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DOE OSTI2020

Materials Data on KMg6Zr by Materials Project

KMg6Zr crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent ZrMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Zr2 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Mg8Zr2 cuboctahedra, and faces with four equivalent ZrMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.34–3.55 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Zr atoms to form distorted MgK2Mg8Zr2 cuboctahedra that share corners with twelve equivalent MgK2Mg8Zr2 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent ZrMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent ZrMg12 cuboctahedra, and faces with six equivalent MgK2Mg8Zr2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.30–3.37 Å. There are one shorter (3.32 Å) and one longer (3.36 Å) Mg–Zr bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Zr atoms. There are one shorter (2.99 Å) and one longer (3.02 Å) Mg–Mg bond lengths. Both Mg–Zr bond lengths are 3.17 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Zr atoms. Both Mg–Zr bond lengths are 3.18 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Zr atoms. Both Mg–Zr bond lengths are 3.16 Å. Zr is bonded to twelve Mg atoms to form ZrMg12 cuboctahedra that share corners with four equivalent ZrMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Zr2 cuboctahedra, faces with two equivalent ZrMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Mg8Zr2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KMg6Ti by Materials Project

KMg6Ti crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent TiMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Ti2 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Mg8Ti2 cuboctahedra, and faces with four equivalent TiMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.35–3.50 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Ti atoms to form distorted MgK2Mg8Ti2 cuboctahedra that share corners with twelve equivalent MgK2Mg8Ti2 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent TiMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent TiMg12 cuboctahedra, and faces with six equivalent MgK2Mg8Ti2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.27–3.30 Å. There are one shorter (3.34 Å) and one longer (3.37 Å) Mg–Ti bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Ti atoms. There are one shorter (2.97 Å) and one longer (2.98 Å) Mg–Mg bond lengths. Both Mg–Ti bond lengths are 3.08 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Ti atoms. Both Mg–Ti bond lengths are 3.10 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Ti atoms. Both Mg–Ti bond lengths are 3.10 Å. Ti is bonded to twelve Mg atoms to form TiMg12 cuboctahedra that share corners with four equivalent TiMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Ti2 cuboctahedra, faces with two equivalent TiMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Mg8Ti2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KMg6Nb by Materials Project

KMg6Nb crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent NbMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Mg8Nb2 cuboctahedra, and faces with four equivalent NbMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.27–3.50 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Nb atoms to form distorted MgK2Mg8Nb2 cuboctahedra that share corners with twelve equivalent MgK2Mg8Nb2 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent NbMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent NbMg12 cuboctahedra, and faces with six equivalent MgK2Mg8Nb2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.23–3.30 Å. There are one shorter (3.25 Å) and one longer (3.31 Å) Mg–Nb bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. There are one shorter (2.87 Å) and one longer (2.90 Å) Mg–Mg bond lengths. Both Mg–Nb bond lengths are 3.06 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. Both Mg–Nb bond lengths are 3.07 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. Both Mg–Nb bond lengths are 3.09 Å. Nb is bonded to twelve Mg atoms to form NbMg12 cuboctahedra that share corners with four equivalent NbMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent NbMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Mg8Nb2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KMg6W by Materials Project

KMg6W crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent WMg12 cuboctahedra, edges with eight equivalent MgK2Mg8W2 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Mg8W2 cuboctahedra, and faces with four equivalent WMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.27–3.44 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent W atoms to form distorted MgK2Mg8W2 cuboctahedra that share corners with twelve equivalent MgK2Mg8W2 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent WMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent WMg12 cuboctahedra, and faces with six equivalent MgK2Mg8W2 cuboctahedra. There are two shorter (3.20 Å) and six longer (3.21 Å) Mg–Mg bond lengths. There are one shorter (3.26 Å) and one longer (3.29 Å) Mg–W bond lengths. In the second Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent K, six Mg, and two equivalent W atoms. Both Mg–Mg bond lengths are 2.82 Å. Both Mg–W bond lengths are 2.95 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent K, six Mg, and two equivalent W atoms. Both Mg–W bond lengths are 2.98 Å. In the fourth Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent K, six Mg, and two equivalent W atoms. Both Mg–W bond lengths are 2.97 Å. W is bonded to twelve Mg atoms to form WMg12 cuboctahedra that share corners with four equivalent WMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Mg8W2 cuboctahedra, faces with two equivalent WMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Mg8W2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHfMg6 by Materials Project

KMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with eight equivalent MgK2Hf2Mg8 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Hf2Mg8 cuboctahedra, and faces with four equivalent HfMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.33–3.54 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Hf atoms to form distorted MgK2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgK2Hf2Mg8 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with six equivalent MgK2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.28–3.37 Å. There are one shorter (3.31 Å) and one longer (3.35 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. There are one shorter (2.98 Å) and one longer (3.01 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.16 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.13 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.16 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Hf2Mg8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3GeSe3 by Materials Project

K3GeSe3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Se2- atoms to form a mixture of distorted corner, edge, and face-sharing KSe6 octahedra. The corner-sharing octahedral tilt angles are 39°. There are a spread of K–Se bond distances ranging from 3.36–3.70 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of K–Se bond distances ranging from 3.45–3.54 Å. In the third K1+ site, K1+ is bonded to six Se2- atoms to form a mixture of distorted corner, edge, and face-sharing KSe6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 33–68°. There are a spread of K–Se bond distances ranging from 3.29–3.54 Å. Ge3+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are two shorter (2.39 Å) and one longer (2.40 Å) Ge–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to six K1+ and one Ge3+ atom. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to six K1+ and one Ge3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K4Sb2O5 by Materials Project

K4Sb2O5 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are one shorter (2.72 Å) and four longer (2.82 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a 4-coordinate geometry to six O2- atoms. There are four shorter (2.82 Å) and two longer (3.36 Å) K–O bond lengths. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are two shorter (2.71 Å) and four longer (2.93 Å) K–O bond lengths. In the fourth K1+ site, K1+ is bonded to six O2- atoms to form distorted KO6 pentagonal pyramids that share corners with two equivalent SbO4 tetrahedra and edges with two equivalent KO6 pentagonal pyramids. There are two shorter (2.70 Å) and four longer (2.91 Å) K–O bond lengths. There are two inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded to four O2- atoms to form SbO4 tetrahedra that share corners with two equivalent KO6 pentagonal pyramids and corners with two equivalent SbO4 tetrahedra. There are two shorter (1.93 Å) and two longer (2.09 Å) Sb–O bond lengths. In the second Sb3+ site, Sb3+ is bonded in a water-like geometry to two equivalent O2- atoms. Both Sb–O bond lengths are 1.95 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to five K1+ and one Sb3+ atom to form a mixture of distorted edge, face, and corner-sharing OK5Sb octahedra. The corner-sharing octahedra tilt angles range from 42–65°. In the second O2- site, O2- is bonded to five K1+ and one Sb3+ atom to form a mixture of distorted edge, face, and corner-sharing OK5Sb octahedra. The corner-sharing octahedra tilt angles range from 42–65°. In the third O2- site, O2- is bonded in a 3-coordinate geometry to three K1+ and two equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1993

An experimental investigation of high temperature superconducting microstrip antennas at K- and Ka-band frequencies

The recent discovery of high temperature superconductors (HTS) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS results in narrow bandwidths and high patch edge impedances of such antennas. To investigate the performance of superconducting microstrip antennas, three antenna architectures at K and Ka-band frequencies are examined. Superconducting microstrip antennas that are directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line were designed and fabricated on lanthanum aluminate substrates using YBa2Cu3O7 superconducting thin films. For each architecture, a single patch antenna and a four element array were fabricated. Measurements from these antennas, including input impedance, bandwidth, patterns, efficiency, and gain are presented. The measured results show usable antennas can be constructed using any of the architectures. All architectures show excellent gain characteristics, with less than 2 dB of total loss in the four element arrays. Although the direct and gap coupled antennas are the simplest antennas to design and fabricate, they suffer from narrow bandwidths. The electromagnetically coupled antenna, on the other hand, allows the flexibility of using a low permittivity substrate for the patch radiator, while using HTS for the feed network, thus increasing the bandwidth while effectively utilizing the low loss properties of HTS. Each antenna investigated in this research is the first of its kind reported.

