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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Cs2Lu7CCl18 by Materials Project

Cs2Lu7CCl18 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Cs is bonded to twelve Cl atoms to form CsCl12 cuboctahedra that share corners with nine LuCl6 octahedra, edges with three equivalent CsCl12 cuboctahedra, edges with three equivalent LuCCl5 octahedra, and faces with three equivalent LuCCl5 octahedra. The corner-sharing octahedra tilt angles range from 45–48°. There are a spread of Cs–Cl bond distances ranging from 3.73–3.87 Å. There are two inequivalent Lu sites. In the first Lu site, Lu is bonded to one C and five Cl atoms to form LuCCl5 octahedra that share corners with two equivalent CsCl12 cuboctahedra, corners with two LuCl6 octahedra, an edgeedge with one CsCl12 cuboctahedra, edges with four equivalent LuCCl5 octahedra, and a faceface with one CsCl12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–45°. The Lu–C bond length is 2.49 Å. There are a spread of Lu–Cl bond distances ranging from 2.59–2.73 Å. In the second Lu site, Lu is bonded to six equivalent Cl atoms to form LuCl6 octahedra that share corners with six equivalent CsCl12 cuboctahedra and corners with six equivalent LuCCl5 octahedra. The corner-sharing octahedral tilt angles are 45°. All Lu–Cl bond lengths are 2.62 Å. C is bonded in an octahedral geometry to six equivalent Lu atoms. There are three inequivalent Cl sites. In the first Cl site, Cl is bonded in a distorted L-shaped geometry to two equivalent Cs and two equivalent Lu atoms. In the second Cl site, Cl is bonded in a distorted L-shaped geometry to one Cs and two equivalent Lu atoms. In the third Cl site, Cl is bonded in a 2-coordinate geometry to one Cs and two Lu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMg6Ga by Materials Project

CsMg6Ga crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded in a 10-coordinate geometry to twelve Mg and two equivalent Ga atoms. There are a spread of Cs–Mg bond distances ranging from 3.58–4.11 Å. Both Cs–Ga bond lengths are 3.72 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Cs, five Mg, and two equivalent Ga atoms. There are a spread of Mg–Mg bond distances ranging from 3.26–3.45 Å. Both Mg–Ga bond lengths are 2.92 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Cs and eight Mg atoms. There are two shorter (3.06 Å) and four longer (3.11 Å) Mg–Mg bond lengths. In the third Mg site, Mg is bonded in a 1-coordinate geometry to two equivalent Cs, five Mg, and one Ga atom. The Mg–Mg bond length is 2.89 Å. The Mg–Ga bond length is 2.96 Å. In the fourth Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Cs and six Mg atoms. Ga is bonded in a 8-coordinate geometry to two equivalent Cs and six Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs2Al(TeO4)3 by Materials Project

Cs2Al(TeO4)3 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Cs is bonded to six O atoms to form distorted CsO6 octahedra that share corners with three equivalent AlO6 octahedra and corners with nine equivalent TeO6 octahedra. The corner-sharing octahedra tilt angles range from 66–72°. There are three shorter (3.09 Å) and three longer (3.12 Å) Cs–O bond lengths. Al is bonded to six equivalent O atoms to form AlO6 octahedra that share corners with six equivalent CsO6 octahedra and corners with six equivalent TeO6 octahedra. The corner-sharing octahedra tilt angles range from 42–66°. All Al–O bond lengths are 1.91 Å. Te is bonded to six O atoms to form TeO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four equivalent TeO6 octahedra, and corners with six equivalent CsO6 octahedra. The corner-sharing octahedra tilt angles range from 42–72°. There is two shorter (1.90 Å) and four longer (1.99 Å) Te–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Cs, one Al, and one Te atom. In the second O site, O is bonded in a 2-coordinate geometry to one Cs and two equivalent Te atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Mixed-Valent Copper Chalcogenides: Tuning Structures and Electronic Properties Using Multiple Anions

