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At least 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Effect of anode ring arrangement on the spectroscopic characteristics of the NASA Lewis Bumpy Torus plasma

The modified Penning discharge in the NASA Lewis Bumpy Torus is normally produced by an anode ring at high voltage in each of the 12 magnetic mirror midplanes. For this investigation, the plasma was run with 12, 6, 3, and 1 anode rings. When 3 anode rings were used, the spectroscopically determined relative electron density and mean ion residence time increased by factors of 10 and 5, respectively, in one mode of operation. The discharge is observed to uniformly fill all bumps around the torus regardless of the anode arrangement and number. A plasma density on axis of 100 billion per cu cm is estimated for the 3-anode case in one mode of operation based on an observed discharge current to ion loss rate correlation and a measured mean ion residence time of .5 msec.

Richardson, R. W.↗
DOE OSTI2025

Trinuclear gold chains and octanuclear copper gyrobifastigia stabilized using a fluorinated pyridyl ligand

The fluorinated pyridyl ligand [6-(CF 3 )-2-Py] − with gold( I ) affords trinuclear Au 3 assemblies that further organize into a supramolecular helical column through aurophilic interactions. Its chemistry with copper( I ) is even more remarkable, leading to an unprecedented octanuclear copper–pyridyl cluster complex featuring a central Cu 8 core with an approximate gyrobifastigium geometry. Solid powders of compounds {(6-(CF 3 )-2-Py)Au} 3 and {(6-(CF 3 )-2-Py)Cu} 8 exhibit intense photoluminescence at room temperature, displaying green and yellow colors to the naked eye, respectively. Here, the octanuclear copper complex is also an effective catalyst for azide–alkyne cycloaddition, producing triazoles. Detailed computational analyses confirm the preference for experimental geometries and provide insights into the observed luminescence.

Phan, Vo Quang Huy [University of Texas at Arlingt↗
DOE OSTI2020

Additively manufactured novel Al-Cu-Sc-Zr alloy: Microstructure and mechanical properties

An in-depth understanding of microstructure and resultant properties is paramount in the design of a novel alloy system, especially for additive manufacturing (AM). The present investigation aims to characterize a prototypical AM Al alloy with great potential for structural applications. An Al-1.5Cu-0.8Sc-0.4Zr alloy designed using integrated computational material engineering was printed using the laser powder bed fusion AM process. This novel alloy shows promising combination of strength and ductility in as-built and peak-aged conditions. This improvement in the tensile properties is attributed to the presence of both coherent L1 2 Al 3 Sc/Al 3 (Sc,Zr) precipitates and Cu-rich regions. The microstructures were studied via extensive microscopy at different length scales using X-ray microscopy, scanning electron microscopy, and transmission electron microscopy. Fractography revealed that the columnar grain boundaries in as-built condition allow easy slip transfer as compared to the equiaxed grains, with the apex of the melt pool acting as the crack nucleation site. Furthermore, the peak aged condition resulted in improved strength while marginally sacrificing ductility due to precipitates decorating dislocations, grain boundaries and melt pool boundaries thus acting as obstacles to slip transfer.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Development of Corrosion Resistant Coatings for Structural Materials for Liquid Fueled Molten Salts Reactors Applications (Final Report)

