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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one K2O sheet oriented in the (0, 0, 1) direction. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a trigonal non-coplanar geometry to three equivalent O2- atoms. All K–O bond lengths are 2.71 Å. In the second K1+ site, K1+ is bonded in a 3-coordinate geometry to four equivalent O2- atoms. There are three shorter (2.67 Å) and one longer (3.21 Å) K–O bond lengths. O2- is bonded in a 7-coordinate geometry to seven K1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O is beta Vanadium nitride-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There are one shorter (2.66 Å) and two longer (2.70 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There are a spread of K–O bond distances ranging from 2.67–2.70 Å. O2- is bonded to six K1+ atoms to form a mixture of distorted corner and edge-sharing OK6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. K1+ is bonded to four equivalent O2- atoms to form a mixture of corner and edge-sharing KO4 tetrahedra. All K–O bond lengths are 2.81 Å. O2- is bonded in a body-centered cubic geometry to eight equivalent K1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O is Hydrophilite-like structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. K1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. There are two shorter (2.68 Å) and one longer (2.71 Å) K–O bond lengths. O2- is bonded to six equivalent K1+ atoms to form a mixture of edge and corner-sharing OK6 octahedra. The corner-sharing octahedral tilt angles are 53°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O crystallizes in the trigonal P3 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.83–3.06 Å. In the second K1+ site, K1+ is bonded to four O2- atoms to form a mixture of distorted corner and edge-sharing KO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.63–2.89 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to six K1+ atoms. In the second O2- site, O2- is bonded in a 9-coordinate geometry to nine K1+ atoms. In the third O2- site, O2- is bonded in a 9-coordinate geometry to nine K1+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Diffusion in the system K2O-SrO-SiO2. II - Cation self-diffusion coefficients.

The self-diffusion coefficients were measured by introducing a slab of glass previously irradiated in a reactor between two slabs of unirradiated glass. By heating the specimens, etching them sequentially and determining the radioactivity, self-diffusion coefficients for K and Sr were measured. It is pointed out that the results obtained in the investigations appear to support the proposal that the network of the base glass predominantly controls the activation energy for the diffusion of ions.

Varshneya, A. K.↗
NASA NTRS1971

Bulk, rare earth and other trace elements in Apollo 14 and 15 and Luna 16 samples

The chemical abundances were measured by instrumental and radiochemical neutron activation analysis in a variety of lunar specimens. Apollo 14 soils are characterized by significant enrichments of Al2O3, Na2O and K2O and depletions of TiO2, FeO, MnO and Cr2O3 relative to Apollo 11 and to most of Apollo 12 soils. The uniform abundances in 14230 core tube soils and three other Apollo 14 soils indicate that the regolith is uniform to at least 22 cm depth and within approximately 200 m from the lunar module. Two Luna 16 breccias are similar in composition to Luna 16 soils. Four Apollo 15 soils (LM, STA 4, 9, and 9a) have variable compositions. Interelement correlations between MnO-FeO, Sc-FeO, V-Cr2O3 and K2O-Hf negate the hypothesis that howardite achondrites may be primitive lunar matter, argue against the fission hypothesis for the origin of the moon, and precludes any selective large scale volatilization of alkalies during lunar magmatic events.

Laul, J. C.↗
NASA NTRS1972

Compositional data for twenty-one Fra Mauro lunar materials.

Major, minor, and trace element analyses are presented for two igneous rocks, six breccias, four microbreccias, two breccia clasts, and six soils, as well as a sample of sawdust from rock 14066. Evaluation of the data suggests that the samples from the Fra Mauro highlands have the same nonterrestrial characteristics shown previously by the samples returned from the mare regions by Apollo 11 and 12 - namely, a high refractory element content, a lower volatile element content, and an excess reducing capacity above that due to FeO. The Fra Mauro soils have higher concentrations of Al2O3, Na2O, and K2O and lower amounts of FeO and TiO2 than do the mare soils. They also show a bimodal distribution of Ni, B, and Nb. The highland breccias are richer in SiO2, Al2O3, MgO, Na2O, and K2O than those returned from the mare lowlands. FeO, TiO2, and MnO are lower in concentration at Fra Mauro, and the highland breccias are more complex mineralogically than those collected previously.

