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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Influence of Rare Earth Ce Additions on Microstructure and Mechanical Properties of Experimental Pipeline Steels

Herein, the effect of Ce additions ranging from 57 to 263 ppm is evaluated for an experimental pipeline steel. Compared to the Ce-free steel, progressive Ce additions result in a slightly refined microstructure, significantly improve transverse impact properties, and slightly increase strength. All these observations can be attributed to the gradual transformation of Mn sulfide and Mn–Si–Al oxide inclusions to Ce-containing oxide/sulfides. In particular, the inclusions consist exclusively of sub-5 μm spherical Ce 2 O 2 S particles upon near-stoichiometric additions of Ce, considering the oxygen and sulfur impurity level of the steel. In conclusion, the results suggest that Ce is a potentially promising alloying addition for next-generation pipeline steels by replacing overtly deleterious inclusions with potentially beneficial ones.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Microstructural refinement of an Al-Ce-Mg alloy via Shear Assisted Processing and Extrusion

Al-Ce alloys have attracted recent interest because of their high thermal stability due to the low solubility of Ce in the Al matrix. The Al 11 Ce 3 eutectic phase gives excellent strain hardening behavior and moderate high-temperature strength in the as-cast state. However, its strengthening effect is limited by its coarse as-cast structure. Therefore, alternative manufacturing methods such as additive manufacturing or equal channel angular pressing have been applied to refine the Al 11 Ce 3 phase to good effect. However, these techniques are both expensive and time-consuming. Therefore, this study aims to use Shear Assisted Processing and Extrusion (ShAPE), an emerging solid phase processing technique that is more easily scalable than the previously mentioned methods. ShAPE can produce useful cross-sections of an Al-8Ce-4Mg alloy while refining the Al 11 Ce 3 phase to produce a higher strength material. It was found that a low temperature ShAPE process can improve the room temperature yield strength by ~60 % compared to a binary Al-4Mg alloy. Additionally, the high-temperature yield strength of the Al-Ce alloys increased by 20%, with a simultaneous 15% improvement in ductility compared to the binary Al-Mg alloy. Finally, these results highlight the potential for ShAPE as a processing technique for Al-Ce alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Metal–Oxo Cluster Formation Using Ammonium and Sulfate to Differentiate M IV (Th, U, Ce) Chemistries

Isolating isostructural compounds of tetravalent metals M IV (Zr, Hf, Ce, Th, U, Pu, Np) improves our understanding of metal hydrolysis and coordination behavior across the periodic table. These metals form polynuclear clusters typified by the hexamer [M IV 6 O 4 (OH) 4 ] 12+ . Exploiting the ammonium M IV -sulfate (Ce IV , Th IV , and U IV ) phase space targeting rapid crystallization, we isolate the common hexamer [M IV 6 (OH) 4 (O) 4 ] 12+ but with different numbers of capping sulfates and water molecules for Ce IV , Th IV , and U IV . Furthermore, these phases allowed a direct comparison of bonding trends across the series. Upon cocrystallization with the hexamers, higher complex structures can be identified. Thorium features assemblies with monomer-linked hexamer chains. Uranium features assemblies with sulfate-bridged hexamers and the supramolecular assembly of 14 hexamers into the U 84 , [U 6 (OH) 4 (O) 4 ) 14 (SO 4 ) 120 (H 2 O) 42 ] 72– . Last, cerium showcases the isolation from monomers to the Ce 62 , [Ce 62 (OH) 30 (O) 58 (SO 4 ) 71 (H 2 O) 33.25 ] 41– . Furthermore, small-angle X-ray scattering (room temperature) shows ammonium-induced cluster assembly for Ce IV but minimal reactivity for U IV and Th IV . In this study, because the phases crystallized at elevated temperature demonstrates favorable cluster assembly, these solution phase results were surprising and suggest some other characteristics such as Ce’s facile redox behavior, contributes to its solution-phase speciation.