Current structural alloys, code certified for the MSRs temperature ranges, contain high levels of chromium, making them highly susceptible to molten halide salt corrosion. One potential solution to circumvent the need for code certification of novel alloys, which is expensive and time consuming, is to design claddings that will protect the underlying code certified materials from corrosion damage during operation. In this work, we examined the corrosion of Ni and Cu electroplated, Ni and CuNi weld overlay, Mo-laser clad, and carburized claddings on SS316H for use in molten salt reactor environments. After characterization of the cladded materials (Task 1), static corrosion tests were used to assess corrosion resistance of the claddings in typical molten fluoride salts (Task 2). The corrosion tests were performed in molten FLiNaK at 700°C up to 1000 hours. Pre- and post-corrosion Scanning Electron Microscopy (SEM), energy-dispersive-spectroscopy (EDS), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and glow-discharge-optical-emission-spectroscopy (GDOES) were performed on cladding cross-sections and surfaces to evaluate degradation. The Cu and Ni electroplated samples, as well as the carburized samples, showed excellent corrosion resistance relative to the bare SS316H. To assess high temperature cladding stability, ageing experiments were performed at temperatures up to 900 C in inert atmosphere for the electroplated and carburized samples and a diffusion model was developed to predict long term cladding behavior (Task 3). It was found that the Cu cladding was basically insensitive to the high temperature ageing, except for small secondary phases forming at the interface. On the other hand, the Ni electroplated cladding experienced significant interdiffusion. Nevertheless, the gain in corrosion resistance for a 100μm Ni electroplated cladding is phenomenal, with more than 50% reduction in chromium dissolution from the substrate material for the first 15 years of salt exposure at 700°C. To assess radiation resistance and phase stability, high-temperature 4MeV Ni heavy ion irradiation was performed across the cladding/substrate interface up to 50 displacement-per-atom (DPA) at 500°C and 700°C to assess the phase stability and irradiation behaviors of the electroplated systems (Task 4). The Ni and Cu electroplated systems did not experience void swelling at the contrary to the SS316H substrate due to their nanocrystalline nature. Some level of recrystallization was observed in the cladding, as well as radiation induced segregation and enhanced diffusion. The interface acted as a potent sink for point defects with the presence of a void denuded zone. The mechanical properties of the claddings were assessed using thermal shock, micro-indentation, nano-indentation, and four-point bend testing experiments (Task 5). These experiments were performed on the claddings in as-received, corroded, irradiated, and thermally aged states to determine the effects of typical molten salt reactor environments on cladding integrity. No significant mass loss was observed after repeated thermal shocks. While the electroplated samples softened after high-temperature ageing, irradiation hardening compensate this effect, such that there is little different with the as-received materials. The results of these experiments suggest that the electroplated (copper/nickel) show the greatest promise for application in molten salt reactor development. These claddings prevented any chromium dissolution from occurring during the static corrosion experiments. Additionally, they demonstrated favorable properties for high temperature diffusion, phase stability, interfacial mechanical properties, and irradiation resistance. Weld-overlay cladding are also of great interest and could reach properties similar to the electroplated samples upon optimization (especially with multiple weld passes). The carburized SS316H showed excellent behavior as well, but more work needs to be done to assess their long-term stability. Finally, the Mo-laser clad system was not pursued further due to the manufacturing challenges. It is also worth noting that the Ni cladding systems should behave relatively well in terms of weldability since the Ni-weld overlay microstructure and associated corrosion rate are sound. While the NiCu weld-overlay has even lower corrosion rates than the Ni-weld overlay, more studies on welding of Cu-electroplated systems are necessary since Cu clusters are known to embrittle steels.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfGaCu by Materials Project

HfCuGa crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf is bonded to six equivalent Cu and six equivalent Ga atoms to form a mixture of face and edge-sharing HfGa6Cu6 cuboctahedra. All Hf–Cu bond lengths are 2.91 Å. All Hf–Ga bond lengths are 2.91 Å. Cu is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Ga atoms. All Cu–Ga bond lengths are 2.44 Å. Ga is bonded in a 3-coordinate geometry to six equivalent Hf and three equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrGaCu by Materials Project

ZrCuGa crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Zr is bonded to six equivalent Cu and six equivalent Ga atoms to form a mixture of edge and face-sharing ZrGa6Cu6 cuboctahedra. All Zr–Cu bond lengths are 2.93 Å. All Zr–Ga bond lengths are 2.93 Å. Cu is bonded in a 9-coordinate geometry to six equivalent Zr and three equivalent Ga atoms. All Cu–Ga bond lengths are 2.45 Å. Ga is bonded in a 3-coordinate geometry to six equivalent Zr and three equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc6CuTe2 by Materials Project

