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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on NaNbWO6 by Materials Project

NaNbWO6 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Na1+ is bonded in a hexagonal planar geometry to six O2- atoms. There are two shorter (2.64 Å) and four longer (2.69 Å) Na–O bond lengths. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 39–44°. All Nb–O bond lengths are 2.00 Å. W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with two equivalent WO6 octahedra and corners with four equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 35–39°. There is four shorter (1.93 Å) and two longer (1.95 Å) W–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Nb5+, and one W6+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent W6+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Nb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaTaWO6 by Materials Project

NaTaWO6 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Na1+ is bonded in a hexagonal planar geometry to six O2- atoms. There are two shorter (2.65 Å) and four longer (2.67 Å) Na–O bond lengths. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra and corners with four equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 39–43°. There is two shorter (1.98 Å) and four longer (1.99 Å) Ta–O bond length. W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with two equivalent WO6 octahedra and corners with four equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–39°. There is four shorter (1.93 Å) and two longer (1.95 Å) W–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ta5+, and one W6+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent W6+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiNbWO6 by Materials Project

LiNbWO6 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Li1+ is bonded in a hexagonal planar geometry to six O2- atoms. There are two shorter (2.59 Å) and four longer (2.65 Å) Li–O bond lengths. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 40–48°. There are four shorter (2.00 Å) and two longer (2.01 Å) Nb–O bond lengths. W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with two equivalent WO6 octahedra and corners with four equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 35–40°. There is four shorter (1.93 Å) and two longer (1.95 Å) W–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Nb5+, and one W6+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent W6+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Li1+ and two equivalent Nb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmAl3Pd2 by Materials Project

SmPd2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Sm is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All Sm–Pd bond lengths are 3.15 Å. Pd is bonded in a 9-coordinate geometry to three equivalent Sm and six equivalent Al atoms. All Pd–Al bond lengths are 2.64 Å. Al is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdAl3Pd2 by Materials Project

GdPd2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Gd is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All Gd–Pd bond lengths are 3.14 Å. Pd is bonded in a 9-coordinate geometry to three equivalent Gd and six equivalent Al atoms. All Pd–Al bond lengths are 2.63 Å. Al is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UAl3Ni2 by Materials Project

UNi2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. U is bonded in a distorted hexagonal planar geometry to six equivalent Ni atoms. All U–Ni bond lengths are 2.97 Å. Ni is bonded in a 12-coordinate geometry to three equivalent U and six equivalent Al atoms. All Ni–Al bond lengths are 2.50 Å. Al is bonded in a 12-coordinate geometry to four equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UAl3Pd2 by Materials Project

UPd2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. U is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All U–Pd bond lengths are 3.11 Å. Pd is bonded in a 9-coordinate geometry to three equivalent U and six equivalent Al atoms. All Pd–Al bond lengths are 2.63 Å. Al is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbAu3Se2 by Materials Project

RbAu3Se2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Rb1+ is bonded in a distorted hexagonal planar geometry to six equivalent Se2- atoms. All Rb–Se bond lengths are 3.80 Å. Au1+ is bonded in a distorted linear geometry to two equivalent Se2- atoms. Both Au–Se bond lengths are 2.48 Å. Se2- is bonded in a 6-coordinate geometry to three equivalent Rb1+ and three equivalent Au1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuAl3Pd2 by Materials Project

PuPd2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Pu is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All Pu–Pd bond lengths are 3.15 Å. Pd is bonded in a 9-coordinate geometry to three equivalent Pu and six equivalent Al atoms. All Pd–Al bond lengths are 2.62 Å. Al is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpAl3Pd2 by Materials Project

NpPd2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Np is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All Np–Pd bond lengths are 3.16 Å. Pd is bonded in a 9-coordinate geometry to three equivalent Np and six equivalent Al atoms. All Pd–Al bond lengths are 2.62 Å. Al is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaAlSiO4 by Materials Project

NaAlSiO4 crystallizes in the trigonal R3c space group. The structure is three-dimensional. Na1+ is bonded in a hexagonal planar geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.46–2.85 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four equivalent SiO4 tetrahedra. There is two shorter (1.74 Å) and two longer (1.75 Å) Al–O bond length. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four equivalent AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.64 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Na1+, one Al3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Na1+, one Al3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+, one Al3+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiSbWO6 by Materials Project

LiSbWO6 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Li1+ is bonded in a hexagonal planar geometry to six O2- atoms. There are two shorter (2.53 Å) and four longer (2.58 Å) Li–O bond lengths. W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with two equivalent WO6 octahedra and corners with four equivalent SbO6 octahedra. The corner-sharing octahedra tilt angles range from 34–43°. There is four shorter (1.93 Å) and two longer (1.94 Å) W–O bond length. Sb5+ is bonded to six O2- atoms to form SbO6 octahedra that share corners with two equivalent SbO6 octahedra and corners with four equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 43–52°. There is four shorter (1.99 Å) and two longer (2.00 Å) Sb–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one W6+, and one Sb5+ atom. In the second O2- site, O2- is bonded to two equivalent Li1+ and two equivalent Sb5+ atoms to form distorted corner-sharing OLi2Sb2 tetrahedra. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent W6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Planar Self-similar Antennas for Broadband Millimeter-Wave Measurements