Rose, H. J., Jr.↗
NASA NTRS1973

Crystallization of plagioclase in mare basalts

A detailed study has been made of the morphology, zoning and major- and minor-element chemistry of plagioclase in mare basalt 12021 and for comparison, in several other mare basalts. Two types of plagioclase can be distinguished based on growth rate as expressed by the formation of hollow as opposed to lath-shaped crystals. The liquidus plagioclase is the most sodic part of the hollow crystals and is more sodic than the lath-shaped crystals. Hollow grains show oscillatory zoning, whereas the lath-shaped grains show normal zoning. The ratios FeO/(FeO + MgO) and K2O/(K2O + Na2O) increased in both types of plagioclase as they grew, and these ratios can be used as a guide to the crystallization history of the plagioclase. The FeO/(FeO + MgO) ratios are similar to those of coprecipitating pyroxene. The data presented here suggest the onset of plagioclase nucleation is primarily controlled by magma composition, and the point at which the magma becomes supersaturated with plagioclase.

Crawford, M. L.↗
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 NTRS1988

Pan-African alkali granites and syenites of Kerala as imprints of taphrogenic magmatism in the South Indian shield

Granite and syenite plutons with alkaline affinities ranging in age from 550 to 750 Ma sporadically puncture the Precambrian granulites of the Kerala region. All the bodies are small (20 to 60 sq km), E-W to NW-SE elongated elliptical intrusives with sharp contacts and lie on or close to major late Proterozoic lineaments. Geochemical plots of A-F-M and An-Ab-Or relations show an apparent alkali enrichment trend on the former, but the plutons define relatively distinct fields on the latter. Most of the plutons are adamellitic to granitic by chemistry. The variations of SiO2 with log sub 10 K2O/MgO (1) brings out the distinct alkaline nature of the plutons. Some of the granites are extremely potassic, like the Peralimala pluton, which shows up to 11.8 percent K2O. On a SiO2-Al2O3-Na2O+K2O (mol percent) plot, the plutons vary from peraluminous to peralkaline, but none are nepheline normative. Low MgO, low to moderate CaO and high Fe2O3/FeO values are other common characteristics. Among trace elements, depletion of Ba, Sr and Rb with high K/Ba and K/Rb values are typical. Overall, the plutons show a trend of decreasing K/Rb ratio with increasing K content. Individual plutons show more clearly defined trends similar to those from granitic masses characterized by plagioclase fractionation.

Santosh, M.↗
NASA NTRS1992

Geochemistry of HASP, VLT, and other glasses from double drive tube 79001/2

The Apollo 17 double drive tube 79001/2 (station 9, Van Serg Crater) is distinctive because of its extreme maturity, abundance, and variety of glass clasts. It contains mare glasses of both high Ti and very low Ti (VLT) compositions, and highland glasses of all compositions common in lunar regolith samples: highland basalt (feldspathic; Al2O3 greater than 23 wt percent), KREEP (Al2O3 less than 23 wt percent, K2O greater than 0.25 wt percent), and low-K Fra Mauro (LKFM; Al2O3 less than 23 wt percent, K2O less than 0.25 wt percent). It also contains rare specimens of high-alumina, silica-poor (HASP), and ultra Mg glasses. HASP glasses contain insufficient SiO2 to permit the calculation of a standard norm, and are thought to be the product of volatilization during impact melting. They have been studied by electron microprobe major-element analysis techniques but have not previously been analyzed for trace elements. The samples analyzed for this study were polished grain mounts of the 90-160 micron fraction of four sieved samples from the 79001/2 core (depth range 2.3-11.5 cm). A total of 80 glasses were analyzed by SEM/EDS and electron microprobe, and a subset of 33 of the glasses, representing a wide range of compositional types, was chosen for high-sensitivity INAA. A microdrilling device removed disks (mostly 50-100 micron diameter, weighing approx. 0.1-0.5 micro-g) for INAA. Preliminary data reported here are based only on short counts done within two weeks of irradiation.

Lindstrom, D. J.↗
NASA NTRS1994

Origin of tektites

The origin of tektites has been obscure because of the following dilemma. The application of physical principles to the data available on tektites points strongly to origin from one or more lunar volcanoes; but few glasses of tektite composition have hitherto been reported from the lunar samples. Instead, the lunar silicic glasses consist chiefly of a material very rich in K2O and poor in MgO. The ratio of K2O/MgO is higher in these glasses than in any tektites reported. The solution of the dilemma seems to come from the study of some recently discovered terrestrial deposits of tektite glass with high values of K2O/MgO at the Cretaceous Tertiary boundary. These glasses are found to be very vulnerable to crystallization into sandine or to alteration to smectite. These end products are known and are more abundant than any terrestrial deposits of tektite glass. It seems possible that, in fact, the moon produces tektite glass, mostly of the high K2O-low MgO type; but on Earth these deposits are destroyed. The much less abundant deposits with lower K and higher Mg are observed because they survive. Other objections to the lunar origin hypothesis appear to be answerable.