Sc6CuTe2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are six inequivalent Sc sites. In the first Sc site, Sc is bonded in a 4-coordinate geometry to one Cu and four Te atoms. The Sc–Cu bond length is 3.30 Å. There are a spread of Sc–Te bond distances ranging from 2.92–3.12 Å. In the second Sc site, Sc is bonded in a 1-coordinate geometry to one Cu and one Te atom. The Sc–Cu bond length is 3.12 Å. The Sc–Te bond length is 2.96 Å. In the third Sc site, Sc is bonded in a 5-coordinate geometry to three equivalent Cu and two equivalent Te atoms. There are two shorter (2.78 Å) and one longer (3.00 Å) Sc–Cu bond lengths. Both Sc–Te bond lengths are 3.01 Å. In the fourth Sc site, Sc is bonded to two equivalent Cu and three Te atoms to form distorted edge-sharing ScCu2Te3 trigonal bipyramids. Both Sc–Cu bond lengths are 2.72 Å. There are one shorter (2.92 Å) and two longer (2.99 Å) Sc–Te bond lengths. In the fifth Sc site, Sc is bonded in a 4-coordinate geometry to four Te atoms. There are two shorter (2.94 Å) and two longer (2.96 Å) Sc–Te bond lengths. In the sixth Sc site, Sc is bonded in a 3-coordinate geometry to two equivalent Cu and one Te atom. Both Sc–Cu bond lengths are 2.79 Å. The Sc–Te bond length is 3.03 Å. Cu is bonded in a 9-coordinate geometry to nine Sc atoms. There are two inequivalent Te sites. In the first Te site, Te is bonded in a 8-coordinate geometry to eight Sc atoms. In the second Te site, Te is bonded to seven Sc atoms to form distorted edge-sharing TeSc7 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsCu(BiS2)2 by Materials Project

CsBi2CuS4 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Cs1+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Cs–S bond distances ranging from 3.47–3.77 Å. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two BiS6 octahedra, corners with two equivalent CuS4 tetrahedra, and edges with four BiS6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Cu–S bond distances ranging from 2.28–2.72 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six S2- atoms to form BiS6 octahedra that share corners with three equivalent BiS6 octahedra, a cornercorner with one CuS4 tetrahedra, edges with five BiS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 3–25°. There are a spread of Bi–S bond distances ranging from 2.67–3.12 Å. In the second Bi3+ site, Bi3+ is bonded to six S2- atoms to form distorted BiS6 octahedra that share corners with three equivalent BiS6 octahedra, a cornercorner with one CuS4 tetrahedra, edges with five BiS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 3–25°. There are a spread of Bi–S bond distances ranging from 2.67–3.27 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to one Cs1+ and four Bi3+ atoms to form distorted SCsBi4 square pyramids that share corners with eight SCs2CuBi3 octahedra, edges with four SCs2CuBi3 octahedra, and edges with two equivalent SCsBi4 square pyramids. The corner-sharing octahedra tilt angles range from 2–81°. In the second S2- site, S2- is bonded to two equivalent Cs1+, one Cu1+, and three Bi3+ atoms to form distorted SCs2CuBi3 octahedra that share corners with two equivalent SCs2CuBi3 octahedra, corners with six equivalent SCsBi4 square pyramids, edges with four SCs2CuBi3 octahedra, an edgeedge with one SCsBi4 square pyramid, and a faceface with one SCs2CuBi3 octahedra. The corner-sharing octahedral tilt angles are 68°. In the third S2- site, S2- is bonded to two equivalent Cs1+, one Cu1+, and three Bi3+ atoms to form distorted SCs2CuBi3 octahedra that share corners with two equivalent SCs2CuBi3 octahedra, corners with two equivalent SCsBi4 square pyramids, edges with four SCs2CuBi3 octahedra, edges with three equivalent SCsBi4 square pyramids, and a faceface with one SCs2CuBi3 octahedra. The corner-sharing octahedral tilt angles are 68°. In the fourth S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Cs1+, two equivalent Cu1+, and two Bi3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2(CuSn)3 by Materials Project

Ce2(CuSn)3 crystallizes in the tetragonal P4/mmm space group. The structure is one-dimensional and consists of one Ce2(CuSn)3 ribbon oriented in the (0, 0, 1) direction. Ce is bonded in a linear geometry to one Cu and one Sn atom. The Ce–Cu bond length is 2.62 Å. The Ce–Sn bond length is 2.93 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a linear geometry to one Ce and one Sn atom. The Cu–Sn bond length is 2.47 Å. In the second Cu site, Cu is bonded in a linear geometry to two equivalent Sn atoms. Both Cu–Sn bond lengths are 2.47 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a linear geometry to one Ce and one Cu atom. In the second Sn site, Sn is bonded in a linear geometry to two equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaCu2(PO4)2 by Materials Project