A series of mixed-anion copper chalcogenides have been prepared using solid-state methods including ACu 4.2 TeS 2 (A = K, Rb, Cs), which adopt the KCu 4 S 3 structure type. The mixedanion motif has an expanded sublattice, relative to KCu 4 S 3 , that can accommodate additional Cu atoms at its interstitial sites that are unoccupied in the parent structure. The variable temperature transport shows that the materials are p-type metals with carrier densities on the order of 10 21 cm -3 and room-temperature electrical conductivity as high as 4000 S cm -1 . Band structures calculated using density functional theory corroborate the experimental data and indicate that the interstitial Cu atoms lower the carrier concentration and increase the Fermi level of the materials. The layered structure has Te and S atoms occupying unique sites within the ACu 4.2 TeS 2 structure, where relatively hard S 2- anions prefer Wyckoff positions where they can form energetically favorable acid-base interactions with hard alkali cations. The phenomenon is observed in the related K 3 Cu 8 Te 2 S 4 system, which also has a fully ordered layered structure. Here, we believe that the report provides new chemical guidelines for targeting ordered multianion structures, as well as a unique method for tuning the electronic properties of metallic chalcogenides.

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

Selective heterogeneous capture and release of actinides using carborane-functionalized electrodes

Here we report the heterogenization of molecular, electrochemically switchable ortho-substituted carboranes ( PO Cb, PO Cb-Pyr) for selective metal capture. Films of PO Cb and PO Cb-Pyr on glassy carbon and carbon fiber (CF) electrodes demonstrated heterogeneous electrochemical behaviour that was enhanced by the inclusion of single-walled carbon nanotubes (CNTs). Galvanostatically charged CF|CNT| PO Cb and CF|CNT| PO Cb-Pyr electrodes selectively captured and released actinides (Th 4+ , UO 2 2+ ) from mixed solutions containing alkali (Cs + ), lanthanide (Nd 3+ , Sm 3+ ) and actinide (Th 4+ , UO 2 2+ ) metal ions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on CsCdI3O by Materials Project

CsCdOI3 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a distorted bent 120 degrees geometry to two O and one I atom. There are one shorter (2.93 Å) and one longer (3.15 Å) Cs–O bond lengths. The Cs–I bond length is 4.25 Å. In the second Cs site, Cs is bonded in a 2-coordinate geometry to two O and two equivalent I atoms. There are one shorter (3.08 Å) and one longer (3.22 Å) Cs–O bond lengths. There are one shorter (3.84 Å) and one longer (4.04 Å) Cs–I bond lengths. There are two inequivalent Cd sites. In the first Cd site, Cd is bonded to four I atoms to form corner-sharing CdI4 tetrahedra. There are a spread of Cd–I bond distances ranging from 2.80–2.90 Å. In the second Cd site, Cd is bonded to four I atoms to form corner-sharing CdI4 tetrahedra. There are a spread of Cd–I bond distances ranging from 2.77–2.91 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted trigonal non-coplanar geometry to two Cs and one I atom. The O–I bond length is 1.93 Å. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to two Cs and two I atoms. There are one shorter (2.62 Å) and one longer (2.67 Å) O–I bond lengths. There are six inequivalent I sites. In the first I site, I is bonded in a 2-coordinate geometry to one Cd and one O atom. In the second I site, I is bonded in a distorted bent 120 degrees geometry to one Cd and one O atom. In the third I site, I is bonded in a water-like geometry to two Cd atoms. In the fourth I site, I is bonded in a distorted L-shaped geometry to one Cs and two Cd atoms. In the fifth I site, I is bonded in a distorted water-like geometry to one Cd and one O atom. In the sixth I site, I is bonded in a 3-coordinate geometry to two equivalent Cs and one Cd atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

On the Use of Surfactant-Complexed Chitosan for Toughening 3D Printed Polymethacrylate Composites

This work reports a simple approach to prepare toughened 3D-printed polymethacrylate (PMA) composites using surfactant-modified chitosan (SMCS) particles at loadings between 2–10 wt%. Chitosan (CS) is modified with anionic surfactant, sodium dodecyl sulfate, via ionic complexation to facilitate compatibility and dispersion of CS to PMA matrix by non-covalent interactions between the components. The study successfully demonstrates high-accuracy 3D printing of composites with significant improvements in the overall mechanical properties. The composite with the best loading of 8 wt% SMCS shows a tensile modulus of 1.23 ± 0.05 GPa, a tensile strength at 49.8 ± 0.96 MPa, a yield stress at 33.3 ± 1.48 MPa, and a strain-at-ailure 10.3 ± 0.61%, which are 45%, 40%, 32%, and 68% higher than neat PMA, respectively. This provides a significant improvement in toughness at 4.92 ± 0.55 MJ m -3 for the composite, 184% higher than that of neat PMA. The marked increase in toughness is due to enhanced filler-matrix interactions which improve the ability of the 3D printed composite to absorb energy under tensile load. The results from this work provide new understandings into the strategies for design and preparation of stereolithography 3D printed materials reinforced with toughening fillers from renewable resources.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Interplay between Perovskite Magic-Sized Clusters and Amino Lead Halide Molecular Clusters

