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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K(IO3)2 by Materials Project

K(O3I)2 crystallizes in the orthorhombic Fdd2 space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.70–3.17 Å. In the second K site, K is bonded in a body-centered cubic geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.87–3.07 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one I atom. The O–I bond length is 1.81 Å. In the second O site, O is bonded in a 1-coordinate geometry to one K and two I atoms. There are one shorter (1.88 Å) and one longer (2.38 Å) O–I bond lengths. In the third O site, O is bonded in a 1-coordinate geometry to one K and one I atom. The O–I bond length is 1.83 Å. In the fourth O site, O is bonded in a 4-coordinate geometry to two equivalent K and two I atoms. There are one shorter (1.85 Å) and one longer (2.61 Å) O–I bond lengths. In the fifth O site, O is bonded in a 4-coordinate geometry to two K and two I atoms. There are one shorter (1.84 Å) and one longer (2.68 Å) O–I bond lengths. In the sixth O site, O is bonded in a 1-coordinate geometry to two equivalent K and one I atom. The O–I bond length is 1.83 Å. In the seventh O site, O is bonded in a distorted single-bond geometry to one K and one I atom. The O–I bond length is 1.91 Å. In the eighth O site, O is bonded in a 1-coordinate geometry to one K and one I atom. The O–I bond length is 1.89 Å. In the ninth O site, O is bonded in a 4-coordinate geometry to two K and two I atoms. There are one shorter (1.85 Å) and one longer (2.63 Å) O–I bond lengths. There are three inequivalent I sites. In the first I site, I is bonded in a 5-coordinate geometry to three O atoms. In the second I site, I is bonded in a 6-coordinate geometry to five O atoms. In the third I site, I is bonded in a 3-coordinate geometry to five O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(TeO3)2 by Materials Project

K(TeO3)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.94–3.16 Å. In the second K site, K is bonded in a 1-coordinate geometry to three O atoms. There are one shorter (2.54 Å) and two longer (2.91 Å) K–O bond lengths. There are five inequivalent Te sites. In the first Te site, Te is bonded to six O atoms to form corner-sharing TeO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There is two shorter (1.83 Å) and four longer (2.05 Å) Te–O bond length. In the second Te site, Te is bonded to five O atoms to form corner-sharing TeO5 square pyramids. The corner-sharing octahedra tilt angles range from 40–62°. There are a spread of Te–O bond distances ranging from 1.96–2.28 Å. In the third Te site, Te is bonded to six O atoms to form TeO6 octahedra that share corners with four equivalent TeO6 octahedra and corners with two equivalent TeO5 square pyramids. The corner-sharing octahedral tilt angles are 46°. All Te–O bond lengths are 1.95 Å. In the fourth Te site, Te is bonded to six O atoms to form TeO6 octahedra that share corners with four TeO6 octahedra and corners with two equivalent TeO5 square pyramids. The corner-sharing octahedra tilt angles range from 45–48°. There are a spread of Te–O bond distances ranging from 1.94–1.99 Å. In the fifth Te site, Te is bonded to six O atoms to form TeO6 octahedra that share corners with four TeO6 octahedra and corners with two equivalent TeO5 square pyramids. The corner-sharing octahedra tilt angles range from 41–46°. There are a spread of Te–O bond distances ranging from 1.90–2.01 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two Te atoms. In the second O site, O is bonded in a 2-coordinate geometry to one K and two Te atoms. In the third O site, O is bonded in a bent 150 degrees geometry to one K and one Te atom. In the fourth O site, O is bonded in a 2-coordinate geometry to one K and two equivalent Te atoms. In the fifth O site, O is bonded in a distorted bent 150 degrees geometry to two equivalent Te atoms. In the sixth O site, O is bonded in a distorted trigonal planar geometry to one K and two Te atoms. In the seventh O site, O is bonded in a 4-coordinate geometry to two K and two Te atoms. In the eighth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two Te atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

