Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “U(OF)2”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on U(CuSn)2 by Materials Project

UCu2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.35 Å) and four longer (3.38 Å) U–Cu bond lengths. There are four shorter (3.32 Å) and four longer (3.50 Å) U–Sn bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to four equivalent U and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.59 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent U and five Sn atoms. There are one shorter (2.47 Å) and four longer (2.61 Å) Cu–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent U and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent U and five Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(Fe5Si)2 by Materials Project

UFe10Si2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of U–Fe bond distances ranging from 2.85–3.17 Å. All U–Si bond lengths are 3.09 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded in a 8-coordinate geometry to one U, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.38–2.91 Å. Both Fe–Si bond lengths are 2.58 Å. In the second Fe site, Fe is bonded in a 10-coordinate geometry to one U, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.44–2.68 Å. Both Fe–Si bond lengths are 2.54 Å. In the third Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent U, eight Fe, and two equivalent Si atoms. All Fe–Fe bond lengths are 2.46 Å. Both Fe–Si bond lengths are 2.56 Å. In the fourth Fe site, Fe is bonded to two equivalent U, eight Fe, and two equivalent Si atoms to form a mixture of distorted corner, edge, and face-sharing FeU2Fe8Si2 cuboctahedra. Both Fe–Fe bond lengths are 2.36 Å. Both Fe–Si bond lengths are 2.36 Å. Si is bonded in a 12-coordinate geometry to two equivalent U and ten Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(GeIr)2 by Materials Project

UIr2Ge2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.18 Å) and four longer (3.36 Å) U–Ir bond lengths. There are four shorter (3.23 Å) and four longer (3.24 Å) U–Ge bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent U and four equivalent Ge atoms to form distorted IrU4Ge4 tetrahedra that share corners with twelve equivalent GeU4Ir4 tetrahedra, edges with two equivalent GeU4Ir4 tetrahedra, edges with four equivalent IrU4Ge4 tetrahedra, and faces with four equivalent IrU4Ge4 tetrahedra. All Ir–Ge bond lengths are 2.50 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent U and five Ge atoms. There are one shorter (2.40 Å) and four longer (2.49 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded to four equivalent U and four equivalent Ir atoms to form distorted GeU4Ir4 tetrahedra that share corners with twelve equivalent IrU4Ge4 tetrahedra, edges with two equivalent IrU4Ge4 tetrahedra, edges with four equivalent GeU4Ir4 tetrahedra, and faces with four equivalent GeU4Ir4 tetrahedra. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent U and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(Co5Si)2 by Materials Project

UCo10Si2 crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. U is bonded in a 4-coordinate geometry to sixteen Co and four equivalent Si atoms. There are a spread of U–Co bond distances ranging from 2.82–3.08 Å. All U–Si bond lengths are 3.15 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded in a 10-coordinate geometry to one U, seven Co, and two equivalent Si atoms. There are a spread of Co–Co bond distances ranging from 2.48–2.61 Å. Both Co–Si bond lengths are 2.46 Å. In the second Co site, Co is bonded in a 12-coordinate geometry to two equivalent U, eight Co, and two equivalent Si atoms. There are a spread of Co–Co bond distances ranging from 2.38–2.66 Å. Both Co–Si bond lengths are 2.36 Å. In the third Co site, Co is bonded to two equivalent U and ten Co atoms to form CoU2Co10 cuboctahedra that share corners with four equivalent SiU2Co8Si2 cuboctahedra, corners with six equivalent CoU2Co10 cuboctahedra, edges with four equivalent SiU2Co8Si2 cuboctahedra, faces with two equivalent CoU2Co10 cuboctahedra, and faces with four equivalent SiU2Co8Si2 cuboctahedra. Both Co–Co bond lengths are 2.42 Å. Si is bonded to two equivalent U, eight Co, and two equivalent Si atoms to form distorted SiU2Co8Si2 cuboctahedra that share corners with four equivalent CoU2Co10 cuboctahedra, corners with six equivalent SiU2Co8Si2 cuboctahedra, edges with four equivalent CoU2Co10 cuboctahedra, faces with two equivalent SiU2Co8Si2 cuboctahedra, and faces with four equivalent CoU2Co10 cuboctahedra. Both Si–Si bond lengths are 2.42 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Simultaneous imaging of two-phase velocities in particle-laden flows by two-color optical phase discrimination

