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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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

Materials Data on K2Cu(IF)2 by Materials Project

K2Cu(IF)2 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. K1+ is bonded in a distorted square co-planar geometry to two equivalent I1- and four equivalent F1- atoms. Both K–I bond lengths are 3.76 Å. All K–F bond lengths are 2.65 Å. Cu2+ is bonded in a square co-planar geometry to four equivalent I1- atoms. All Cu–I bond lengths are 2.65 Å. I1- is bonded in a distorted square co-planar geometry to two equivalent K1+ and two equivalent Cu2+ atoms. F1- is bonded in a square co-planar geometry to four equivalent K1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(SiO2)3 by Materials Project

Na(SiO2)3 crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Na is bonded in a distorted hexagonal planar geometry to three equivalent O atoms. All Na–O bond lengths are 2.24 Å. Si is bonded to four O atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. There are three inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two equivalent Si atoms. In the second O site, O is bonded in a linear geometry to two equivalent Si atoms. In the third O site, O is bonded in a distorted trigonal planar geometry to one Na and two equivalent Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Nanometer flat blazed x-ray gratings using ion beam figure correction

With the development of nanometer accuracy stitching interferometry, ion beam figuring (IBF) of x-ray mirrors can now be achieved with unprecedented performance. However, the process of producing x-ray diffraction gratings on these surfaces may degrade the figure quality due to process errors introduced during the ruling of the grating grooves. To address this challenge, we have investigated the post-production correction of gratings using IBF, where stitching interferometry is used to provide in-process feedback. A concern with ion beam correction in this case is that ions will induce enough surface mobility of atoms to cause smoothing of the grating structure and degradation of diffraction efficiency. In this study we found however that it is possible to achieve a nanometer-level planarity of the global grating surface with IBF, while preserving the grating structure. The preservation was so good, that we could not detect a change in the diffraction efficiency after ion beam correction. This is of major importance in achieving ultra-high spectral resolution, and the preservation of brightness for coherent x-ray beams.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiSbP2O7 by Materials Project

LiSbP2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Li1+ is bonded in a distorted trigonal planar geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.89–2.62 Å. Sb3+ is bonded to six O2- atoms to form distorted SbO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Sb–O bond distances ranging from 2.15–2.52 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent SbO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 30–68°. There are a spread of P–O bond distances ranging from 1.53–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent SbO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–67°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Sb3+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Sb3+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Sb3+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaSn5S11 by Materials Project

CaSn5S11 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ca2+ is bonded in a distorted pentagonal planar geometry to five S2- atoms. There are a spread of Ca–S bond distances ranging from 2.81–3.24 Å. There are five inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing SnS6 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Sn–S bond distances ranging from 2.50–2.65 Å. In the second Sn4+ site, Sn4+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing SnS6 octahedra. The corner-sharing octahedra tilt angles range from 19–59°. There are a spread of Sn–S bond distances ranging from 2.56–2.68 Å. In the third Sn4+ site, Sn4+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing SnS6 octahedra. The corner-sharing octahedra tilt angles range from 4–59°. There are a spread of Sn–S bond distances ranging from 2.47–2.77 Å. In the fourth Sn4+ site, Sn4+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing SnS6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of Sn–S bond distances ranging from 2.52–2.67 Å. In the fifth Sn4+ site, Sn4+ is bonded to six S2- atoms to form a mixture of distorted edge and corner-sharing SnS6 octahedra. The corner-sharing octahedra tilt angles range from 4–42°. There are a spread of Sn–S bond distances ranging from 2.49–2.92 Å. There are eleven inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal planar geometry to three Sn4+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to one Ca2+ and two Sn4+ atoms. In the third S2- site, S2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Sn4+ atoms. In the fourth S2- site, S2- is bonded in a distorted T-shaped geometry to three Sn4+ atoms. In the fifth S2- site, S2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sn4+ atoms. In the sixth S2- site, S2- is bonded in a distorted trigonal pyramidal geometry to one Ca2+ and three Sn4+ atoms. In the seventh S2- site, S2- is bonded in a distorted T-shaped geometry to one Ca2+ and two Sn4+ atoms. In the eighth S2- site, S2- is bonded in a distorted T-shaped geometry to three Sn4+ atoms. In the ninth S2- site, S2- is bonded in a distorted trigonal planar geometry to three Sn4+ atoms. In the tenth S2- site, S2- is bonded in a T-shaped geometry to three Sn4+ atoms. In the eleventh S2- site, S2- is bonded in a distorted trigonal planar geometry to three Sn4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pt3O4 by Materials Project

Pt3O4 crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Pt+2.67+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.00 Å. O2- is bonded in a trigonal planar geometry to three equivalent Pt+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3O4 by Materials Project

Cu3O4 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Cu+2.67+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.88 Å. O2- is bonded in a trigonal planar geometry to three equivalent Cu+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Planar Defect Layers Template a High-Pressure InBi Polymorph