O'Keefe, John A.↗
NASA NTRS2000

Growth of Megaspherulites In a Rhyolitic Vitrophyre

Megaspherulites occur in the middle zone of a thick sequence of rhyolitic vitrophyre that occupies a small, late Eocene to early Oligocene volcanic-tectonic basin near Silver Cliff, Custer County, Colorado. Diameters of the megaspherulites range from 0.3 m to over 3.66 m, including a clay envelope. The megaspherulites are compound spherulites. consisting of an extremely large number (3.8 x 10(exp 9) to 9.9 x 10(exp 9)) of individual growth cones averaging 3 mm long by 1.25 mm wide at their termination. They are holocrystalline, very fine- to fine-grained, composed of disordered to ordered sanidine (orthoclase) and quartz, and surrounded by a thin K-feldspar, quartz rich rind, an inner clay layer with mordenite, and an outer clay layer composed wholly of 15 A montmorillonite. Whole rock analyses of the megaspherulites show a restricted composition from their core to their outer edge, with an average analyses of 76.3% SiO2, 0.34% CaO, 2.17% Na2O, 6.92% K2O, 0.83% H2O+ compared to the rhyolitic vitrophyre from which they crystallize with 71.07% SiO2, 0.57% CaO, 4.06% Na2O,4.l0% K2O, and 6.40% H2O+. The remaining oxides of Fe2O3 (total Fe), A12O3, MnO,MgO, TiO2, P2O5, Cr2O3, and trace elements show uniform distribution between the megaspherulites and the rhyolitic vitrophyre. Megaspherulite crystallization began soon after the rhyolitic lava ceased to flow as the result of sparse heterogeneous nucleation, under nonequilibrium conditions, due to a high degree of undercooling, delta T. The crystals grow with a fibrous habit which is favored by a large delta T ranging between 245 C and 295 C, despite lowered viscosity, and enhanced diffusion due to the high H2O content, ranging between 5% and 7%. Therefore, megaspherulite growth proceeded in a diffusion controlled manner, where the diffusion, rate lags behind the crystal growth rate at the crystal-liquid interface, restricting fibril lengths and diameters to the 10 micron to 15 micron and 3 micron and 8 micron ranges respectively. Once diffusion reestablishes itself at the crystallization front, a new nucleation event occurs at the terminated tips of the fibril cones and a new cone begins to develop with a similar orientation (small angle branching) to the earlier cones. During crystallization, these fibril cones impinge upon each other, resulting in fibril cone-free areas. These cone-free areas consist of coarser, fine-grained phases, dominated by quartz, which crystallized from the melt as it accumulated between the crystallizing K-feldspar fibrils of the cones. The anhydrous nature of the disordered to ordered sanidine (orthoclase) and quartz, suggests that water in the vitrophyre moved ahead of the crystallization front, resulting in a water rich fluid being enriched in Si, K, Na, Mg, Ca, Sr, Ba, and Y. The clay layers associated with the megaspherulites are therefore, the result of the deuteric alteration between the fractionated water and the vitrophyre, as indicated by the presence of the minerals mordenite and montmorillonite. This silica rich fluid also resulted in the total silicification of the megaspherulites within the upper 3 m of the vitrophyre.

Smith, Robert K.↗
DOE OSTI2024

Ensemble methods for quantification of potassium oxide in ChemCam Mars and laboratory spectra

In this paper we test new approaches for predicting the amount of element oxides in rock samples from the ChemCam instrument suite onboard the NASA Curiosity rover by focusing on K 2 O. Using the expanded dataset compiled by Gasda et al. (2021) with and without the Earth to Mars (E2M and NoE2M) transformation discussed in Clegg et al. (2017) we trained blended submodels using the “double blending” technique and compared these to ensemble methods (Random Forest, ExtraTrees, and Gradient Boosting Regression). We found that ensemble methods performed similar to blended submodels when looking at RMSE-P on the laboratory spectra and provided significant advantages when looking at spectra coming from Mars. For the full model, blended submodels achieved an RMSE-P of 0.62 and 0.60 (E2M and NoE2M respectively) while Gradient Boosting Regression resulted in a slightly improved RMSE-P of 0.59 and 0.60. More importantly, by employing a local RMSE-P estimation technique where model performance is evaluated based on nearby test samples we found that using ensemble methods can lower the quantification limit for K 2 O from the current value of ≈0.6 wt% to ≈0.08 wt% using Extra Trees and Random Forest. This would allow for a much larger range of K 2 O values to be quantified on Mars with greater certainty given that most targets seen on Mars tend to have <1 wt% K2O. Finally, we used both Mean Decrease in Impurity (MDI) and permutation importance techniques to investigate the wavelengths used by the ensemble methods and found that they correspond to known potassium emission lines. This suggests that ensemble methods can provide an easier to train and improved alternative to blended submodels for predicting potassium compositions from Laser Induced Breakdown Spectroscopy (LIBS) data.