BaCu2(PO4)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 4-coordinate geometry to one P5+ and eight O2- atoms. The Ba–P bond length is 2.80 Å. There are a spread of Ba–O bond distances ranging from 2.65–3.31 Å. In the second Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to three O2- atoms. There are a spread of Ba–O bond distances ranging from 2.58–2.73 Å. There are four inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a 2-coordinate geometry to one P5+ and three O2- atoms. The Cu–P bond length is 2.01 Å. There are a spread of Cu–O bond distances ranging from 1.60–2.72 Å. In the second Cu2+ site, Cu2+ is bonded in a 3-coordinate geometry to one P5+ and four O2- atoms. The Cu–P bond length is 1.72 Å. There are a spread of Cu–O bond distances ranging from 1.60–2.41 Å. In the third Cu2+ site, Cu2+ is bonded in a 1-coordinate geometry to three O2- atoms. There are a spread of Cu–O bond distances ranging from 1.57–2.43 Å. In the fourth Cu2+ site, Cu2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Cu–O bond distances ranging from 1.60–1.74 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a 2-coordinate geometry to one Ba2+ and four O2- atoms. There are a spread of P–O bond distances ranging from 1.09–2.31 Å. In the second P5+ site, P5+ is bonded in a 2-coordinate geometry to one Cu2+ and four O2- atoms. There are a spread of P–O bond distances ranging from 1.51–2.35 Å. In the third P5+ site, P5+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.42–2.41 Å. In the fourth P5+ site, P5+ is bonded in a 2-coordinate geometry to one Cu2+ and four O2- atoms. There are a spread of P–O bond distances ranging from 1.34–2.35 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Cu2+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+, one P5+, and one O2- atom. The O–O bond length is 1.97 Å. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Cu2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cu2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Cu2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to one Ba2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent Ba2+, one Cu2+, one P5+, and two O2- atoms. The O–O bond length is 2.35 Å. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, one Cu2+, one P5+, and one O2- atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Cu2+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, one Cu2+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted L-shaped geometry to one Cu2+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ba2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

A Ba 6 Cu 31 Te 22 ( A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

In this study, hree polyanionic tellurides, ABa 6 Cu 31 Te 22 (A = K, Rb, Cs), were synthesized in salt flux. The isostructural tellurides crystallize in a new structure type, in the cubic Pa$\overline{3}$ space group with a Wyckoff sequence of d 10 c 2 b 1 and large unit cell volumes of over 5500 Å 3 . The structures feature a framework of [CuTe 4 ] tetrahedra and [CuTe 3 ] trigonal pyramids with disorder in the Cu sites. The polyanionic frameworks have large square antiprism and cuboctahedral voids where Ba and alkali metal cations are situated, forming [BaTe 8 ] and [ATe 12 ], respectively. The overall compositions are close to being charge balanced. The large [ATe 12 ] cuboctahedra allowed for significant anisotropic displacement of the A cations, as observed from both single crystal X-ray diffraction and heat capacity studies. Alkali cations rattling together with Cu atom displacement and disorder leads to the dispersion of phonons, thus softening the lattice and subsequently reducing the thermal conductivity. Evaluations of the electronic band structure revealed the occurrence of a narrow bandgap together with the presence of a flat band near the valence band maximum, giving rise to the high thermopower. The Cs and Rb analogues show a slope change in the temperature dependence of electrical resistivity around room temperature, which is typical for semimetals or degenerate semiconductors. For the as-synthesized and unoptimized materials, high values of the thermoelectric figure-of-merit of ~0.2 were observed at 623 K.