The short- and long-range order of III–V materials under high pressure has long been the subject of debate, with advancements in structural characterization leading to significant revisions to the accepted structural models. Despite these revisions, previous high-pressure structural assignments in the In–Bi system include the site-disordered β-Sn structure type, a structure type demonstrated to be nonexistent in analogous III–V systems. While X-ray diffraction is consistent with site disordering in InBi at high pressure, cluster expansion calculations indicate that disordering requires temperatures above 3000 K. Here, we propose InBi as a model material for studying unique high-pressure planar defects due to its highly anisotropic stress-dependent properties and structure. Specifically, we identify two sets of planar defects that mimic the diffraction pattern of a site disordered β-Sn structure type and are compatible with the calculated disorder barrier. We derive these defects by symmetry relations over crystallographic transitions. Density functional theory calculations of the proposed defects suggest that these defects are stabilized by diminishing interlayer separations with pressure. Further, we find that one of the proposed defects closely resembles a bulk high-pressure phase of InBi, InBi-ϵ, and we assert that the proposed defects order upon heating, acting as a template for InBi-ϵ growth. The proposed defects and their electronic structure provide a basis for the trend of superconducting critical temperature with increasing pressure. These methods for identifying defects are generalizable to other materials with reports of site disorder at high pressure, prompting a broader search for related high-pressure defects.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Pressure-induced cation and vacancy disorder-order transition and near-zero τ f in deficient hexagonal perovskite Ba 8 ZnTa 6 O 24 dielectrics

Pressure applications can enable the tuning of atomic/defect ordering and provide access to new functional materials. Here, in this study, we report that pressure-induced structural transformation featuring disorder-order transition of both cations and vacancies in the 8-layer deficient hexagonal perovskite tantalate dielectrics Ba 8 ZnTa 6 O 24 , which transformed the structure from twin to shift and remarkably lowered the temperature coefficient of resonant frequency τ f down to near zero (∼0.56 ppm/°C) from 38 ppm/°C for the twinned precursor. The atomic scale STEM-HAADF and EDS results confirm the ordering of Zn in the Ta host at the nanometer scale in the shifted material featuring well-ordered Ba 8 ZnTa 6 O 24 slabs intergrown with Ba 3 ZnTa 2 O 9 and Ba 5 Ta 4 O 15 monolayers and anti-phase grain boundaries as planar defects. The pressure-induced twin-shift structural transformation of Ba 8 ZnTa 6 O 24 features the rare constant concentration of the hexagonal stacked layers, which is allowed by the vacancy ordering at the central layers of face-shared octahedral (FSO) trimers avoiding the FSO B-B repulsion, and remarkably the faster cationic ordering kinetics compared with the 2:1 ordered complex perovskites. Although the inclusion of numerous planar defects and the oxidizable atomic defects led to significant p-type conduction and inhomogeneous electrical microstructures, resulting in an extraordinarily high extrinsic dielectric loss for the high-pressure shifted Ba 8 ZnTa 6 O 24 pellet, the intrinsically near-zero τ f could make the shifted Ba 8 ZnTa 6 O 24 perovskite an ideal microwave dielectric resonator candidate if the defects could be eliminated.

high pressure↗
DOE OSTI2020

Materials Data on ZrBeSi by Materials Project

ZrBeSi crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Be2+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Be–Si bond lengths are 2.16 Å. Zr2+ is bonded to six equivalent Si4- atoms to form a mixture of corner, edge, and face-sharing ZrSi6 octahedra. The corner-sharing octahedral tilt angles are 45°. All Zr–Si bond lengths are 2.82 Å. Si4- is bonded in a distorted trigonal planar geometry to three equivalent Be2+ and six equivalent Zr2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC2N by Materials Project

BC2N crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. B3+ is bonded in a trigonal planar geometry to two equivalent C and one N3- atom. Both B–C bond lengths are 1.60 Å. The B–N bond length is 1.42 Å. C is bonded to one B3+, two equivalent C, and one N3- atom to form distorted corner-sharing CBC2N tetrahedra. There is one shorter (1.57 Å) and one longer (1.60 Å) C–C bond length. The C–N bond length is 1.47 Å. N3- is bonded in a trigonal planar geometry to one B3+ and two equivalent C atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Hexaazatriphenylene‐Based Two‐Dimensional Conductive Covalent Organic Framework with Anisotropic Charge Transfer

Abstract The development of covalent organic frameworks (COFs) with efficient charge transport is of immense interest for applications in optoelectronic devices. To enhance COF charge transport properties, electroactive building blocks and dopants can be used to induce extended conduction channels. However, understanding their intricate interplay remains challenging. We designed and synthesized a tailor‐made COF structure with electroactive hexaazatriphenylene (HAT) core units and planar dioxin (D) linkages, denoted as HD‐COF. With the support of theoretical calculations, we found that the HAT units in the HD‐COF induce strong, eclipsed π–π stacking. The unique stacking of HAT units and the weak in‐plane conjugation of dioxin linkages leads to efficient anisotropic charge transport. We fabricated HD‐COF films to minimize the grain boundary effect of bulk COFs, which resulted in enhanced conductivity. As a result, the HD‐COF films showed an electrical conductivity as high as 1.25 S cm −1 after doping with tris(4‐bromophenyl)ammoniumyl hexachloroantimonate.

