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All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

20 K Helium Refrigeration System for NASA-JSC Chamber-A

A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope. The chamber previously and currently still has helium cryopumping panels (CPP) and LN2 shrouds used to create Low Earth Orbit environments. Now with the new refrigerator and new helium shrouds (45 x 65 ) the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Labs, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate a inverse coefficient of performance better than 70 W/W for a 18 KW load at 20 K (accounting for liquid nitrogen precooling power) that remains essentially constant down to 1/3 of this load. Even at 10 percent of the maximum capacity, the performance is better than 140 W/W at 20K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10kW at 15 K to 100 kW at 100K. The refrigerator is capable of operating at any load temperature from 15K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

Homan, J.↗
NASA NTRS2017

Volatiles in High-K Lunar Basalts

Chlorine is an unusual isotopic system, being essentially unfractionated ((delta)Cl-37 approximately 0 per mille ) between bulk terrestrial samples and chondritic meteorites and yet showing large variations in lunar (approximately -4 to +81 per mille), martian, and vestan (HED) samples. Among lunar samples, the volatile-bearing mineral apatite (Ca5(PO4)3[F,Cl,OH]) has been studied for volatiles in K-, REE-, and P (KREEP), very high potassium (VHK), low-Ti and high-Ti basalts, as well as samples from the lunar highlands. These studies revealed a positive correlation between in-situ (delta)Cl-37 measurements and bulk incompatible trace elements (ITEs) and ratios. Such trends were interpreted to originate from Cl isotopic fractionation during the degassing of metal chlorides during or shortly after the differentiation of the Moon via a magma ocean. In this study, we investigate the volatile inventories of a group of samples for which new-era volatile data have yet to be reported - the high-K (greater than 2000 ppm bulk K2O), high-Ti, trace element-rich mare basalts. We used isotope imaging on the Cameca NanoSIMS 50L at JSC to obtain the Cl isotopic composition [((Cl-37/(35)Clsample/C-37l/(35)Clstandard)-1)×1000, to get a value in per thousand (per mille)] which ranges from approximately -2.7 +/- 2 per mille to +16.1 +/- 2 per mille (2sigma), as well as volatile abundances (F & Cl) of apatite in samples 10017, 10024 & 10049. Simply following prior models, as lunar rocks with high bulk-rock abundances of ITEs we might expect the high-K, high-Ti basalts to contain apatite characterized by heavily fractionated (delta)Cl-37 values, i.e., Cl obtained from mixing between unfractionated mantle Cl (approximately 0 per mille) and the urKREEP reservoir (possibly fractionated to greater than +25 per mille.). However, the data obtained for the studied samples do not conform to either the early degassing or mixing models. Existing petrogentic models for the origin of the high-K, high-Ti basalts do not include urKREEP assimilation into their LMO cumulate sources. Therefore, Cl in these basalts either originated from source region heterogeneity or through assimilation or metasomatism by volatile and incompatible trace element rich materials. The new data presented here could provide evidence for the existence of region(s) in the lunar interior that are ITE-enriched and contain Cl that does not share isotopic affinities with lunar urKREEP, possibly representing the composition of the purported 'neuKREEP'.

Barnes, Jessica J.↗
NASA NTRS2018

Development of a 50 mK - 10 K Flight-Worthy Vibration-Free Continuous Adiabatic Demagnetization Refrigerator

The cryogenics and fluids branch at NASA Goddard Space Flight Center is currently developing a flight-worthy vibration-free 50 mK to 10 K Continous Adiabatic Demagnetization Refrigerator (CADR) that will potentially serve as the cooling scheme for future space flight missions such as OST, LUVOIR, and other flagship missions. This 7 stage CADR will lift 6 microW of heat at its lowest stage and reject heat to a temperature platform at 10 K. A single stage 4 - 10 K flight-worthy ADR unit was recently demonstrated with an optimized cycle time of 132 seconds and a heat lift of ~13 mW at 4 K. We discuss the development progress and details of its desing in this presentation.