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

Assessment of Potential Dose and Environmental Impacts from Proposed Testing at the INL Radiological Response Training Range

This assessment uses screening-level models to calculate potential environmental impacts from proposed tests at the Idaho National Laboratory (INL) Radiological Response Training Range (RRTR) site. Proposed tests could be conducted using 11 different radioactive material types that include K2O, LaBr3, KBr, Cu, Zr, F, Ga, Ga2O3, NaNO2, Ga-68, and Tc-99m. The tests could potentially release radioactive material to the atmosphere and radionuclides and other contaminants to the soil, which could leach into the unsaturated zone and migrate to the aquifer. Atmospheric transport of radionuclides to potential human receptors and time-integrated air concentrations were calculated with a Gaussian plume model and three years of hourly meteorological data. Potential surface-soil impacts were calculated with the computer program mixing-cell model (MCM). Groundwater impacts were calculated with the computer programs MCM and GWSCREEN. Radiological doses from potential atmospheric releases were calculated for public receptors off the INL Site and for workers at nearby INL facilities. Results were compared to regulatory dose limits. Maximum potential groundwater concentrations were estimated in the aquifer below the NSTR site and compared to drinking water standards or risk-based screening levels for resident tap water. Soil concentrations were calculated and compared to risk-based screening levels for workers and potential future residents. All impacts were estimated assuming 12 tests are conducted annually using all 11 material types for a period of 15 years. This document provides the resources to enable a subject matter expert in the field of environmental assessments to replicate the modeling and calculations. The methodology and parameters are presented in the text. All electronic files, including computer-code input, output, executable files, batch files, scripts, and spreadsheet files are contained in a zip file that can be accessed by selecting “Additional Information” (select Native File) in the INL Electronic Document Management System (EDMS). It is highly unlikely the test scenarios evaluated in this ECAR will adversely impact human health based on comparisons of calculated dose and concentration against regulatory standards and risk-based screening levels. Conservative estimates of dose to workers and the public from atmospheric transport of possible radionuclide releases are far below federal radiation protection standards. Conservative estimates of potential contaminant concentrations in groundwater are less than federal drinking water standards or screening levels. Predicted radionuclide concentrations in surface soils are below risk-based screening levels, except for Ge-68 (material Ga-68) for the worker. The Ge-68 soil concentration can be made less than the worker PRG, if the number of annual tests using Ga-68 is reduced from 12 to 6. However, the sum of ratios still exceeds one because of the high K-40 ratio. If the EF of the worker (number of days the worker is in the contaminated testing area) is reduced from 225 days/yr (default value for full time worker) to 112 days/yr, the Ge-68 ratio is less than one and the sum of ratios is less than one. Actual radiation doses and groundwater and surface-soil concentrations are likely to be much less than those calculated because of the conservative assumptions and parameters employed in the modeling. For example, atmospheric-transport calculations assume the entire inventory of each material type is readily released to the atmosphere and no plume deposition, depletion, or radioactive decay occurs during transport. The calculations also assume the same meteorological conditions (e.g., wind velocity, wind direction, stability class) that produce the maximum 95th percentile concentration (i.e., concentration representing the 95th percentile of a distribution of concentrations derived from 3 years of hourly meteorological data) at each receptor location are the same for all 12 tests during the year, and each receptor is assumed to be present during all 12 tests. The surface-soil assessment assumes the entire inventory of each test is deposited in the top 5 cm of soil. No atmospheric dispersal is assumed, and the radionuclides are subject only to leaching and radioactive decay. The groundwater-pathway modeling is conservative in that it is one-dimensional in the unsaturated zone (no lateral spreading/dilution) and assumes the entire inventory of contaminants infiltrates into the ground at the same location for every test. This is especially conservative for particulate radionuclides because they would have to dissolve or corrode first and some would be dispersed into the atmosphere. The groundwater receptor is also assumed to consume water directly from a hypothetical well positioned in the location of maximum concentration. In addition, conservative degradation rates were used, and volatilization was not considered for the nonradioactive chemical

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1971

A dunite-norite lunar microbreccia.

An olivine-rich microbreccia with noritic affinities, collected on the Apollo 14 mission to Fra Mauro, is described and analyzed. A photomicrograph (by plain transmitted light) of the microbreccia is discussed. One of three distinct areas on the microbreccia is shown to be a dunite containing over 90% olivine. The other two are more gabbroic in composition, though most of the mineral clasts are olivine. The fine grained matrix material contains significant amounts of K2O and P2O5, suggesting a relation to norites.

Taylor, G. J.↗