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

Carboxylic Group Rotation and Lattice Expansion in a Co 2 (Pyrazine-2,3-Dicarboxylate) 2 (4,4'-Bipyridine) Porous Coordination Polymer Induced by CO 2 Adsorption at Ambient Temperature

Here, a Co 2 (pzdc) 2 (bpy)(H 2 O) m (pzdc: pyrazine-2,3dicarboxylate; bpy: 4,4'-bipyridine) porous coordination polymer (PCP) was studied for CO 2 uptake and concomitant structural changes at ambient temperature. Extended structural characterization included evaluation of lattice parameter changes upon CO 2 adsorption and in situ synchrotron X-ray powder diffraction data. The PCP effective pore size increased by ~2% with gas uptake over the pressure range of 1-50 atm, allowing the adsorption capacity to double. Furthermore, the hysteretic behaviors seen during CO 2 adsorption at moderate pressures are commensurate with the structural changes from synchrotron data. The adsorption and hysteresis occur with rotation of the linking carboxylate groups, and yet only minor changes in unit cell volume (ΔV ≈ 6 Å 3 ) are observed. This contrasts the findings for [Cu 2 (pzdc) 2 (bpy)] n , where a combination of pillar bpy rotations and significant lattice expansion (ΔV ≈ 68 Å(3)) takes place upon hysteretic adsorption of CO 2 . In situ high-temperature X-ray diffraction revealed that the Co(II)-based material has good thermal stability up to ca. 200° C. Finally, the CO 2 uptake also appears to be at a physisorption level, with adsorbent-adsorbate interactions that are ca. 30% stronger than what has been reported for CO 2 adsorption onto [Cu 2 (pzdc) 2 (bpy)] n .

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

High Critical Current Density in Internally-oxidized Nb 3 Sn Superconductors and its Origin

In this paper, we report achievement of non-Cu-matrix critical current density $(J_c)$ in internally-oxidized Nb 3 Sn superconductors that surpasses the best state-of-the-art Nb 3 Sn and the $J_c$ specification of the Future Circular Collider. We then explore the mechanism of the improvement, which was believed to be caused by refined grain size. However, our experiment showed that even with similar grain size, internally-oxidized wires had significantly higher $J_c$ than non-oxidized wires. This, combined with transmission electron microscopy and atom probe tomography studies which showed a high density of intragranular nano-precipitates with suitable sizes as pinning centers in internally-oxidized wires, demonstrates a significant contribution from the nano-precipitates.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Materials Data on Li8Fe7Cu(PO4)12 by Materials Project