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

Anisotropic magnetism and Kondo-lattice behavior in the frustrated antiferromagnet Ce 3 ⁢MgBi 5

Here, we report the synthesis and physical characterization of single-crystalline Ce 3 ⁢MgBi 5 , a previously unexplored member of the Ce 3 ⁢𝑀⁢𝑃⁢𝑛 5 family. This compound crystallizes in the hexagonal 𝑃⁢6 3 /𝑚⁢𝑐⁢𝑚 structure, featuring an anisotropic Ce sublattice composed of zigzag chains along the 𝑐 axis and a distorted kagome-like network in the basal plane. Magnetization measurements reveal antiferromagnetic order below 𝑇 𝑁 ≈ 4.2K with strong magnetic anisotropy and multiple field-induced metamagnetic transitions for fields applied perpendicular to [001], leading to a dome-shaped 𝐻–𝑇 phase diagram. Electrical transport exhibits characteristic signatures of a Ce-based Kondo lattice, including broad resistivity maxima and pronounced field-dependent anomalies in the magnetoresistance and Hall response that track the magnetic phase boundaries. Specific-heat measurements confirm the magnetic transition and show that the full R ⁢ln⁡ 2 entropy expected for a Ce 3+ Kramers doublet is recovered by 20 K, indicating an extended temperature range of magnetic fluctuations consistent with Kondo correlations. Our results establish Ce 3 ⁢MgBi 5 as a platform within the Ce 3 ⁢𝑀⁢𝑃⁢𝑛 5 family for exploring the interplay of geometric frustration, magnetic anisotropy, and Kondo-lattice physics under applied magnetic fields.

Kondo effect↗
DOE OSTI2023

$μ$ $\mathrm{SR}$ study of the dipole-octupole quantum spin ice candidate $\mathrm{Ce_2Zr_2O_7}$

The Ce 3+ pseudospin-1/2 degrees of freedom in Ce 2 Zr 2 O 7 possess both dipolar and octupolar character which enables the possibility of novel quantum spin liquid ground states in this material. In this study, we report muon spin relaxation and rotation (μSR) measurements on single-crystal samples of Ce 2 Zr 2 O 7 in zero magnetic field and in magnetic fields directed along the [1, $\overline{1}$, 0] and [1, 1, 1] crystallographic directions, and for magnetic fields directed both longitudinal and transverse to the direction of muon polarization. Our zero-field results show no signs of magnetic ordering or spin freezing, consistent with earlier zero-field μSR measurements on a powder sample of Ce 2 Zr 2 O 7 , and also with the expectations for a quantum spin ice. However, we measure a more gentle relaxation rate for Ce 2 Zr 2 O 7 in zero field at low temperatures than was previously reported. This difference in relaxation rate is likely due to the low oxidation and, correspondingly, the high stoichiometry of our singlecrystal samples. Longitudinal field measurements confirm that the magnetic dipole moments in Ce 2 Zr 2 O 7 remain dynamic at T = 0.1 K on the microsecond timescale. For both [1, $\overline{1}$, 0] and [1, 1, 1] magnetic fields, our μSR Knight shift measurements show a field-induced leveling off of the magnetic susceptibility at low temperature which is qualitatively consistent with corresponding calculations using the numerical-linked-cluster method in combination with recent estimates for the nearest-neighbor exchange parameters of Ce 2 Zr 2 O 7 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Dipolar Spin Ice Regime Proximate to an All-In-All-Out Néel Ground State in the Dipolar-Octupolar Pyrochlore Ce 2 Sn 2 O 7

The dipolar-octupolar (DO) pyrochlores, R 2 M 2 O 7 ( R = Ce , Sm , Nd ), are key players in the search for realizable novel quantum spin liquid (QSL) states as a large parameter space within the DO pyrochlore phase diagram is theorized to host QSL states of both dipolar and octupolar nature. New single crystals and powders of Ce 2 Sn 2 O 7 , synthesized by hydrothermal techniques, present an opportunity for a new characterization of the exchange parameters in Ce 2 Sn 2 O 7 using the near-neighbor X Y Z model Hamiltonian associated with DO pyrochlores. Utilizing quantum numerical linked cluster expansion fits to heat capacity and magnetic susceptibility measurements, and classical Monte Carlo calculations to the diffuse neutron diffraction of the new hydrothermally grown Ce 2 Sn 2 O 7 samples, we place Ce 2 Sn 2 O 7 ’s ground state within the ordered dipolar all-in-all-out (AIAO) Néel phase, with quantum Monte Carlo calculations showing a transition to long-range order at temperatures below those accessed experimentally. Indeed, our new neutron diffraction measurements on the hydrothermally grown Ce 2 Sn 2 O 7 powders show a broad signal at low scattering wave vectors, reminiscent of a spin ice, in striking contrast from previous powder neutron diffraction on samples grown from solid-state synthesis, which found diffuse scattering at high scattering wave vectors associated with magnetic and suggested an octupolar quantum spin ice state. We conclude that new hydrothermally grown Ce 2 Sn 2 O 7 samples host a finite-temperature proximate dipolar spin ice phase, above the expected transition to AIAO Néel order. Published by the American Physical Society 2024