Kim, Seong‐Wook↗
DOE OSTI2023

Hexaazatriphenylene‐Based Two‐Dimensional Conductive Covalent Organic Framework with Anisotropic Charge Transfer

Here, the development of covalent organic frameworks (COFs) with efficient charge transport is of immense interest for applications in optoelectronic devices. To enhance COF charge transport properties, electroactive building blocks and dopants can be used to induce extended conduction channels. However, understanding their intricate interplay remains challenging. We designed and synthesized a tailor-made COF structure with electroactive hexaazatriphenylene (HAT) core units and planar dioxin (D) linkages, denoted as HD-COF. With the support of theoretical calculations, we found that the HAT units in the HD-COF induce strong, eclipsed π–π stacking. The unique stacking of HAT units and the weak in-plane conjugation of dioxin linkages leads to efficient anisotropic charge transport. We fabricated HD-COF films to minimize the grain boundary effect of bulk COFs, which resulted in enhanced conductivity. As a result, the HD-COF films showed an electrical conductivity as high as 1.25 S cm −1 after doping with tris(4-bromophenyl)ammoniumyl hexachloroantimonate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Crystal structure of oxibendazole, C 12 H 15 N 3 O 3

The crystal structure of oxibendazole has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Oxibendazole crystallizes in space group C2/c (#15) with a = 23.18673(22), b = 5.35136(5), c = 19.88932(13) Å, β = 97.0876(9)°, V = 2449.018(17) Å 3 , and Z = 8. The structure consists of hydrogen-bonded layers of planar molecules parallel to the bc-plane. Strong N–H∙∙∙N hydrogen bonds link the molecules into dimers, with a graph set R2,2(8). N–H∙∙∙O hydrogen bonds further link these dimers into layers parallel to the bc-plane. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

36 MATERIALS SCIENCE↗
DOE OSTI2022

Humble planar defects in SiGe nanopillars

We report a {001} planar defect found in SiGe nanopillars. The defect structure, determined by atomic-resolution electron microscopy, matches the Humble defect model proposed for diamond. We also investigate several possible variants of the Humble structure using first-principles calculations and find that the one lowest in energy is in agreement with the scanning transmission electron microscope images. The pillar composition has been analyzed with electron energy loss spectroscopy, which hints at how the defect is formed. Our results show that the structure and formation process of defects in nanostructured group IV semiconductors can be different from their bulk counterparts.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Two-Frequency RF Fields Induced Multipactor in Coaxial Transmission Lines

Multipactor is a nonlinear discharge phenomenon that occurs in vacuum RF systems, potentially leading to signal distortion, power loss, and even permanent damage to high-power components. This study presents a detailed investigation of two-surface multipactor in coaxial transmission lines under two-frequency excitation, using one-dimensional (1D) Monte Carlo simulations validated by three-dimensional (3D) Particle-in-Cell (PIC) results and experimental data. Introducing a second carrier mode is shown to suppress multipactor by reshaping and shrinking the susceptibility region, with the extent and location of suppression strongly dependent on the device aspect ratio and the relative phase of the second mode. Distinct suppression patterns emerge across different frequency–gap distance (fd) regimes, and in certain cases, susceptibility expansion is also observed. The study identifies and distinguishes pure and mixed multipactor modes in coaxial geometry, where analytical mode boundaries are not readily defined. Unlike planar systems, pure-mode regions in coaxial structures overlap with mixed-mode domains, complicating classification. Image charge forces are found to have minimal effect on susceptibility thresholds but do influence electron growth rates. These findings provide new insights into waveform-driven control of multipactor in high-power RF systems.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Materials Data on PdPbF4 by Materials Project

PdPbF4 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Pd2+ is bonded in a square co-planar geometry to four equivalent F1- atoms. All Pd–F bond lengths are 2.02 Å. Pb2+ is bonded in a 8-coordinate geometry to eight equivalent F1- atoms. All Pb–F bond lengths are 2.58 Å. F1- is bonded in a distorted trigonal planar geometry to one Pd2+ and two equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rh3Cl4 by Materials Project

Rh3Cl4 crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Rh is bonded in a square co-planar geometry to four equivalent Cl atoms. All Rh–Cl bond lengths are 2.33 Å. Cl is bonded in a trigonal planar geometry to three equivalent Rh atoms.

36 MATERIALS SCIENCE↗