ADR↗
NASA NTRS2019

The K Dwarf Advantage for Biosignatures on Directly Imaged Exoplanets

Oxygen and methane are considered to be the canonical biosignatures of modern Earth, and the simultaneous detection of these gases in a planetary atmosphere is an especially strong biosignature. However, these gases may be challenging to detect together in the planetary atmospheres because photochemical oxygen radicals destroy methane. Previous work has shown that the photochemical lifetime of methane in oxygenated atmospheres is longer around M dwarfs, but M dwarf planet habitability may be hindered by extreme stellar activity and evolution. Here, we use a 1D photochemical-climate model to show that K dwarf stars also offer a longer photochemical lifetime of methane in the presence of oxygen compared to G dwarfs. For example, we show that a planet orbiting a K6V star can support about an order of magnitude more methane in its atmosphere compared to an equivalent planet orbiting a G2V star. In the reflected-light spectra of worlds orbiting K dwarf stars, strong oxygen and methane features could be observed at visible and near-infrared wavelengths. Because K dwarfs are dimmer than G dwarfs, they offer a better planet-star contrast ratio, enhancing the signal-to-noise ratio (S/N) possible in a given observation. For instance, a 50 hr observation of a planet at 7 pc with a 15 m telescope yields S/N = 9.2 near 1 m for a planet orbiting a solar-type G2V star, and S/N = 20 for the same planet orbiting a K6V star. In particular, nearby mid-late K dwarfs such as 61 Cyg A/B, Epsilon Indi, Groombridge 1618, and HD 156026 may be excellent targets for future biosignature searches.

Arney, Giada N.↗
NASA NTRS2019

The K Dwarf Advantage for Biosignatures on Directly Imaged Exoplanets

Oxygen and methane are considered to be the canonical biosignatures of modern Earth, and the simultaneous detection of these gases in a planetary atmosphere is an especially strong biosignature. However, these gases may be challenging to detect together in the planetary atmospheres because photochemical oxygen radicals destroy methane. Previous work has shown that the photochemical lifetime of methane in oxygenated atmospheres is longer around M dwarfs, but M dwarf planet habitability may be hindered by extreme stellar activity and evolution. Here, we use a 1-D photochemical-climate model to show that K dwarf stars also offer a longer photochemical lifetime of methane in the presence of oxygen compared to G dwarfs. For example, we show that a planet orbiting a K6V star can support about an order of magnitude more methane in its atmosphere compared to an equivalent planet orbiting a G2V star. In the reflected light spectra of worlds orbiting K dwarf stars, strong oxygen and methane features could be observed at visible and near-infrared wavelengths. Because K dwarfs are dimmer than G dwarfs, they offer a better planet-star contrast ratio, enhancing the signal-to-noise (SNR) possible in a given observation. For instance, a 50 hour observation of a planet at 7 pc with a 15-m telescope yields SNR = 9.2 near 1 µm for a planet orbiting a solar-type G2V star, and SNR = 20 for the same planet orbiting a K6V star. In particular, nearby mid-late K dwarfs such as 61 Cyg A/B, Epsilon Indi, Groombridge 1618, and HD 156026 may be excellent targets for future biosignature searches.

Giada N Arney↗
NASA NTRSDate not supplied

Rolling Horizon with K-Position Search Method for Strategic Deconfliction of Package Delivery UAS

This research focuses on the strategic deconfliction of unmanned aircraft systems (UAS) in an urban package delivery environment with two depots and multiple drop-off locations. Since the formulated mixed-integer nonlinear programming (MINLP) problem is non-deterministic polynomial-time (NP) hard, a heuristic algorithm called "rolling horizon with k-position search (KPS)" is used to compute the departure sequence and scheduled time of departure (STD) of each UAS at a depot, considering temporal constraints at en-route crossing waypoints and depots for strategic deconfliction. The simulation studies show that an increase in the value of k (local neighborhood search) in the KPS reduces the average ground delay at the cost of an increase in the computation time for a given number of UAS, size of the rolling horizon window, and number of depots involved in the local neighborhood search. The studies also show that for a given rolling horizon window, the computation time increases exponentially with an increase in the total number of UAS flights when serial processing the local neighborhood search of KPS (with k > 1) and drops by an order of magnitude upon performing the local neighborhood search of KPS using parallel processing instead of serial processing. The computation time drops with the reduction in air traffic complexity of a scenario for a given number of flights, k (local neighborhood search), and rolling horizon window.

