO3 and from free Ca molecules sprayed with oxygen gas was studied. A project to utilize I-129 as a tracer for hydrothermal convection in sediment-covered oceanic crust is also briefly described. Finally, plans to use the Os-187/Os-186 ratio for the determination of extraterrestrial material in the Ries crater in Germany are summarized.

Fehn, U.↗
NASA NTRS1990

Parental magmas of Mare Fecunditatis - Evidence from pristine glasses

Results are presented on the petrography and electron microprobe analyses of 14 discrete glass beads from the Luna 16 core sample (21036,15) from Mare Fecunditatis regolith, that were previously characterized as representing pristine glasses. Compared to Apollo pristine glasses analyzed by Delano (1986), the Luna 16 pristine glasses have higher CaO and Al2O3 contents but lower MgO and Ni. On the basis of their contents of MgO, FeO, Al2O3, and CaO, these pristine glasses could be divided into two groups, A and B. It is suggested that at least two parental magmas are needed to explain the chemical variations among these glasses. The Group B glasses appear to represent primitive parental magma that evolved by olivine fractionation to the compositions of the Luna 16 aluminous mare basalts, whereas the Group A volcanic glasses may represent an unusual new basalt magma type that contains a high plagioclase component.

Jin, Y.↗
NASA NTRS1992

Thermochemical energy storage for a lunar base

A thermochemical solar energy storage concept involving the reversible reaction CaO + H2O yields Ca(OH)2 is proposed as a power system element for a lunar base. The operation and components of such a system are described. The CaO/H2O system is capable of generating electric power during both the day and night. Mass of the required amount of CaO is neglected since it is obtained from lunar soil. Potential technical problems, such as reactor design and lunar soil processing, are reviewed.

Perez-Davis, Marla E.↗
NASA NTRS1992

Adsorption of CO on oxide and water ice surfaces - Implications for the Martian atmosphere

The adsorption of carbon monoxide (CO) on water ice and on the oxides Fe2O3, Fe3O4, Al2O3, SiO2, CaO, MgO, and TiO2 (rutile and anatase) has been investigated in a flow reactor. A mass spectrometer was employed as a detector to monitor the temporal concentrations of CO. Adsorption coefficients as large as 1 x 10 exp -4 were measured for CO on TiO2 solids in helium at 196 K. The fractional surface coverage for CO on TiO2 solids in helium was also determined to be approximately 10 percent at 196 K. The upper limits of the fractional surface coverage for the other oxides (Fe2O3, Fe3O4, Al2O3, SiO2, CaO, and MgO) and water ice were also measured to be less than 1 percent. The implications for the stability of CO2 in the Martian atmosphere and the 'CO hole' observed by the Phobos/ISM experiment are discussed.

Leu, M.-T.↗
NASA NTRS1992

Chemical variation and zoning of olivine in lunar dunite 72415 - Near-surface accumulation

Electron microprobe remeasurements have been used to reevaluate the range of olivine compositions, including CaO, in lunar dunite sample 72415 and compare that range with olivines in established plutonic rocks. Olivines from ferroan anorthosite 62237 and samples from the Stillwater intrusion were analyzed; literature data for other lunar and terrestrial plutonic samples were used for comparisons. The analyses show that the lunar dunite 72415 contains a range of olivine compositions, that the olivines are zoned, and that they have CaO abundances that are consistent with shallow hypabyssal rather than deep plutonic accumulation.