Richard, Mark A.↗
DOE OSTI2020

Materials Data on K2SnSe3 by Materials Project

K2SnSe3 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 to six Se2- atoms to form KSe6 octahedra that share corners with two equivalent KSe6 octahedra, corners with three equivalent SnSe4 tetrahedra, edges with three equivalent KSe6 octahedra, and edges with two equivalent SnSe4 tetrahedra. The corner-sharing octahedral tilt angles are 8°. There are a spread of K–Se bond distances ranging from 3.41–3.58 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of K–Se bond distances ranging from 3.44–3.66 Å. Sn4+ is bonded to four Se2- atoms to form SnSe4 tetrahedra that share corners with three equivalent KSe6 octahedra, edges with two equivalent KSe6 octahedra, and an edgeedge with one SnSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 22–88°. There are a spread of Sn–Se bond distances ranging from 2.50–2.65 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to five K1+ and one Sn4+ atom to form a mixture of distorted corner and edge-sharing SeK5Sn octahedra. The corner-sharing octahedra tilt angles range from 2–60°. In the second Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to two K1+ and two equivalent Sn4+ atoms. In the third Se2- site, Se2- is bonded to five K1+ and one Sn4+ atom to form a mixture of corner and edge-sharing SeK5Sn octahedra. The corner-sharing octahedra tilt angles range from 2–60°.

36 MATERIALS SCIENCE↗
NASA NTRS1978

Photoabsorption cross sections of methane and ethane, 1380-1600 A, at T equals 295 K and T equals 200 K

Photoabsorption cross sections of methane and ethane have been determined in the wavelength range from 1380 to 1600 A at room (295 K) and dry-ice (200 K) temperatures. It is found that the room-temperature ethane data are in excellent agreement with the older measurements of Okabe and Becker (1963) rather than with more recent determinations and that a small systematic blueshift occurs at the foot of the molecular absorption edges of both gases as the gases are cooled from room temperature to 200 K, a value close to the actual temperature of the Jovian atmosphere. It is concluded that methane photoabsorption will dominate until its cross section is about 0.01 that of ethane, which occurs at about 1440 A, and that ethane should be the dominant photoabsorber in the Jovian atmosphere in the region from above 1440 A to not farther than 1575 A.

Mount, G. H.↗
DOE OSTI2020

Materials Data on K3(FeS2)2 by Materials Project

K3Fe2S4 crystallizes in the orthorhombic Pnma 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 six S2- atoms. There are a spread of K–S bond distances ranging from 3.13–3.59 Å. In the second K1+ site, K1+ is bonded to six S2- atoms to form distorted KS6 octahedra that share corners with eight equivalent FeS4 tetrahedra, edges with two equivalent FeS4 tetrahedra, and faces with two equivalent KS6 octahedra. There are a spread of K–S bond distances ranging from 3.12–3.32 Å. Fe+2.50+ is bonded to four S2- atoms to form FeS4 tetrahedra that share corners with four equivalent KS6 octahedra, an edgeedge with one KS6 octahedra, and edges with two equivalent FeS4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–64°. There are a spread of Fe–S bond distances ranging from 2.26–2.31 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to four equivalent K1+ and two equivalent Fe+2.50+ atoms. In the second S2- site, S2- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Fe+2.50+ atoms. In the third S2- site, S2- is bonded in a 6-coordinate geometry to four K1+ and two equivalent Fe+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K6Sn3As5 by Materials Project

K6Sn3As5 crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. there are five inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to five As3- atoms to form distorted KAs5 trigonal bipyramids that share a cornercorner with one SnAs4 tetrahedra, corners with four equivalent KAs5 trigonal bipyramids, an edgeedge with one SnAs4 tetrahedra, and edges with three equivalent KAs5 trigonal bipyramids. There are a spread of K–As bond distances ranging from 3.39–3.67 Å. In the second K1+ site, K1+ is bonded in a 5-coordinate geometry to five As3- atoms. There are a spread of K–As bond distances ranging from 3.53–3.77 Å. In the third K1+ site, K1+ is bonded in a 5-coordinate geometry to five As3- atoms. There are a spread of K–As bond distances ranging from 3.34–3.73 Å. In the fourth K1+ site, K1+ is bonded in a square co-planar geometry to four As3- atoms. There are a spread of K–As bond distances ranging from 3.46–3.64 Å. In the fifth K1+ site, K1+ is bonded in a 4-coordinate geometry to four equivalent As3- atoms. All K–As bond lengths are 3.59 Å. There are three inequivalent Sn3+ sites. In the first Sn3+ site, Sn3+ is bonded in a trigonal non-coplanar geometry to three As3- atoms. There are two shorter (2.69 Å) and one longer (2.71 Å) Sn–As bond lengths. In the second Sn3+ site, Sn3+ is bonded in a trigonal non-coplanar geometry to three As3- atoms. There are two shorter (2.74 Å) and one longer (2.77 Å) Sn–As bond lengths. In the third Sn3+ site, Sn3+ is bonded to four As3- atoms to form SnAs4 tetrahedra that share corners with two equivalent KAs5 trigonal bipyramids, an edgeedge with one SnAs4 tetrahedra, and edges with two equivalent KAs5 trigonal bipyramids. There are two shorter (2.64 Å) and two longer (2.71 Å) Sn–As bond lengths. There are five inequivalent As3- sites. In the first As3- site, As3- is bonded in a 8-coordinate geometry to six K1+ and two Sn3+ atoms. In the second As3- site, As3- is bonded in a 8-coordinate geometry to six K1+ and two Sn3+ atoms. In the third As3- site, As3- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Sn3+ atoms. In the fourth As3- site, As3- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Sn3+ atoms. In the fifth As3- site, As3- is bonded in a 9-coordinate geometry to seven K1+ and two equivalent Sn3+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Edge Based Viscous Method for Node-Centered Formulations