UTM↗
DOE OSTI2023

Modeling the CEBAF Injector at 200 kV: Investigating K-Long Beam Conditions with and without Wien Filter

The upcoming K-Long experiment [1] ain Hall D at Jefferson Lab presents unique beam requirements, featuring a significantly low bunch repetition rate and an unusually high bunch charge. This experiment, which utilizes the CEBAF accelerator in conjunction with the GlueX experimental setup, aims to study strange hadron spectroscopy by measuring the differential cross section and polarizations of produced hyperons such as Λ, Σ, Ξ, and Ω. By directing an intense K-Long beam towards the LD2/LH2 target, new and valuable data can be obtained. To optimize the CEBAF injector specifically for this experiment, we employed Multi-Objective Genetic Optimization (MGO) using General Particle Tracer (GPT) simulations. Through this approach, we determined the optimal magnetic elements and radiofrequency (RF) settings required to achieve a K-Long bunch charge of 0.64 pC at an energy of 200 kV. We conducted simulations with both the Wien Filter turned on and off to examine its impact on the beam. Furthermore, we investigated the transmission efficiency and beam characteristics of electron beams with varying charge per bunch through the injector, considering the simultaneous operation of all four CEBAF Halls. The results of our study offer valuable insights and guidance for optimizing the CEBAF injector not only for the Jefferson Lab K-Long experiment but also for other experiments that entail similar beam conditions.

Pokharel, Sunil↗
DOE OSTI2024

Measurement of the Photoproduction Cross-Section of f1(1285) in the Exclusive Reactions p¿ p'K±KSp± AT 7.5 < E¿ < 11.5 GeV with GlueX at Jefferson Lab

The f1(1285) meson is commonly understood to belong to the axial-vector nonet as the low-mass isoscalar partner to the f1(1420) but has been suggested as a candidate for a KK?+c.c molecule. A nearly mass-degenerate 0?+ state has been observed in ? p scattering that calls into question the established branching ratios of the f1(1285) decays. Recently, the differential cross-section for the photoproduction of f1(1285) was measured by the CLAS experiment and the results disagreed with theoretical predictions. Additionally, the CLAS experiment did not observe a mass-degenerate 0?+ state. We present the results of the first photoproduction cross-section measurement d?/dt of f1(1285) at 7.5 < E? < 11.5 GeV from the GlueX experiment at Thomas Jefferson National Accelerator Facility in the reactions ? p ? p?K?Ks?+ and ? p ? p?K+Ks??. We find that the production mechanism of f1(1285) is consistent with t-channel exchange. We also observe a difference in the differential cross-section of f1(1285) as a function of ?t as measured in the charge conjugated K?Ks?± decay modes that we hypothesize to be due to baryonic N? interference. The observed distributions of M(KK) and M(K?) are consistent with both a q ¯ q state and predictions for a KK?+c.c molecular state. Additionally, we find that the cross-section at low M(KK?) is dominated by the 1++ state.

Viducic, Tyler↗
DOE OSTI2023

Search for the lepton-flavour violating decays B 0 → K *0 τ ± μ ∓

A first search for the lepton-flavour violating decays B 0 → K*0 τ ± μ ∓ is presented. The analysis is performed using a sample of proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018, corresponding to an integrated luminosity of 9 fb –1 . No significant signal is observed, and upper limits on the branching fractions are determined to be B (B 0 → K* 0 τ + μ – ) < 1.0(1.2) x 10 –5 and B(B 0 → K* 0 τ – μ + ) < 8.2(9.8) x 10 –6 at the 90% (95%) confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Strong constraints on the b → sγ photon polarisation from B0 → K*0e+e-decays