Ryder, Graham↗
NASA NTRS1994

Phase E in a water-saturated peridotite system at 9.3 GPa

The stability of hydrous phases in a natural upper mantle system has been investigated at 9.3 GPa using a gel of KLB-1 peridotite composition with brucite which contains 14 wt. percent (30 atom. percent) water. No hydrous mineral was found at 950 (+150 -50) degree C. At 800 degree C, an assemblage of phase A, phase E, enstatite, clinohumite, and garnet is obtained. Although there is a significant thermal gradient over the sample, phase E is found to be surrounded by phase A in the lower temperature part. Electron probe analyses show that phase E has 35.5 SiO2, 4.4 Al2O3, 41.1 MgO and 8.5 wt. percent FeO* (Mg value is 90) with an oxide sum of 89.7 wt. percent, and possesses a stoichiometry similar to that proposed by Kanzaki. CaO and TiO2 are both less than 0.1 wt. percent. Coexisting phase A has 0.5 wt. percent CaO but only 0.4 wt. percent Al2O3 concentration. Phase A coexists with only enstatite in the water-saturated MgO-FeO-SiO2 system at 800 degree C and 9.3 GPa as well as the results in the water-saturated MgO-SiO2 system. Therefore it is suggested that the addition of Al2O3 expands the stability field of phase E to lower than 13 - 17 GPa in the water-saturated MgO-SiO2 system.

Kawamoto, Tatsuhiko↗
NASA NTRS1994

Orthopyroxene as a recorder of primitive achondrite petrogenesis: Major-, minor-, and trace-element systematics of orthopyroxene in Lodran

Considerable attention has been paid recently to the primitive achondrites because they may form a link between chondrites and more differentiated achondrite meteorites. A recent paper by Miyamoto and Takeda addresses the thermal history of lodranites Yamato 74357 and MAC 88177 as inferred from chemical zoning of pyroxene and olivine determined by electron microprobe analyses. Their results suggested that interstitial melt was present and then extracted. We have taken the analysis of Lodran-type meteorites one step further by incorporating the techniques of Electromagnetic Pulse/Wavelength Dispersive Spectroscopy (EMP/WDS) compositional imaging and scanning ion mass spectroscopy (SIMS) analysis. Orthopyroxene in Lodran is strongly zoned in CaO, Al2O3, TiO2, and Cr2O3 within the last 10-30 microns from the grain boundaries. The rims are reversely zoned in Mg-Fe, exhibiting Mg enrichment, and compositions change from a fairly uniform Wo3En94 within the grains to Wo1En96 at the rims. CaO drops from 1.6 to 0.6 wt% and Al2O3, TiO2, and Cr2O3 exhibit similar depletions. MnO is fairly uniform throughout the grains at around 0.5 wt%. Olivine is also reversely zoned with respect to not only grain boundaries but also to fractures within the grains, giving many olivine grains a complex, patchy zoning pattern. Some of the core-rim trace-element systematics for orthopyroxene are illustrated. Because of the rather narrow zoned rims in Lodran orthopyroxene and the low trace-element abundances, it is difficult to clearly resolve the trace-element systematics. Nevertheless it is evident that the cores are enriched in the incompatible trace elements Ce, Nd, Dy, Er, Yb, Y, and Zr relative to the rims.

Papike, J. J.↗
NASA NTRS1993

High-Pressure Equation of State for Partially Ionic Solids

Recently, we showed that the cohesive energy of partially ionic solids may be characterized by a two-term energy relationship consisting of a Coulomb term arising from the valence-charge transfer delta Z between the atoms, and a scaled universal energy function E(sup *)(a(sup *)), which accounts for the partially covalent character of the bond and for the repulsion between the atomic cores for small R; a(sup *) is a scaled length. Normalized cohesive-energy curves of alkali halide crystals and of Ti and Ag halide crystals were obtained, and the cohesive-energy-curve parameters were used to generate theoretical equation-of-state (EOS) curves for the Li, Na, K, Cs, and Ag halides. Good agreement was obtained with the experimental isothermal compression curves over a wide pressure range (0-90 kbar). In this paper we verify that the cohesive-energy relationship is valid for divalent partially ionic solids; physically reasonable charge-transfer values (1.80 less than delta Z less than 2.0) are obtained for MgO, CaO, and CaS. Next, EOS curves for LiF, NaF, Nal, CsCl, Csl, MgO, CaO, and CaS are generated in terms of the cohesive-energy parameters. These EOS's yield excellent fits to experimental isothermal-compression data and to shock-wave data to very high pressures (P(sub max)= 250-1350 kbar).

Schlosser, Herbert↗