Recent progress has been made on the synthesis and characterization of metal halide perovskite magic-sized clusters (PMSCs) with ABX 3 composition ( A = C H 3 N H 3 + or Cs + , B = P b 2 + , and X = C l − , Br - , or I - ). However, their mechanism of growth and structure is still not well understood. In our effort to understand their structure and growth, we discovered that a new species can be formed without the CH 3 NH 3 + component, which we name as molecular clusters (MCs). Specifically, CH 3 NH 3 PbBr 3 PMSCs, with a characteristic absorption peak at 424 nm, are synthesized using PbBr 2 and CH 3 NH 3 Br as precursors and butylamine (BTYA) and valeric acid (VA) as ligands, while MCs, with an absorption peak at 402 nm, are synthesized using solely PbBr 2 and BTYA, without CH 3 NH 3 Br. Interestingly, PMSCs are converted spontaneously overtime into MCs. An isosbestic point in their electronic absorption spectra indicates a direct interplay between the PMSCs and MCs. Therefore, we suggest that the MCs are precursors to the PMSCs. From spectroscopic and extended X-ray absorption fine structure (EXAFS) results, we propose some tentative structural models for the MCs. The discovery of the MCs is critical to understanding the growth of PMSCs as well as larger perovskite quantum dots (PQDs) or nanocrystals (PNCs).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

Spectroscopic evidence for infall around an extraordinary IRAS source in Ophiuchus

Millimeter-wave continuum observations and spectral line observations of the J = 5-4 and J = 2-1 transitions of CS toward IRAS 16293-2422, an extremely cold infrared source associated with a high-velocity molecular outflow in the Rho Ophiuchi molecular cloud, are reported. The observations indicate that this source is a dust-enshrouded object embedded in a dense, elongated configuration of molecular gas whose major axis is roughly orthogonal to the direction of the double bipolar outflow observed in it. The observations appear to provide spectroscopic evidence for significant mass infall motions associated with a young stellar object, and suggest that IRAS 16293-2422 is a true protostar.

Walker, Christopher K.↗
NASA NTRS1991

An unbiased survey for dense cores in the Lynds 1630 molecular cloud

An unbiased, systematic survey for dense cores within the L1630 (Orion B) molecular cloud has been completed. This survey provides the first complete census of dense (n greater tha 10,000/cu cm) cores within a molecular cloud. To identify the dense gas, 3.6 square degrees of the L1630 cloud were surveyed in the J = 2-1 transition of CS. CS emission was detected over 10 percent of the area surveyed, and this emission is not uniformly distributed throughout the cloud but is confined to 42 dense cores. The size, shape, velocity dispersion, and mass of these cores are examined. Comparison of the mass contained within dense cores with the total gas mass within the surveyed region, estimated from CO emission, reveals that the dense cores constitute only a small fraction (not greater than 19 percent) of the total cloud mass.

Lada, Elizabeth A.↗
DOE OSTI2021

Composites and additive manufacturing for high-field coil supports for stellarators

The utilization of composites layered on an additive manufactured substrate, for the production of coil supports for modular coils in small or middle size experimental stellarators is assessed. The focus of the study is a monolithic coil support comprising the coils of a half-period of a stellarator, somewhat similar to the ones in UST_2 and ARIES-CS stellarators. However, the concept may be applicable to quasi-monolithic coil supports (coil forms of NCSX type) or individual coil casings (W7-X type).Coil supports for stellarators require high precision, stiffness and strength for large contorted parts. Traditionally, monolithic coil supports are produced by steel casting/forging and final machining. This production method and material gives accurate, stiff and strong coil supports, but the method may be expensive for monolithic supports due to the geometrical complexity and required accuracy of the structure. In relation to those matters, this work investigates whether a monolithic coil support comprising an additive manufactured resin substrate, which is externally (outward from the coils) surrounded with a thick layer of fibre-reinforced resin, may achieve enough strength and stiffness under middle/high magnetic fields. Finite element calculations are produced to obtain the direction of the principal stresses and their values in compression and tension at different areas of the monolithic support, which is relevant for anisotropic materials. The feasibility of directional application of (carbon) fibres on the winding surface of the stellarator outward from the coils is experimentally tested on a scaled-down additively manufactured prototype of a monolithic support. The strength and stiffness of the composite structure appears sufficient for common magnetic fields in experimental stellarators, and the 3D-composite design and manufacturing was technically feasible.