An angular analysis of the B 0 → K* 0 e + e - decay is performed using a data sample corresponding to an integrated luminosity of 9 fb - 1 of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared ( q 2 ) interval between 0 . 0008 and 0 . 257 GeV 2 , where the rate is dominated by the B 0 → K * 0 γ transition with a virtual photon. The fraction of longitudinal polarisation of the K * 0 meson, F L , is measured to be F L = (4 . 4 ± 2 . 6 ± 1 . 4)%, where the first uncertainty is statistical and the second systematic. The \( {A}_{\mathrm{T}}^{\mathrm{Re}} \) observable, which is related to the lepton forward-backward asymmetry, is measured to be \( {A}_{\mathrm{T}}^{\mathrm{Re}} \) = - 0 . 06 ± 0 . 08 ± 0 . 02. The \( {A}_{\mathrm{T}}^{(2)} \) and \( {A}_{\mathrm{T}}^{\mathrm{Im}} \) transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be \( {A}_{\mathrm{T}}^{(2)} \) = 0 . 11 ± 0 . 10 ± 0 . 02 and \( {A}_{\mathrm{T}}^{\mathrm{Im}} \) = 0 . 02 ± 0 . 10 ± 0 . 01. The results are consistent with Standard Model predictions and provide the world’s best constraint on the b → sγ photon polarisation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on K(V5S8)2 by Materials Project

K(V5S8)2 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted q6 geometry to ten S2- atoms. There are a spread of K–S bond distances ranging from 3.16–3.32 Å. In the second K1+ site, K1+ is bonded in a distorted q6 geometry to ten S2- atoms. There are a spread of K–S bond distances ranging from 3.16–3.32 Å. There are twelve inequivalent V+3.10+ sites. In the first V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.54 Å. In the second V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–54°. There are a spread of V–S bond distances ranging from 2.27–2.51 Å. In the third V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.53 Å. In the fourth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–54°. There are a spread of V–S bond distances ranging from 2.27–2.51 Å. In the fifth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of V–S bond distances ranging from 2.25–2.61 Å. In the sixth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.61 Å. In the seventh V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of V–S bond distances ranging from 2.25–2.61 Å. In the eighth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.61 Å. In the ninth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.45 Å. In the tenth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.45 Å. In the eleventh V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.46 Å. In the twelfth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.45 Å. There are sixteen inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and four V+3.10+ atoms. In the second S2- site, S2- is bonded to four V+3.10+ atoms to form distorted edge-sharing SV4 trigonal pyramids. In the third S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fourth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fifth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the sixth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the seventh S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the eighth S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the ninth S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the tenth S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the eleventh S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the twelfth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the thirteenth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fourteenth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fifteenth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and four V+3.10+ atoms. In the sixteenth S2- site, S2- is bonded to four V+3.10+ atoms to form distorted edge-sharing SV4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(SnAu2)2 by Materials Project

KAu4Sn2 crystallizes in the tetragonal I-4c2 space group. The structure is three-dimensional. K is bonded in a 8-coordinate geometry to eight equivalent Au atoms. There are four shorter (3.46 Å) and four longer (3.57 Å) K–Au bond lengths. Au is bonded in a 10-coordinate geometry to two equivalent K, four equivalent Au, and four equivalent Sn atoms. There are a spread of Au–Au bond distances ranging from 2.80–3.08 Å. There are a spread of Au–Sn bond distances ranging from 2.82–3.04 Å. Sn is bonded in a 8-coordinate geometry to eight equivalent Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoO2)4 by Materials Project

K(MoO2)4 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.08–3.25 Å. In the second K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.03–3.27 Å. There are four inequivalent Mo+3.75+ sites. In the first Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Mo–O bond distances ranging from 2.12–2.18 Å. In the second Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–53°. There are a spread of Mo–O bond distances ranging from 2.03–2.17 Å. In the third Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–56°. There are a spread of Mo–O bond distances ranging from 1.99–2.16 Å. In the fourth Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Mo–O bond distances ranging from 1.97–2.16 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.75+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(GeSe2)2 by Materials Project