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

R-matrix Resolved Resonance Region Evaluation of 140,142 Ce

Oak Ridge National Laboratory completed the resolved resonance region (RRR) evaluation of the two most abundant cerium isotopes, 140 Ce (88.45%) and 142 Ce (11.11%), as requested by the US Nuclear Criticality Safety Program. These evaluations are based on recent high-resolution transmission and capture measurements performed on nat Ce and highly enriched 142 Ce samples at the JRC-Geel Linear Accelerator facility, as well as measured thermal constants available from the EXFOR database. Starting from the resonance parameters of the ENDF/B-VIII.0 library followed by a preliminary R-matrix analysis, an updated set of resonance parameters and corresponding covariance information were derived by fitting these measured data using the Reich–Moore approximation of the R -matrix theory, as implemented in the SAMMY code system. The 140 Ce RRR upper energy limit was kept at 200 keV, whereas the 142 Ce resonance region was extended from 13 to 26 keV. Updated statistical properties were obtained for the new evaluations and compared to those derived from the ENDF/B-VIII.0 nuclear data library. The new evaluation work improved some of the discrepancies found in previous work, such as the capture resonance integral and stellar Maxwellian-averaged cross sections. These integral quantities were mainly derived from the fit of the latest measured data, especially the neutron capture yield data for 142 Ce isotope.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on Ce(Al2Fe)4 by Materials Project

CeFe4Al8 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight equivalent Fe and twelve Al atoms. All Ce–Fe bond lengths are 3.34 Å. There are four shorter (3.00 Å) and eight longer (3.17 Å) Ce–Al bond lengths. Fe is bonded to two equivalent Ce, two equivalent Fe, and eight Al atoms to form a mixture of distorted edge, face, and corner-sharing FeCe2Al8Fe2 cuboctahedra. Both Fe–Fe bond lengths are 2.51 Å. There are four shorter (2.54 Å) and four longer (2.65 Å) Fe–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Ce, four equivalent Fe, and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.73–2.80 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ce, four equivalent Fe, and six Al atoms. Both Al–Al bond lengths are 2.75 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(MnAl2)4 by Materials Project

CeMn4Al8 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight equivalent Mn and twelve Al atoms. All Ce–Mn bond lengths are 3.38 Å. There are four shorter (3.01 Å) and eight longer (3.27 Å) Ce–Al bond lengths. Mn is bonded to two equivalent Ce, two equivalent Mn, and eight Al atoms to form distorted MnCe2Mn2Al8 cuboctahedra that share corners with eight equivalent AlCe2Mn4Al6 cuboctahedra, corners with ten equivalent MnCe2Mn2Al8 cuboctahedra, edges with four equivalent MnCe2Mn2Al8 cuboctahedra, edges with four equivalent AlCe2Mn4Al6 cuboctahedra, faces with six equivalent MnCe2Mn2Al8 cuboctahedra, and faces with eight equivalent AlCe2Mn4Al6 cuboctahedra. Both Mn–Mn bond lengths are 2.58 Å. There are four shorter (2.57 Å) and four longer (2.68 Å) Mn–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Ce, four equivalent Mn, and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.78–2.83 Å. In the second Al site, Al is bonded to two equivalent Ce, four equivalent Mn, and six Al atoms to form distorted AlCe2Mn4Al6 cuboctahedra that share corners with eight equivalent MnCe2Mn2Al8 cuboctahedra, corners with ten equivalent AlCe2Mn4Al6 cuboctahedra, edges with three equivalent AlCe2Mn4Al6 cuboctahedra, edges with four equivalent MnCe2Mn2Al8 cuboctahedra, faces with seven equivalent AlCe2Mn4Al6 cuboctahedra, and faces with eight equivalent MnCe2Mn2Al8 cuboctahedra. Both Al–Al bond lengths are 2.82 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Al2Cu)4 by Materials Project

Al8Cu4Ce crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight equivalent Cu and twelve Al atoms. All Ce–Cu bond lengths are 3.39 Å. There are four shorter (3.09 Å) and eight longer (3.22 Å) Ce–Al bond lengths. Cu is bonded to two equivalent Ce, two equivalent Cu, and eight Al atoms to form a mixture of distorted face, edge, and corner-sharing CuCe2Al8Cu2 cuboctahedra. Both Cu–Cu bond lengths are 2.56 Å. There are four shorter (2.58 Å) and four longer (2.71 Å) Cu–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Ce, four equivalent Cu, and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.70–2.83 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ce, four equivalent Cu, and six Al atoms. Both Al–Al bond lengths are 2.76 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(GePt)2 by Materials Project