Self-similar antennas offer extremely broadband functionality and easily scalable designs. Self-similar designs with a four-arm layout are also suited for dual polarization through excitations of opposing arms, although there has only been limited use of them for millimeter-wave detectors. These antennas have been used for measurements of the cosmic microwave background (CMB), which encompass a wide frequency range and are now actively focusing more on polarization anisotropies. Here, we analyze multiple planar self-similar antenna designs with simulations in high-frequency structure simulator and ongoing physical testing. They all exhibit broadband operation between 130 and 230 GHz and can couple to both linear polarizations through the previously mentioned four-arm symmetry. Furthermore, simulations include each antenna design coupled to an extended hemispherical, AR-coated lenslet. From these, a basic bowtie-like arm design produced minimal polarization wobble with moderate beam efficiency, while a hybrid trapezoidal design provided high beam efficiency with small polarization wobble. Current fabrication versions of each are being tested, coupled to multichroic microwave kinetic inductance detectors. These planar self-similar antennas, when implemented in CMB and other detectors, could improve observations while simultaneously simplifying fabrication and detector layout.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Materials Data on MoPt3 by Materials Project

Pt3Mo1 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Mo6+ is bonded in a hexagonal planar geometry to six equivalent Pt2- atoms. All Mo–Pt bond lengths are 2.74 Å. There are four inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded to three equivalent Mo6+ and nine Pt2- atoms to form a mixture of face, edge, and corner-sharing PtMo3Pt9 cuboctahedra. There are six shorter (2.80 Å) and three longer (2.89 Å) Pt–Pt bond lengths. In the second Pt2- site, Pt2- is bonded to twelve Pt2- atoms to form PtPt12 cuboctahedra that share corners with six equivalent PtPt12 cuboctahedra, edges with eighteen PtMo3Pt9 cuboctahedra, and faces with eighteen PtMo3Pt9 cuboctahedra. All Pt–Pt bond lengths are 2.80 Å. In the third Pt2- site, Pt2- is bonded to three equivalent Mo6+ and nine Pt2- atoms to form a mixture of face, edge, and corner-sharing PtMo3Pt9 cuboctahedra. All Pt–Mo bond lengths are 2.74 Å. There are six shorter (2.80 Å) and three longer (2.89 Å) Pt–Pt bond lengths. In the fourth Pt2- site, Pt2- is bonded to sixteen Pt2- atoms to form a mixture of face, edge, and corner-sharing PtPt16 cuboctahedra. There are a spread of Pt–Pt bond distances ranging from 2.80–5.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi5BO10 by Materials Project

BBi5O10 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.37–1.40 Å. There are five inequivalent Bi+3.40+ sites. In the first Bi+3.40+ site, Bi+3.40+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing BiO6 pentagonal pyramids. There are a spread of Bi–O bond distances ranging from 2.15–2.68 Å. In the second Bi+3.40+ site, Bi+3.40+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.12–2.44 Å. In the third Bi+3.40+ site, Bi+3.40+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing BiO6 pentagonal pyramids. There are a spread of Bi–O bond distances ranging from 2.23–2.57 Å. In the fourth Bi+3.40+ site, Bi+3.40+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.17–2.83 Å. In the fifth Bi+3.40+ site, Bi+3.40+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.21–2.99 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Bi+3.40+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Bi+3.40+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Bi+3.40+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi+3.40+ atoms. In the fifth O2- site, O2- is bonded to four Bi+3.40+ atoms to form distorted edge-sharing OBi4 tetrahedra. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one B3+ and two Bi+3.40+ atoms. In the seventh O2- site, O2- is bonded in a single-bond geometry to one B3+ and one Bi+3.40+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to one B3+ and two Bi+3.40+ atoms. In the ninth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Bi+3.40+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to four Bi+3.40+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Toward a Theory of the Evolution of Drop Morphology and Splintering by Freezing

Abstract The drop freezing process is described by a phase-field model. Two cases are considered: when the freezing is triggered by central nucleation and when nucleation occurs on the drop surface. Depending on the environmental temperature and drop size, different morphological structures develop. Detailed dendritic growth was simulated at the first stage of drop freezing. Independent of the nucleation location, a decrease in temperature within the range from ~−5° to −25°C led to an increase in the number of dendrites and a decrease in their width and the interdendritic space. At temperatures lower than about −25°C, a planar front developed following surface nucleation, while dendrites formed a granular-like structure with small interdendritic distances following bulk nucleation. An ice shell grew in at the same time (but slower) as dendrites following surface nucleation, while it started forming once the dendrites have reached the drop surface in the case of central nucleation. The formed ice morphology at the first freezing stage predefined the splintering probability. We assume that stresses needed to break the ice shell arose from freezing of the water in the interdendritic spaces. Under this assumption, the number of possible splinters/fragments was proportional to the number of dendrites, and the maximum rate of splintering/fragmentation occurred within a temperature range of about −10° to −20°C, is in agreement with available laboratory and in situ measurements. At temperatures < −25°C, freezing did not lead to the formation of significant stresses, making splintering unlikely. The number of dendrites increased with drop size, causing a corresponding increase in the number of splinters. Examples of morphology that favors drop cracking are presented, and the duration of the freezing stages is evaluated. Sensitivity of the freezing process to the surface fluxes is discussed.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Materials Data on CeZn3Pd2 by Materials Project

CePd2Zn3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Ce is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All Ce–Pd bond lengths are 3.08 Å. Pd is bonded in a 12-coordinate geometry to three equivalent Ce and six equivalent Zn atoms. All Pd–Zn bond lengths are 2.68 Å. Zn is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeAl3Pd2 by Materials Project

CePd2Al3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Ce is bonded in a distorted hexagonal planar geometry to six equivalent Pd atoms. All Ce–Pd bond lengths are 3.14 Å. Pd is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Al atoms. All Pd–Al bond lengths are 2.65 Å. Al is bonded in a 12-coordinate geometry to four equivalent Pd atoms.

36 MATERIALS SCIENCE↗