Li8Fe7Cu(PO4)12 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Li sites. In the first Li site, Li is bonded to four O atoms to form distorted LiO4 trigonal pyramids that share corners with four PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Li–O bond distances ranging from 1.96–2.00 Å. In the second Li site, Li is bonded to four O atoms to form distorted LiO4 trigonal pyramids that share corners with four PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Li–O bond distances ranging from 1.95–2.00 Å. In the third Li site, Li is bonded to four O atoms to form distorted LiO4 trigonal pyramids that share corners with four PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Li–O bond distances ranging from 1.95–2.00 Å. In the fourth Li site, Li is bonded to four O atoms to form distorted LiO4 trigonal pyramids that share corners with four PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Li–O bond distances ranging from 1.95–2.00 Å. In the fifth Li site, Li is bonded in a distorted see-saw-like geometry to four O atoms. There are a spread of Li–O bond distances ranging from 1.96–2.00 Å. In the sixth Li site, Li is bonded in a distorted see-saw-like geometry to four O atoms. There are a spread of Li–O bond distances ranging from 1.96–1.99 Å. In the seventh Li site, Li is bonded to four O atoms to form distorted LiO4 trigonal pyramids that share corners with four PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Li–O bond distances ranging from 1.95–2.00 Å. In the eighth Li site, Li is bonded to four O atoms to form distorted LiO4 trigonal pyramids that share corners with four PO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one CuO6 octahedra. There are a spread of Li–O bond distances ranging from 1.92–2.01 Å. There are seven inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two LiO4 trigonal pyramids. There are a spread of Fe–O bond distances ranging from 1.95–2.07 Å. In the second Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two LiO4 trigonal pyramids. There are a spread of Fe–O bond distances ranging from 1.95–2.08 Å. In the third Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two LiO4 trigonal pyramids. There are a spread of Fe–O bond distances ranging from 1.95–2.09 Å. In the fourth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two LiO4 trigonal pyramids. There are a spread of Fe–O bond distances ranging from 1.95–2.09 Å. In the fifth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO4 trigonal pyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.09 Å. In the sixth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO4 trigonal pyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.09 Å. In the seventh Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO4 trigonal pyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.08 Å. Cu is bonded to six O atoms to form CuO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO4 trigonal pyramid. There are a spread of Cu–O bond distances ranging from 1.94–2.12 Å. There are twelve inequivalent P sites. In the first P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra and corners with three LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 10–43°. There is one shorter (1.53 Å) and three longer (1.55 Å) P–O bond length. In the second P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra and corners with three LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 10–42°. There is one shorter (1.53 Å) and three longer (1.55 Å) P–O bond length. In the third P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CuO6 octahedra, corners with three FeO6 octahedra, and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 10–45°. There is one shorter (1.53 Å) and three longer (1.55 Å) P–O bond length. In the fourth P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 10–42°. There is one shorter (1.54 Å) and three longer (1.55 Å) P–O bond length. In the fifth P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CuO6 octahedra, corners with three FeO6 octahedra, and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 10–42°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. In the sixth P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CuO6 octahedra, corners with three FeO6 octahedra, and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 16–43°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. In the seventh P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CuO6 octahedra, corners with three FeO6 octahedra, and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 11–43°. There is one shorter (1.54 Å) and three longer (1.55 Å) P–O bond length. In the eighth P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 10–43°. There is one shorter (1.53 Å) and three longer (1.55 Å) P–O bond length. In the ninth P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CuO6 octahedra, corners with three FeO6 octahedra, and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 25–35°. There are a spread of P–O bond distances ranging from 1.52–1.56 Å. In the tenth P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 26–34°. There is two shorter (1.53 Å) and two longer (1.55 Å) P–O bond length. In the eleventh P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra and corners with two LiO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 26–35°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. In the twelfth P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CuO6 octahedra and corners with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 26–38°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. There are forty-eight inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Fe and one P atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Fe and one P atom. In the third O site, O is bonded in a 3-coordinate geometry to one Li, one Fe, and one P atom. In the fourth O site, O is bonded in a 3-coordinate geometry to one Li, one Fe, and one P atom. In the fifth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the sixth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the seventh O site, O is bonded in a linear geometry to one Fe and one P atom. In the eighth O site, O is bonded in a linear geometry to one Fe and one P atom. In the ninth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the tenth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the eleventh O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the twelfth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirteenth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the fourteenth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the fifteenth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the sixteenth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the seventeenth O site, O is bonded in a linear geometry to one Fe and one P atom. In the eighteenth O site, O is bonded in a linear geometry to one Fe and one P atom. In the nineteenth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the twentieth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the twenty-first O site, O is bonded in a 3-coordinate geometry to one Li, one Fe, and one P atom. In the twenty-second O site, O is bonded in a 3-coordinate geometry to one Li, one Fe, and one P atom. In the twenty-third O site, O is bonded in a bent 150 degrees geometry to one Fe and one P atom. In the twenty-fourth O site, O is bonded in a bent 150 degrees geometry to one Fe and one P atom. In the twenty-fifth O site, O is bonded in a bent 150 degrees geometry to one Fe and one P atom. In the twenty-sixth O site, O is bonded in a bent 150 degrees geometry to one Fe and one P atom. In the twenty-seventh O site, O is bonded in a 3-coordinate geometry to one Li, one Cu, and one P atom. In the twenty-eighth O site, O is bonded in a 3-coordinate geometry to one Li, one Fe, and one P atom. In the twenty-ninth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirtieth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirty-first O site, O is bonded in a linear geometry to one Fe and one P atom. In the thirty-second O site, O is bonded in a linear geometry to one Cu and one P atom. In the thirty-third O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirty-fourth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Cu, and one P atom. In the thirty-fifth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirty-sixth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirty-seventh O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the thirty-eighth O site, O is bonded in a 3-coordinate geometry to one Li, one Cu, and one P atom. In the thirty-ninth O site, O is bonded in a distorted trigonal planar geometry to one Li, one Fe, and one P atom. In the fortieth O site, O is bonded in a distorted trigonal non-coplanar geometry to one Li, one Fe, and one P atom. In the forty-first O site, O is bonded in a linear geometry to one Fe and one P atom. In the forty-second O site, O is bonded in a linear geometry to one Fe and one P atom. In the forty-third O site, O is bonded in a distorted trigonal planar g