K in an Urban World: New Contexts for Hydraulic Conductivity

Abstract Hydraulic conductivity ( K ) is a key hydrologic parameter widely recognized to be difficult to estimate and constrain, with little consistent assessment in disturbed, urbanized soils. To estimate K , it is either measured, or simulated by pedotransfer functions, which relate K to easily measured soil properties. We measured K in urbanized soils by double‐ring infiltrometer ( K dring ), near‐saturated tension infiltrometry ( K minidisk ), and constant head borehole permeametry ( K borehole ), along with other soil properties across the major soil orders in 12 United States cities. We compared measured K with that predicted from the pedotransfer function, ROSETTA. We found that regardless of soil texture, K dring was consistently larger than K minidisk ; with the latter having slightly less sample variance. K borehole was dependent upon specific subsurface conditions, and contrary to common expectations, did not always decrease with depth. Based on either soil textural class, or percent textural separates (sand, silt clay), ROSETTA did not accurately predict measured K for surface nor subsurface soils. We go on to discuss how K varies in urban landscapes, the role of measurement methods and artifacts in the perception of this metric, and implications for hydrologic modeling. Overall, we aim to inspire consistency and coherence when addressing K ‐related challenges in sustainable urban water management.

Shuster, W. D.↗
DOE OSTI2021

Structure Tuning, Strong Second Harmonic Generation Response, and High Optical Stability of the Polar Semiconductors Na 1- x K x AsQ 2

We report the mixed cation compounds Na 1-x K x AsSe 2 (x = 0.8, 0.65, 0.5) and Na 0.1 K 0.9 AsS 2 crystallize in the polar noncentrosymmetric space group Cc. The AAsQ(2) (A = alkali metals, Q = S, Se) family features one-dimensional (1D) 1 / ∞ [AQ 2 - ] chains comprising corner-sharing pyramidal AQ 3 units in which the packing of these chains is dependent on the alkali metals. The parallel 1 / ∞ [AQ(2) - ] chains interact via short As ∙∙∙Se contacts, which increase in length when the fraction of K atoms is increased. The increase in the As ∙∙∙Se interchain distance increases the band gap from 1.75 eV in γ-NaAsSe 2 to 2.01 eV in Na 0.35 K 0.65 AsSe 2 , 2.07 eV in Na 0.2 K 0.8 AsSe 2 , and 2.18 eV in Na 0.1 K 0.9 AsS 2 . The Na 1-x K x AsSe 2 (x = 0.8, 0.65) compounds melt congruently at approximately 316 °C. Wavelength-dependent second harmonic generation (SHG) measurements on powder samples of Na 1-x K x AsSe 2 (x = 0.8, 0.65, 0.5) and Na 0.1 K 0.9 AsS 2 suggest that Na 0.2 K 0.8 AsSe 2 and Na 0.1 K 0.9 AsS 2 have the highest SHG response and exhibit significantly higher laser-induced damage thresholds (LIDTs). Theoretical SHG calculations on Na 0.5 K 0.5 AsSe 2 confirm its SHG response with the highest value of d 33 = 22.5 pm/V χ 333 (2) = 45.0 pm/V). The effective nonlinearity for a randomly oriented powder is calculated to be d eff = 18.9 pm/V χ eff (2) = 37.8 pm/V), which is consistent with the experimentally obtained value of d eff = 16.5 pm/V χ eff (2) = 33.0 pm/V). Three-photon absorption is the dominant mechanism for the optical breakdown of the compounds under intense excitation at 1580 nm, with Na 0.2 K 0.8 AsSe 2 exhibiting the highest stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Measurement of K*(892) ± production in inelastic pp collisions at the LHC