In this Letter, we present a particle image/tracking velocimetry (PIV/PTV) technique for simultaneous velocity measurement of both fluid and particle phases, adopting newly developed optical phase discrimination methods and novel optical particles. Spherical acrylic (PMMA) particles of diameter ∼ <#comment/> O ( 100 µ <#comment/> m ) were used as the particle phase, while fine B A M : E u 2 + phosphors of diameter ∼ <#comment/> O ( 1 µ <#comment/> m ) were used as the fluid tracer. Under Nd:YAG 355 nm laser excitation, both the laser-induced fluorescence (LIF) from PMMA and laser-induced phosphorescence (LIP) from B A M : E u 2 + provided sufficiently strong signals for PIV imaging with two non-intensified cameras and were clearly separable for phase discrimination using spectral filters and temporal profiles. The advantages of the PIV/PTV method include the relatively low cost of B A M : E u 2 + phosphors, high sphericity and narrow size distribution of PMMA particles with LIF emission, and direct optical discrimination eliminating artifacts, while requiring much less computational capacity for PIV/PTV processing of complex particle-laden flows.

Bi, Xiaopeng (ORCID:0000000190847325)↗
DOE OSTI2020

Materials Data on U(Fe2Ge)2 by Materials Project

UFe4Ge2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. U is bonded in a 10-coordinate geometry to four equivalent Fe and six equivalent Ge atoms. All U–Fe bond lengths are 2.95 Å. There are two shorter (2.89 Å) and four longer (2.92 Å) U–Ge bond lengths. Fe is bonded in a 3-coordinate geometry to one U and three equivalent Ge atoms. There are two shorter (2.47 Å) and one longer (2.48 Å) Fe–Ge bond lengths. Ge is bonded in a 9-coordinate geometry to three equivalent U and six equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(Mn2P)2 by Materials Project

UMn4P2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. U is bonded to six equivalent P atoms to form a mixture of distorted edge and corner-sharing UP6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are two shorter (2.80 Å) and four longer (2.82 Å) U–P bond lengths. Mn is bonded in a 3-coordinate geometry to three equivalent P atoms. There are one shorter (2.29 Å) and two longer (2.33 Å) Mn–P bond lengths. P is bonded in a 9-coordinate geometry to three equivalent U and six equivalent Mn atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1985

SU(2) x U(1) vacuum and the Centauro events

It is proposed that the fireballs invoked to explain the Centauro events are bubbles of a metastable superdense state of nuclear matter, created in high energy (E approximately 10 to the 15th power eV) cosmic ray collisions at the top of the atmosphere. If these bubbles are created with a Lorentz factor gamma approximately equals 10 at their CM frame, the objections against the origin of these events in cosmic ray interactions are overcome. A relationship then between their lifetime, tau, and the threshold energy for bubble formation, E sub th, appears to be insensitive to the value of tau and always close to E sub th approximately 10 to 15th power eV. Finally it is speculated that these bubbles might be manifestations of the SU(2) x U(1) false vacuum excited in these collisions. The absence of in the Centauro events is then explained by the decay modes of these excitations.

Kazanas, D.↗
DOE OSTI2020

Materials Data on U(Al10V)2 by Materials Project

UV2Al20 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. U is bonded in a 4-coordinate geometry to sixteen Al atoms. There are four shorter (3.13 Å) and twelve longer (3.17 Å) U–Al bond lengths. V is bonded to twelve Al atoms to form VAl12 cuboctahedra that share corners with six equivalent VAl12 cuboctahedra, edges with eighteen equivalent AlUAl10V cuboctahedra, and faces with six equivalent AlUAl10V cuboctahedra. There are six shorter (2.56 Å) and six longer (2.82 Å) V–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a distorted linear geometry to two equivalent U and twelve equivalent Al atoms. All Al–Al bond lengths are 3.07 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to two equivalent V and ten Al atoms. There are a spread of Al–Al bond distances ranging from 2.72–2.85 Å. In the third Al site, Al is bonded to one U, one V, and ten Al atoms to form distorted AlUAl10V cuboctahedra that share corners with fifteen equivalent AlUAl10V cuboctahedra, edges with two equivalent AlUAl10V cuboctahedra, edges with three equivalent VAl12 cuboctahedra, a faceface with one VAl12 cuboctahedra, and faces with fifteen equivalent AlUAl10V cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.67–2.93 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(H2O3)2 by Materials Project

