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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 Baddeleyite-like structured and crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing KO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.74–2.83 Å. In the second K1+ site, K1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. There are a spread of K–O bond distances ranging from 2.65–2.77 Å. O2- is bonded to seven K1+ atoms to form a mixture of distorted edge and corner-sharing OK7 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O crystallizes in the tetragonal P4_2/nmc space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing KO4 tetrahedra. There are two shorter (2.78 Å) and two longer (2.98 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing KO4 tetrahedra. There are two shorter (2.69 Å) and two longer (2.80 Å) K–O bond lengths. In the third K1+ site, K1+ is bonded in a linear geometry to two equivalent O2- atoms. Both K–O bond lengths are 2.50 Å. O2- is bonded to seven K1+ atoms to form a mixture of distorted edge and corner-sharing OK7 hexagonal 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↗
DOE OSTI2020

Materials Data on K2O by Materials Project

K2O crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a linear geometry to two equivalent O2- atoms. Both K–O bond lengths are 2.56 Å. In the second K1+ site, K1+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All K–O bond lengths are 2.86 Å. O2- is bonded to six K1+ atoms to form a mixture of edge and corner-sharing OK6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2O by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
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 OSTI2020

Materials Data on K2Fe2Co2C12N12O by Materials Project

K2O(Fe)2(Co(CN)6)2 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of two iron molecules, one potassium monoxide molecule, and two Co(CN)6 clusters. In each Co(CN)6 cluster, Co2+ is bonded in an octahedral geometry to six N3- atoms. There are a spread of Co–N bond distances ranging from 2.09–2.15 Å. There are six inequivalent C+2.17+ sites. In the first C+2.17+ site, C+2.17+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. In the second C+2.17+ site, C+2.17+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. In the third C+2.17+ site, C+2.17+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. In the fourth C+2.17+ site, C+2.17+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. In the fifth C+2.17+ site, C+2.17+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. In the sixth C+2.17+ site, C+2.17+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. There are six inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted linear geometry to one Co2+ and one C+2.17+ atom. In the second N3- site, N3- is bonded in a linear geometry to one Co2+ and one C+2.17+ atom. In the third N3- site, N3- is bonded in a linear geometry to one Co2+ and one C+2.17+ atom. In the fourth N3- site, N3- is bonded in a linear geometry to one Co2+ and one C+2.17+ atom. In the fifth N3- site, N3- is bonded in a linear geometry to one Co2+ and one C+2.17+ atom. In the sixth N3- site, N3- is bonded in a linear geometry to one Co2+ and one C+2.17+ atom.

36 MATERIALS SCIENCE↗
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↗