The first results on K*(892) ± resonance production in inelastic pp collisions at LHC energies of √s = 5.02, 8, and 13 TeV are presented. The K*(892) ± has been reconstructed via its hadronic decay channel K*(892)→±K$^0_S$ +π ± with the ALICE detector. Measurements of transverse momentum distributions, p T -integrated yields, and mean transverse momenta for charged K*(892) are found to be consistent with previous ALICE measurements for neutral K*(892) within uncertainties. For p T >1 GeV/c the K*(892) ± transverse momentum spectra become harder with increasing centre-of-mass energy from 5.02 to 13 TeV, similar to what previously observed for charged kaons and pions. For p T < GeV/c the K*(892) ± yield does not evolve significantly and the abundance of K*(892) ± relative to K is rather independent of the collision energy. The transverse momentum spectra, measured for K*(892) ± at midrapidity in the interval 0 < p T <15 GeV/c, are not well described by predictions of different versions of PYTHIA 6, PYTHIA 8 and EPOS-LHC event generators. These generators reproduce the measured p T -integrated K *± /K ratios and describe well the momentum dependence for p T <2 GeV/c.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Constraining the $\overline{K}$N coupled channel dynamics using femtoscopic correlations at the LHC

The interaction of K – with protons is characterised by the presence of several coupled channels, systems like $\overline{K}$ 0 n and πΣ with a similar mass and the same quantum numbers as the K – p state. The strengths of these couplings to the K – p system are of crucial importance for the understanding of the nature of the Λ(1405) resonance and of the attractive K – p strong interaction. In this article, we present measurements of the K – p correlation functions in relative momentum space obtained in pp collisions at $\sqrt{s}$=13 Te, in p–Pb collisions at $\sqrt{s_{NN}}$= 5.02 Te, and (semi)peripheral Pb–Pb collisions at $\sqrt{s_{NN}}$= 5.02 Te. The emitting source size, composed of a core radius anchored to the K + p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the $\overline{K}$ 0 n and πΣ inelastic channels on the measured K – p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights ω, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured K – p interaction indicates that, while the πΣ –K – p dynamics is well reproduced by the model, the coupling to the $\overline{K}$ 0 n channel in the model is currently underestimated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Materials Data on K by Materials Project

K is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded to twelve K atoms to form a mixture of corner, edge, and face-sharing KK12 cuboctahedra. There are six shorter (4.69 Å) and six longer (4.71 Å) K–K bond lengths. In the second K site, K is bonded to twelve K atoms to form a mixture of corner, edge, and face-sharing KK12 cuboctahedra. All K–K bond lengths are 4.71 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 10-coordinate geometry to ten K atoms. There are a spread of K–K bond distances ranging from 4.54–4.72 Å. In the second K site, K is bonded in a 11-coordinate geometry to eleven K atoms. There are a spread of K–K bond distances ranging from 4.57–4.65 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight K atoms. There are a spread of K–K bond distances ranging from 4.48–4.78 Å. In the second K site, K is bonded in a 8-coordinate geometry to eight K atoms. Both K–K bond lengths are 4.54 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded to twelve equivalent K atoms to form a mixture of face and edge-sharing KK12 cuboctahedra. All K–K bond lengths are 4.68 Å. In the second K site, K is bonded in a 6-coordinate geometry to six K atoms. Both K–K bond lengths are 4.18 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K is beta structured and crystallizes in the cubic P4_132 space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 2-coordinate geometry to two equivalent K atoms. Both K–K bond lengths are 4.64 Å. In the second K site, K is bonded in a 12-coordinate geometry to six K atoms. All K–K bond lengths are 4.29 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight K atoms. There are a spread of K–K bond distances ranging from 4.54–4.66 Å. In the second K site, K is bonded in a 8-coordinate geometry to eight K atoms. Both K–K bond lengths are 4.54 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight equivalent K atoms. All K–K bond lengths are 4.61 Å. In the second K site, K is bonded to seven K atoms to form a mixture of distorted corner, edge, and face-sharing KK7 pentagonal bipyramids. There are four shorter (4.29 Å) and one longer (4.46 Å) K–K bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K by Materials Project

K crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded to eight equivalent K atoms to form distorted edge-sharing KK8 hexagonal bipyramids. All K–K bond lengths are 4.51 Å. In the second K site, K is bonded in a distorted hexagonal planar geometry to six K atoms. There are a spread of K–K bond distances ranging from 4.28–4.46 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Impact of K-Optimization on Trap Concentration in (Ag,Cu)(In,Ga)Se 2 Solar Cells

Recent progress has been made in improving efficiency in Cu(In,Ga)Se 2 (CIGS) absorbers with steady increases in peak efficiency. One way this has been achieved is by adding Ag to CIGS (ACIGS) to achieve higher V OC . However, these efficiencies are still well below the Shockley-Queisser efficiency limit, and traps acting as recombination centers and compensating centers are one thing limiting the solar efficiency. Past research in CIGS has shown that alkali treatment can improve the efficiency and metastability problems in CIGS, but less is understood about the role of alkali treatments in ACIGS. Here, we investigate the impact of potassium in ACIGS through its impact on trap incorporation and minority carrier lifetime. The samples in this study were grown in a roll-to-roll coater with Mo, ACIGS, CdS, and ZnO structure. Both cells were grown identically except the second (K-optimized) cell was grown with increased K-doping of the Mo contact and was more Cu-poor near the surface to optimize the K profile. This resulted in an efficiency increase from 16.8% to 18.7% for the K-optimized cell, which was mostly due to a 65 mV V OC increase. The doping profile showed a 2X increase in acceptor concentration of the K-optimized cell (2.5×10 15 cm -3 ) which suggests that the K was better incorporated into the ACIGS after these optimizations. To characterize the traps in these cells, deep level transient and optical spectroscopy were used. The DLOS measurements showed an EV+0.98 eV trap whose concentration was reduced 10X in the K-optimized cell (4×10 14 cm -3 ). This is consistent with previous results from the alkali treatment in CIGS, which also showed a decrease in near-conduction band trap concentration [1], but the reduction was larger than previous studies possibly indicating the combination of K and Cu-poor surface may both have aided in reducing the EV+0.98 eV trap concentration. The other primary trap is the mid-gap trap (EV+0.58 eV), which was quantified using DLTS. Its concentration decreased from 9×10 13 cm -3 to 4×10 13 cm -3 in the K-optimized sample, which is a 2X reduction. Previous studies have shown this trap is likely an efficient recombination center [2], which makes sense because it is near mid-gap. This trap has also been associated with V OC instability and reduction, so reducing this trap concentration is essential to achieve high V OC and cell efficiency. To help confirm this association, time-resolved photoluminescence measurements have shown in this sample set and a previous study that the minority carrier lifetime (19 ns baseline to 56 ns K-optimized) and this EV+0.56 eV trap concentration are inversely proportional, which would be expected for a recombination-limited carrier lifetime. The K optimization of ACIGS results in significantly improved cell efficiency and reduced trap concentrations that correlate with the improved material and electrical properties. We will report on this and the impact of the K optimization on the cell metastability.

14 SOLAR ENERGY↗
DOE OSTI2020

Materials Data on K(IO3)3 by Materials Project

K(O3I)3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.82–3.25 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to one K and one I atom. The O–I bond length is 1.87 Å. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one K and one I atom. The O–I bond length is 1.85 Å. In the third O site, O is bonded in a distorted single-bond geometry to one K and one I atom. The O–I bond length is 1.87 Å. In the fourth O site, O is bonded in a distorted single-bond geometry to one K and one I atom. The O–I bond length is 1.85 Å. In the fifth O site, O is bonded in a distorted trigonal planar geometry to one K and two I atoms. There are one shorter (1.85 Å) and one longer (2.41 Å) O–I bond lengths. In the sixth O site, O is bonded in a 1-coordinate geometry to one K and two I atoms. There are one shorter (1.87 Å) and one longer (2.61 Å) O–I bond lengths. In the seventh O site, O is bonded in a 1-coordinate geometry to one K and one I atom. The O–I bond length is 1.82 Å. In the eighth O site, O is bonded in a 1-coordinate geometry to one K and two I atoms. There are one shorter (1.84 Å) and one longer (2.60 Å) O–I bond lengths. In the ninth O site, O is bonded in a distorted single-bond geometry to two I atoms. There are one shorter (1.87 Å) and one longer (2.64 Å) O–I bond lengths. There are three inequivalent I sites. In the first I site, I is bonded in a distorted octahedral geometry to six O atoms. In the second I site, I is bonded in a 5-coordinate geometry to three O atoms. In the third I site, I is bonded in a 6-coordinate geometry to four O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Multiplicity dependence of K*(892) ± production in pp collisions at $\sqrt{s}$ = 13 TeV