UO2(OH)4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. U is bonded to eight O atoms to form distorted edge-sharing UO8 hexagonal bipyramids. There are a spread of U–O bond distances ranging from 1.80–2.44 Å. There are two inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.00 Å) and one longer (1.76 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. There are four inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one U atom. In the second O site, O is bonded in a single-bond geometry to one U atom. In the third O site, O is bonded in a 4-coordinate geometry to two equivalent U, one H, and one O atom. The O–O bond length is 1.45 Å. In the fourth O site, O is bonded in a distorted water-like geometry to one U and two H atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1984

SU(2) x U(1) vacuum and the Centauro events

It is proposed that the fireballs invoked to explain the Centauro events are bubbles of a metastable superdense state of nuclear matter, created in high energy (E is approximately 10 to the 15th power eV) cosmic ray collisions at the top of the atmosphere. If these bubbles are created with a Lorentz factor gamma approximately = 10 at their CM frame, the objections against the origin of these events in cosmic ray interactions are overcome. Assuming further, that the Centauro events are to the explosive decay of these metastable bubbles, a relationship between their lifetime, tau, and the threshold energy for bubble formation, E sub th, is derived. The minimum lifetime consistent with such an interpretation in tau is approximately 10 to the -8th power sec, while the E sub th appears to be insensitive to the value of tau and always close to E sub th is approximately 10 to the 15th power eV. Finally it is speculated that if the available CM energy is thermalized in such collisions, these bubbles might be manifestations of excitations of the SU(2) x U(1) false vacuum. The absence of neutral pions in the Centauro events is then explained by the decay of these excitations.

Kazanas, D.↗
DOE OSTI2021

High temperature mechanical properties of fluorite crystal structured materials (CeO 2 , ThO 2 , and UO 2 ) and advanced accident tolerant fuels (U 3 Si 2 , UN, and UB 2 )

The mechanical interaction between the fuel and cladding that occurs during operation of a nuclear reactor is important to understand as it can lead to cladding failures and release of radioactive material into the coolant. Additionally, in order to develop better models of the pellet-clad mechanical interactions, the mechanical properties of the fuel at relevant operating temperatures, like the elastic moduli, are needed for current and advanced accident tolerant fuels (ATFs). In this work, elevated temperature nanoindentation and resonant ultrasound spectroscopy were used to measure the moduli and hardness of several fluorite materials (CeO 2 , ThO 2 , UO 2 ) and several ATF candidates (ATF) (U 3 Si 2 , UN, UB 2 ). In addition, a comparison of the two techniques was performed in this study to independently validate the mechanical properties.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Theory of the tertiary instability and the Dimits shift within a scalar model

The Dimits shift is the shift between the threshold of the drift-wave primary instability and the actual onset of turbulent transport in a magnetized plasma. It is generally attributed to the suppression of turbulence by zonal flows, but developing a more detailed understanding calls for consideration of specific reduced models. The modified Terry–Horton system has been proposed by St-Onge ( J. Plasma Phys. , vol. 83, 2017, 905830504) as a minimal model capturing the Dimits shift. Here, we use this model to develop an analytic theory of the Dimits shift and a related theory of the tertiary instability of zonal flows. We show that tertiary modes are localized near extrema of the zonal velocity $U(x)$ , where $x$ is the radial coordinate. By approximating $U(x)$ with a parabola, we derive the tertiary-instability growth rate using two different methods and show that the tertiary instability is essentially the primary drift-wave instability modified by the local $U'' \doteq {\rm d}^2 U/{\rm d} x^2 $ . Then, depending on $U''$ , the tertiary instability can be suppressed or unleashed. The former corresponds to the case when zonal flows are strong enough to suppress turbulence (Dimits regime), while the latter corresponds to the case when zonal flows are unstable and turbulence develops. This understanding is different from the traditional paradigm that turbulence is controlled by the flow shear $| {\rm d} U / {\rm d} x |$ . Our analytic predictions are in agreement with direct numerical simulations of the modified Terry–Horton system.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Hydrolysis of Small Oxo/Hydroxo Molecules Containing High Oxidation State Actinides (Th, Pa, U, Np, Pu): A Computational Study