36 MATERIALS SCIENCE↗
DOE OSTI2022

Direct Observation of Ammonia Storage in UiO-66 Incorporating Cu(II) Binding Sites

The presence of active sites in metal–organic framework (MOF) materials can control and affect their performance significantly in adsorption and catalysis. However, revealing the interactions between the substrate and active sites in MOFs at atomic precision remains a challenging task. Here, we report the direct observation of binding of NH 3 in a series of UiO-66 materials containing atomically dispersed defects and open Cu(I) and Cu(II) sites. While all MOFs in this series exhibit similar surface areas (1111–1135 m 2 g –1 ), decoration of the -OH site in UiO-66-defect with Cu(II) results in a 43% enhancement of the isothermal uptake of NH 3 at 273 K and 1.0 bar from 11.8 in UiO-66-defect to 16.9 mmol g –1 in UiO-66-Cu II . A 100% enhancement of dynamic adsorption of NH 3 at a concentration level of 630 ppm from 2.07 mmol g –1 in UiO-66-defect to 4.15 mmol g –1 in UiO-66-Cu II at 298 K is observed. In situ neutron powder diffraction, inelastic neutron scattering, and electron paramagnetic resonance, solid-state nuclear magnetic resonance, and infrared spectroscopies, coupled with modeling reveal that the enhanced NH 3 uptake in UiO-66-Cu II originates from a {Cu(II)···NH 3 } interaction, with a reversible change in geometry at Cu(II) from near-linear to trigonal coordination. This work represents the first example of structural elucidation of NH 3 binding in MOFs containing open metal sites and will inform the design of new efficient MOF sorbents by targeted control of active sites for NH 3 capture and storage.

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

The effect of composition, temperature and pressure on the oxidation state and coordination environment of copper in silicate melts

Copper is a redox variable element that may occur as Cu 0 , Cu + , and Cu 2+ in the Earth’s crust. The oxidation state will affect its partitioning between coexisting minerals, melts and fluids and hence its behaviour in magmatic processes. Copper bearing silicate glasses were quenched from melts with 23 synthetic compositions (19 CaO-Na 2 O-MgO-Al 2 O 3 -SiO 2 (CNMAS), two “granites” containing K 2 O ± H 2 O, and Fe-bearing “MORB” and “andesite”) equilibrated at oxygen fugacities (fO 2 ), expressed in log units relative to the fayalite-magnetite-quartz (FMQ) buffer, ranging from −0.7 to 14, temperatures from 900 to 1500 °C and pressures from 0 to 2.5 GPa. Cu K-edge X-ray absorption near edge structure (XANES) spectra were recorded from the glasses and a pre-edge feature in the XANES spectra was found to scale with the proportion of Cu + . Cu + /ΣCu (where ΣCu = Cu + + Cu 2+ ) was quantified by fitting the intensity of the pre-edge feature as a function of fO 2 to the thermodynamically expected relationship. Cu + /ΣCu was found to only weakly depend on melt composition, with more basic melts (e.g., basalts rather than granites) preferentially stabilising Cu 2+ . Increasing temperature stabilises Cu + , while increasing pressure had little effect on Cu + /ΣCu in CNMAS melts but preferentially stabilised Cu 2+ in granite melts. Cu + /ΣCu can be predicted in silicate melts by the empirical equation: log(Cu 2+ /Cu + ) = 0.25(ΔFMQ + 8.58 − 25050/T + 940P/T – 0.02P) − 4.73 + 5400/T + 1.99Λ + (280P – 90P2) where T is temperature in K, P is pressure in GPa and is the optical basicity of the composition. The effects of fO 2 , melt composition, temperature and pressure on Cu + /ΣCu indicate that Cu + will be the dominant oxidation state in terrestrial silicate melts (e.g., Cu + /ΣCu = 99% in an andesitic melt at 900 °C, 1 GPa and ΔFMQ = 1). The electron exchange reaction Cu 2+ + Fe 2+ → Cu + + Fe 3+ occurs on cooling and, given the abundance of Fe in natural melts, the oxidation state of Cu in natural glasses is unlikely to correspond to that in the original melt.