Queral, Vicente↗
DOE OSTI2022

Periodic Trends within Actinyl(VI) Nitrates and Their Structures, Vibrational Spectra, and Electronic Properties

In this work, a series of actinyl(VI) nitrate salts of the form MAnO 2 (NO 3 ) 3 , where M = NH 4 + K + , Rb + , Cs + , and Me 4 N + and AnO 2 2+ = U, Np, Pu, and AnO 2 (NO 3 ) 2 (H 2 O) 2 ·H 2 O, and the uranyl tetranitrates M 2 UO 2 (NO 3 ) 4 have been synthesized from aqueous solution and their structures determined using single-crystal X-ray diffraction. Together, these complexes represent an isostructural series of actinide complexes among the salts crystallized with the same charge-compensating cation and have been studied using vibrational spectroscopy including Raman and Fourier-transform infrared. Periodic trends in both the structural properties of these complexes and their vibrational spectra are presented and discussed, in particular the invariant nature of the O≡An≡O asymmetric stretching frequencies observed across the actinyl series. Electronic structure calculations were performed at a variety of levels of theory to aid in the interpretation of the vibrational data and to correlate trends in the data with the underlying electronic properties of these molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

The Role of Alkalis in Orchestrating Uranyl-Peroxide Reactivity Leading to Direct Air Capture of Carbon Dioxide

Spectator ions have known and emerging roles in aqueous metal-cation chemistry, respectively directing solubility, speciation, and reactivity. Here, in this work, we isolate and structurally characterize the last two metastable members of the alkali uranyl triperoxide series, the Rb + and Cs + salts (Cs-U 1 and Rb-U 1 ). We document their rapid solution polymerization via small-angle X-ray scattering, which is compared to the more stable Li + , Na + and K + analogues. To understand the role of the alkalis, we also quantify alkali-hydroxide promoted peroxide deprotonation and decomposition, which generally exhibits increasing reactivity with increasing alkali size. Cs-U 1 , the most unstable of the uranyl triperoxide monomers, undergoes ambient direct air capture of CO 2 in the solid-state, converting to Cs 4 [U VI O 2 (CO 3 ) 3 ], evidenced by single-crystal X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. We have attempted to benchmark the evolution of Cs-U 1 to uranyl tricarbonate, which involves a transient, unstable hygroscopic solid that contains predominantly pentavalent uranium, quantified by X-ray photoelectron spectroscopy. Powder X-ray diffraction suggests this intermediate state contains a hydrous derivative of CsU V O 3 , where the parent phase has been computationally predicted, but not yet synthesized.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on CsTl(SO5)2 by Materials Project

CsTl(SO5)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to twelve O atoms. There are a spread of Cs–O bond distances ranging from 3.24–3.73 Å. Tl is bonded to six O atoms to form TlO6 octahedra that share corners with four equivalent SO4 tetrahedra. There are a spread of Tl–O bond distances ranging from 2.23–2.33 Å. S is bonded to four O atoms to form SO4 tetrahedra that share corners with two equivalent TlO6 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of S–O bond distances ranging from 1.47–1.53 Å. There are five inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cs and one Tl atom. In the second O site, O is bonded in a single-bond geometry to two equivalent Cs and one S atom. In the third O site, O is bonded in a 2-coordinate geometry to one Cs, one Tl, and one S atom. In the fourth O site, O is bonded in a single-bond geometry to one Cs and one S atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one Cs, one Tl, and one S atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Structural Studies of Alloyed and Nanoparticle Transition Metal Dichalcogenides by Selenium-77 Solid-State Nuclear Magnetic Resonance Spectroscopy