The first results of K*(892) ± production at midrapidity (|y| < 0.5) in pp collisions at $\sqrt{s}$= 13 TeV as a function of the event multiplicity are presented. The K*(892) ± has been reconstructed via its hadronic decay channel K*(892) ± → π ± + K$^0_{\textrm{S}}$ using the ALICE detector at the LHC. For each multiplicity class, the differential transverse momentum (p T ) spectrum, the mean transverse momentum ⟨p T ⟩, the p T -integrated yield (dN/dy), and the ratio of the K*(892) ± to K$^0_{\textrm{S}}$ yields are reported. These are consistent with previous K*(892) 0 resonance results with a higher level of precision. Comparisons with phenomenological models such as PYTHIA6, PYTHIA8, EPOS-LHC, and DIPSY are also discussed. For the first time, a significant K*(892) ± /K$^0_{\textrm{S}}$ suppression in pp collisions is observed at a 7σ level passing from low to high multiplicity events. The ratios of the p T -differential yields of K*(892) ± and K$^0_{\textrm{S}}$ in high and low multiplicity events are also presented along with their double ratio. For p T ≲ 2 GeV/c this double ratio persists below unity by more than 3σ suggesting that the suppression affects mainly low p T resonances. The measured decreasing trend of the K*(892) ± /K$^0_{\textrm{S}}$ ratio with increasing multiplicity, which in heavy-ion collisions is typically attributed to the rescattering of decay particles of the short-lived resonances, is reproduced by the EPOS-LHC model without the use of hadronic afterburners.

Hadronic resonance production↗
DOE OSTI2024

K ∗ (892) ± resonance production in Pb−Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

The production of K *⁢(892) ± meson resonance is measured at midrapidity (| y |<0.5) in Pb-Pb collisions at $\sqrt{^sNN}$ = 5.02 TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel K *⁢(892) ± → K $^0_S$⁢π ± . The transverse momentum distributions are obtained for various centrality intervals in the p T range of 0.4-16 GeV/ c . Measurements of integrated yields, mean transverse momenta, and particle yield ratios are reported and found to be consistent with previous ALICE measurements for K *⁢(892) 0 within uncertainties. The p T -integrated yield ratio 2 K *⁢(892) ± ⁢/(⁢ K + + K - ) in central Pb-Pb collisions shows a significant suppression at a level of 9.3σ⁢ relative to pp collisions. Thermal model calculations result in an overprediction of the particle yield ratio. Although both hadron resonance gas in partial chemical equilibrium (HRG-PCE) and MUSIC + SMASH simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas MUSIC + SMASH simulations tend to overpredict the particle yield ratio. These observations, along with the kinetic freeze-out temperatures extracted from the yields measured for light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which decreases with increasing collision centrality percentile. The p T-differential yield ratios 2 K *⁢(892) ±⁢ /(⁢ K + + K - ) and 2 K *⁢(892) ± ⁢/(⁢π + +π - ) are presented and compared with measurements in pp collisions at $\sqrt{s}$ = 5.02 TeV. Both particle ratios are found to be suppressed by up to a factor of five at p T <2.0 GeV/ c in central Pb-Pb collisions and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor ( R AA ) shows a smooth evolution with centrality and is found to be below unity at p T >8 GeV/ c , consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