K(GeSe2)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.38–3.95 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.37–3.98 Å. There are four inequivalent Ge+3.50+ sites. In the first Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form a mixture of corner and edge-sharing GeSe4 tetrahedra. There are a spread of Ge–Se bond distances ranging from 2.38–2.47 Å. In the second Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form corner-sharing GeSe4 tetrahedra. There are a spread of Ge–Se bond distances ranging from 2.35–2.47 Å. In the third Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form a mixture of corner and edge-sharing GeSe4 tetrahedra. There are a spread of Ge–Se bond distances ranging from 2.40–2.46 Å. In the fourth Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form corner-sharing GeSe4 tetrahedra. There are two shorter (2.63 Å) and two longer (2.64 Å) Ge–Se bond lengths. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 2-coordinate geometry to one K1+ and two Ge+3.50+ atoms. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to two K1+ and two Ge+3.50+ atoms. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to two K1+ and two Ge+3.50+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to three K1+ and two Ge+3.50+ atoms. In the fifth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two Ge+3.50+ atoms. In the sixth Se2- site, Se2- is bonded in a 3-coordinate geometry to one K1+ and two Ge+3.50+ atoms. In the seventh Se2- site, Se2- is bonded in a 2-coordinate geometry to three equivalent K1+ and two Ge+3.50+ atoms. In the eighth Se2- site, Se2- is bonded in a 2-coordinate geometry to one K1+ and two Ge+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoO2)4 by Materials Project

K(MoO2)4 crystallizes in the tetragonal P4/n space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (3.01 Å) and four longer (3.16 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (3.08 Å) and four longer (3.12 Å) K–O bond lengths. There are two inequivalent Mo+3.75+ sites. In the first Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–55°. There are a spread of Mo–O bond distances ranging from 2.07–2.15 Å. In the second Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–53°. There are a spread of Mo–O bond distances ranging from 2.00–2.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.75+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(FeS)2 by Materials Project

KFe2S2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded in a body-centered cubic geometry to eight equivalent S atoms. All K–S bond lengths are 3.31 Å. Fe is bonded to four equivalent S atoms to form a mixture of edge and corner-sharing FeS4 tetrahedra. All Fe–S bond lengths are 2.19 Å. S is bonded in a 8-coordinate geometry to four equivalent K and four equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(CrS2)2 by Materials Project

K(CrS2)2 crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one K(CrS2)2 sheet oriented in the (0, 0, 1) direction. K1+ is bonded in a 6-coordinate geometry to six equivalent S2- atoms. All K–S bond lengths are 3.09 Å. Cr+3.50+ is bonded to six S2- atoms to form edge-sharing CrS6 octahedra. There are three shorter (2.35 Å) and three longer (2.46 Å) Cr–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr+3.50+ atoms. In the second S2- site, S2- is bonded to three equivalent K1+ and three equivalent Cr+3.50+ atoms to form a mixture of distorted edge, face, and corner-sharing SK3Cr3 octahedra. The corner-sharing octahedral tilt angles are 39°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(WO3)3 by Materials Project

K(WO3)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share edges with twelve WO6 octahedra and faces with two equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.23–3.48 Å. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share edges with twelve WO6 octahedra and faces with two equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.22–3.48 Å. There are six inequivalent W+5.67+ sites. In the first W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–32°. There are a spread of W–O bond distances ranging from 1.93–2.00 Å. In the second W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–33°. There are a spread of W–O bond distances ranging from 1.90–1.97 Å. In the third W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–32°. There are a spread of W–O bond distances ranging from 1.92–1.96 Å. In the fourth W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–33°. There are a spread of W–O bond distances ranging from 1.92–1.96 Å. In the fifth W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–33°. There are a spread of W–O bond distances ranging from 1.94–2.01 Å. In the sixth W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–32°. There are a spread of W–O bond distances ranging from 1.90–1.97 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the tenth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the fourteenth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the seventeenth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the eighteenth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms.

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