Layered transition metal dichalcogenides (TMDCs) such as MoS 2 , MoSe 2 , and WSe 2 are under intense investigation because they are atomically thin semiconductors with photophysical properties that can be tuned by changing their composition or morphology. Mechanochemical processing has been proposed as a method to obtain alloyed TMDCs in the series Mo 1–x W x S y Se 2–y (x = 0–1; y = 0–2). However, elucidating the chemical transformations occurring at the atomic scale following mechanochemical processing can be challenging because the products are often amorphous or microcrystalline. To address this challenge, we probe TMDC mixing and alloying by using a combination of powder X-ray diffraction, Raman spectroscopy, diffuse reflectance spectroscopy, 77 Se solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and planewave density functional theory (DFT) calculations. The nature of the milling material and reaction atmosphere are shown to be essential factors in limiting the formation of undesired oxide byproducts. We demonstrate acquisition of 77 Se SSNMR spectra using different combinations of Carr-Purcell Meiboom-Gill acquisition (CPMG) pulse sequences, magic angle spinning (MAS), and MAS dynamic nuclear polarization. Further, the combination of SSNMR with the other characterization methods clearly demonstrates that high energy impact ball milling induces molecular level alloying of Mo, W and chalcogen atoms in the family Mo 1–x W x S y Se 2–y . Gauge including projector augmented wave DFT calculations yield accurate 77 Se chemical shift (CS) tensor components. 77 Se SSNMR spectroscopy was also applied to study the structure of WSe 2 nanocrystals intercalated with ethylenediamine. The intercalated WSe 2 nanocrystals exhibit a more positive isotropic 77 Se CS as compared to bulk WSe 2 , however, the 77 Se CS anisotropy is the same, confirming the WSe 2 layers have a similar structure as in their bulk counterparts.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMg6Zn by Materials Project

CsMg6Zn crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Cs is bonded in a 8-coordinate geometry to eight Mg and two equivalent Zn atoms. There are a spread of Cs–Mg bond distances ranging from 3.73–4.19 Å. There are one shorter (3.72 Å) and one longer (3.73 Å) Cs–Zn bond lengths. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 1-coordinate geometry to two equivalent Cs, five Mg, and one Zn atom. There are a spread of Mg–Mg bond distances ranging from 2.97–3.23 Å. The Mg–Zn bond length is 2.80 Å. In the second Mg site, Mg is bonded in a distorted body-centered cubic geometry to two equivalent Cs and six Mg atoms. There are a spread of Mg–Mg bond distances ranging from 3.21–3.28 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to one Cs, four Mg, and two equivalent Zn atoms. Both Mg–Zn bond lengths are 2.82 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to six Mg atoms. Zn is bonded in a 8-coordinate geometry to two equivalent Cs and six Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs2Hg3I8O by Materials Project

Cs2Hg3OI8 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Cs is bonded in a 1-coordinate geometry to one O and eight I atoms. The Cs–O bond length is 3.26 Å. There are a spread of Cs–I bond distances ranging from 4.05–4.38 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded to four I atoms to form corner-sharing HgI4 tetrahedra. There are a spread of Hg–I bond distances ranging from 2.77–2.93 Å. In the second Hg site, Hg is bonded to four I atoms to form corner-sharing HgI4 tetrahedra. There are two shorter (2.76 Å) and two longer (2.97 Å) Hg–I bond lengths. O is bonded in a bent 120 degrees geometry to two equivalent Cs atoms. There are five inequivalent I sites. In the first I site, I is bonded in a 1-coordinate geometry to two equivalent Cs and one Hg atom. In the second I site, I is bonded in a distorted single-bond geometry to two equivalent Cs and one Hg atom. In the third I site, I is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cs and two equivalent Hg atoms. In the fourth I site, I is bonded to three equivalent Cs and one Hg atom to form a mixture of distorted corner and edge-sharing ICs3Hg trigonal pyramids. In the fifth I site, I is bonded in a 2-coordinate geometry to one Cs and two Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsBrF4 by Materials Project

CsBrF4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to twelve F atoms. There are a spread of Cs–F bond distances ranging from 3.01–3.58 Å. There are two inequivalent Br sites. In the first Br site, Br is bonded in a square co-planar geometry to four equivalent F atoms. All Br–F bond lengths are 1.94 Å. In the second Br site, Br is bonded in a square co-planar geometry to four F atoms. There is two shorter (1.93 Å) and two longer (1.94 Å) Br–F bond length. There are three inequivalent F sites. In the first F site, F is bonded in a distorted trigonal planar geometry to two equivalent Cs and one Br atom. In the second F site, F is bonded in a 2-coordinate geometry to three equivalent Cs and one Br atom. In the third F site, F is bonded in a distorted single-bond geometry to four equivalent Cs and one Br atom.

36 MATERIALS SCIENCE↗