Copper↗
DOE OSTI2021

Next Generation Cuprous Phenanthroline MLCT Photosensitizer Featuring Cyclohexyl Substituents

A new long–lived, visible light–absorbing homoleptic Cu(I) metal–to–ligand charge transfer (MLCT) photosensitizer [Cu(dchtmp) 2 ]PF 6 (dchtmp = 2,9–dicyclohexyl–3,4,7,8–tetramethyl–1,10–phenanthroline), has been synthesized, structurally characterized, and evaluated in terms of its molecular photophysics, electrochemistry, and electronic structure. Static and time–resolved transient absorption (TA) and photoluminescence (PL) spectroscopy measured on the title compound in CH 2 Cl 2 (τ = 2.6 μs, Φ PL = 5.5%), CH 3 CN (τ = 1.5 μs, Φ PL = 2.6%), and THF (τ = 2.0 μs, Φ PL = 3.7%) yielded impressive photophysical metrics even when dissolved in Lewis basic solvents. The combined static spectroscopic data along with ultrafast TA experiments revealed that the pseudo–Jahn–Teller distortion and intersystem crossing dynamics in the MLCT excited state displayed characteristics of being sterically arrested throughout its evolution. Here, electrochemical and static PL data illustrate that [Cu(dchtmp) 2 ]PF 6 is a potent photoreductant (–1.77 V vs. Fc +/o in CH 3 CN) equal to or greater than all previously investigated homoleptic Cu(I) diimine complexes. Although we successfully prepared the cyclopentyl analog dcptmp (2,9–dicyclopentyl–3,4,7,8–tetramethyl–1,10–phenanthroline) using the same C–C radical coupling photochemistry as dchtmp, the corresponding Cu(I) complex could not be isolated due to the steric hinderance presented at the metal center. Ultimately, the successful preparation of [Cu(dchtmp) 2 ] + represents a major step forward for the design and discovery of novel earth–abundant photosensitizers made possible through a newly conceived ligand synthetic strategy.

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

Facet Impact of CuMn 2 O 4 Spinel Nanocatalysts on Enhancement of the Oxygen Reduction Reaction in Alkaline Media

Surface-structure engineering represents an attractive strategy to optimize the energy conversion performance of nanocatalysts using their deliberately controlled exposed facets. To further exploit the potential of non-PGM-based spinel catalysts for alkaline oxygen reduction reaction (ORR), a cathodic fuel cell reaction, we hereby report a strategy of ORR improvement by controlling the crystallographic facets of ultra-small CuMn 2 O 4 spinel nanocatalysts through a developed colloidal synthesis approach. The synthesis of CuMn 2 O 4 nanocrystals with morphological control relies on the design and selection of the Cu-/Mn-precursors with striking discrepancies in reaction kinetics. Following carbon loading and an annealing post-treatment of the as-synthesized nanocatalysts, the exclusively {101} facet-exposed CuMn 2 O 4 spinel nano-octahedra exhibit improved electrocatalytic activity toward ORR in 1 M KOH, when compared to their spherical counterparts, exhibiting a mass activity (MA) of 37.6 A/g at 0.85 V. After 10,000 cycles of ORR durability test, the nano-octahedra still retain an MA of 24.5 A/g, which is twice that of the CuMn 2 O 4 spinel nanospheres. Structural characterizations after durability testing indicate that the MA decay is likely associated with a decrease in the Mn 3+ fraction and the emergence of Cu + on CuMn 2 O 4 nano-octahedral surfaces. Finally, as a paradigm, this synthesis approach could be extended to other Mn-based spinel nanocatalysts with precise shape control, enabling us to understand and establish the relationship between the surface lattice/valence state and electrocatalytic properties.

36 MATERIALS SCIENCE↗