This paper presents a novel, efficient, conservative, edge-based method for evaluation of mean flow viscous fluxes and turbulence-model diffusion terms of the Reynolds-averaged Navier-Stokes equations on tetrahedral grids. The new method is implemented in a practical, node-centered, finite-volume computational fluid dynamics solver. The baseline finite-volume scheme that is equivalent to a second-order accurate finite-element Galerkin approximation of viscous stresses is reformulated. The order of operations to compute the cell-based Green-Gauss gradients is changed to combine the operations by edge, which leads to an equivalent formulation on tetrahedral grids, improves efficiency, and preserves the compact discretization stencil based on the nearest neighbors. The computational results presented in this paper verify the implementation of this edge-based method by comparing its accuracy and iterative convergence with those of the well verified and validated baseline formulation. Efficiency gains for residual and Jacobian evaluations result in significant reduction of time to solution. This novel edge-based formulation on tetrahedra can be seamlessly combined with the baseline formulation on cells of other types for computing solutions on mixed-element grids.

Edge Based↗
DOE OSTI2020

Materials Data on K2SnBi by Materials Project

K2SnBi crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 6-coordinate geometry to four equivalent Sn and four equivalent Bi atoms. There are two shorter (3.88 Å) and two longer (4.09 Å) K–Sn bond lengths. There are a spread of K–Bi bond distances ranging from 3.62–3.90 Å. In the second K site, K is bonded in a 2-coordinate geometry to four equivalent Sn and four equivalent Bi atoms. There are two shorter (3.95 Å) and two longer (4.05 Å) K–Sn bond lengths. There are a spread of K–Bi bond distances ranging from 3.66–3.89 Å. Sn is bonded to eight K, two equivalent Sn, and two equivalent Bi atoms to form a mixture of distorted corner, edge, and face-sharing SnK8Sn2Bi2 cuboctahedra. Both Sn–Sn bond lengths are 3.32 Å. Both Sn–Bi bond lengths are 3.08 Å. Bi is bonded in a 10-coordinate geometry to eight K and two equivalent Sn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KCrS2 by Materials Project

KCrS2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to six equivalent S2- atoms. All K–S bond lengths are 3.13 Å. Cr3+ is bonded to six equivalent S2- atoms to form edge-sharing CrS6 octahedra. All Cr–S bond lengths are 2.46 Å. S2- is bonded to three equivalent K1+ and three equivalent Cr3+ atoms to form a mixture of distorted corner and edge-sharing SK3Cr3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Novel internal measurements of ion cyclotron frequency range fast-ion driven modes

Abstract Novel internal measurements and analysis of ion cyclotron frequency range fast-ion driven modes in DIII-D are presented. Observations, including internal density fluctuation ( n ~ ) measurements obtained via Doppler backscattering, are presented for modes at low harmonics of the ion cyclotron frequency localized in the edge. The measurements indicate that these waves, identified as coherent ion cyclotron emission (ICE), have high wave number, k ⊥ ρ fast ≳ 1, consistent with the cyclotron harmonic wave branch of the magnetoacoustic cyclotron instability, or electrostatic instability mechanisms. Measurements show extended spatial structure (at least ∼1/6 the minor radius). These edge ICE modes undergo amplitude modulation correlated with edge localized modes (ELM) that is qualitatively consistent with expectations for ELM-induced fast-ion transport.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