The energetics of hydrolysis reactions for high oxidation states of oxo/hydroxo monomeric actinide species (Th IV O 2 , Pa IV O 2 , U IV O 2 , Pa V O 2 (OH), U V O 2 (OH), U VI O 3 , Np VI O 3 , Np VII O 3 (OH), and Pu VII O 3 (OH)) were calculated at the CCSD(T) level. The first step is the formation of a Lewis acid/base adduct with H 2 O (hydration), followed by a proton transfer to form a dihydroxide molecule (hydrolysis); this process is repeated until all oxo groups are hydrolyzed. The physisorption (hydration) for each H 2 O addition was predicted to be exothermic, ca. -20 kcal/mol. The hydrolysis products are preferred energetically over the hydration products for the +IV and +V oxidation states. The compounds with An VI are a turning point in terms of favoring hydration over hydrolysis. For An VII O 3 (OH), hydration products are preferred, and only two waters can bind; the complete hydrolysis process is now endothermic, and the oxidation state for the An in An(OH) 7 is +VI with two OH groups each having one-half an electron. The natural bond order charges and the reaction energies provide insights into the nature of the hydrolysis/hydration processes. The actinide charges and bond ionicity generally decrease across the period. Here, the ionic character decreases as the oxidation state and coordination number increase so that covalency increases moving to the right in the actinide period.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Synthesis and Characterization of Layered Actinide (U, Np, Pu) Oxide and Hydroxide Phases

Systematic structural comparisons across the early actinides remain limited by the scarcity of well-defined transuranic layered oxide and oxyhydroxide phases. Here, we report the synthesis and single-crystal characterization of new layered actinide compounds spanning U, Np, and Pu obtained under mild hydrothermal conditions in concentrated alkali hydroxide media. These include hydrated oxides α-Cs 2 U 2 O 7 •0.5H 2 O and Rb 2 An 2 O 7 •0.5H 2 O (An = Np, Pu), oxy-hydroxides Rb 6 [(AnO 2 ) 6 O 8 (OH) 2 ]•xH 2 O x = 0, 0.5 (An = U, Np) and Rb 4 [(UO 2 ) 5 O 6 (OH) 2 ]•2H 2 O, as well as nitrate-intercalated compounds Cs 6 [(AnO 2 ) 3 O 4 (OH) 2 ](NO 3 ) 2 (An = Np, Pu). Single-crystal X-ray diffraction studies reveal extended two-dimensional architectures constructed from edge- and vertex-sharing actinyl polyhedra, with systematic evolution in equatorial coordination, hydration, and anionic sheet topology across the U–Np–Pu series. Incorporation of nitrate anions within the interlayer region of Cs 6 [(AnO 2 ) 3 O 4 (OH) 2 ](NO 3 ) 2 establishes a previously unobserved structural motif in layered transuranic oxyhydroxides, demonstrating an additional pathway for anion-mediated framework stabilization. Correlation of crystallographic metrics with single-crystal Raman spectroscopy provides new vibrational benchmarks linking differences in An═O yl bond lengths to the equatorial coordination and the interstitial cations. These findings expand the structural hierarchy of layered actinide materials and address clarifying periodic trends governing topology, bonding, and vibrational signatures in high-valent 5ƒ oxide systems.

actinides↗
DOE OSTI2020

Materials Data on U(SiPt)2 by Materials Project

UPt2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U4+ is bonded in a 8-coordinate geometry to eight equivalent Pt2- atoms. All U–Pt bond lengths are 3.29 Å. Pt2- is bonded to four equivalent U4+ and four equivalent Si atoms to form a mixture of distorted corner, edge, and face-sharing PtU4Si4 tetrahedra. All Pt–Si bond lengths are 2.49 Å. Si is bonded in a 5-coordinate geometry to four equivalent Pt2- and one Si atom. The Si–Si bond length is 2.30 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(NiP)2 by Materials Project

UNi2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U3+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All U–P bond lengths are 2.88 Å. Ni+1.50+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing NiP4 tetrahedra. All Ni–P bond lengths are 2.28 Å. P3- is bonded in a 9-coordinate geometry to four equivalent U3+, four equivalent Ni+1.50+, and one P3- atom. The P–P bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(SiNi)2 by Materials Project

UNi2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All U–Si bond lengths are 3.02 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.31 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent U4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.33 Å.

36 MATERIALS SCIENCE↗