Ce(PtGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight equivalent Pt and eight equivalent Ge atoms. All Ce–Pt bond lengths are 3.33 Å. All Ce–Ge bond lengths are 3.35 Å. Pt is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Ge atoms. All Pt–Ge bond lengths are 2.53 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ce, four equivalent Pt, and one Ge atom. The Ge–Ge bond length is 2.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Sn3Ru2)2 by Materials Project

CeRu4Sn6 crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to four equivalent Ru and twelve Sn atoms. All Ce–Ru bond lengths are 3.27 Å. There are a spread of Ce–Sn bond distances ranging from 3.38–3.78 Å. Ru is bonded in a 7-coordinate geometry to one Ce and six Sn atoms. There are a spread of Ru–Sn bond distances ranging from 2.61–2.78 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 6-coordinate geometry to two equivalent Ce and four equivalent Ru atoms. In the second Sn site, Sn is bonded in a 5-coordinate geometry to two equivalent Ce and four equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Ni2Sn)2 by Materials Project

Ce(Ni2Sn)2 crystallizes in the tetragonal I-4c2 space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight equivalent Ni and eight equivalent Sn atoms. There are four shorter (2.75 Å) and four longer (2.88 Å) Ce–Ni bond lengths. All Ce–Sn bond lengths are 3.28 Å. Ni is bonded in a 10-coordinate geometry to two equivalent Ce, four equivalent Ni, and four equivalent Sn atoms. There are two shorter (2.38 Å) and two longer (2.52 Å) Ni–Ni bond lengths. There are a spread of Ni–Sn bond distances ranging from 2.39–2.53 Å. Sn is bonded in a 12-coordinate geometry to four equivalent Ce and eight equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Ni2Sn)2 by Materials Project

Ce(Ni2Sn)2 crystallizes in the tetragonal I-4c2 space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight equivalent Ni and eight equivalent Sn atoms. There are four shorter (3.00 Å) and four longer (3.04 Å) Ce–Ni bond lengths. All Ce–Sn bond lengths are 3.50 Å. Ni is bonded in a 10-coordinate geometry to two equivalent Ce, four equivalent Ni, and four equivalent Sn atoms. There are a spread of Ni–Ni bond distances ranging from 2.53–2.73 Å. There are a spread of Ni–Sn bond distances ranging from 2.54–2.68 Å. Sn is bonded in a 12-coordinate geometry to four equivalent Ce and eight equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(AsPd)2 by Materials Project

Ce(PdAs)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight equivalent Pd and eight equivalent As atoms. All Ce–Pd bond lengths are 3.43 Å. All Ce–As bond lengths are 3.24 Å. Pd is bonded to four equivalent Ce, four equivalent Pd, and four equivalent As atoms to form a mixture of distorted corner, edge, and face-sharing PdCe4As4Pd4 cuboctahedra. All Pd–Pd bond lengths are 2.99 Å. All Pd–As bond lengths are 2.56 Å. As is bonded in a 9-coordinate geometry to four equivalent Ce, four equivalent Pd, and one As atom. The As–As bond length is 2.53 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(PRu)2 by Materials Project

Ce(RuP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight equivalent Ru and eight equivalent P atoms. All Ce–Ru bond lengths are 3.18 Å. All Ce–P bond lengths are 3.14 Å. Ru is bonded in a 12-coordinate geometry to four equivalent Ce and four equivalent P atoms. All Ru–P bond lengths are 2.37 Å. P is bonded in a 9-coordinate geometry to four equivalent Ce, four equivalent Ru, and one P atom. The P–P bond length is 2.48 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(ClO4)3 by Materials Project

Ce(ClO4)3 crystallizes in the trigonal R3c space group. The structure is three-dimensional. Ce is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ce–O bond distances ranging from 2.48–2.58 Å. There are four inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one Ce and one Cl atom. The O–Cl bond length is 1.48 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Ce and one Cl atom. The O–Cl bond length is 1.47 Å. In the third O site, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.42 Å. In the fourth O site, O is bonded in a water-like geometry to one Ce and one Cl atom. The O–Cl bond length is 1.48 Å. Cl is bonded in a tetrahedral geometry to four O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Sn2Pd)2 by Materials Project

CePd2Sn4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to four equivalent Pd and ten Sn atoms. All Ce–Pd bond lengths are 3.53 Å. There are a spread of Ce–Sn bond distances ranging from 3.40–3.55 Å. Pd is bonded in a 6-coordinate geometry to two equivalent Ce and six Sn atoms. There are a spread of Pd–Sn bond distances ranging from 2.74–2.82 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Ce, two equivalent Pd, and two Sn atoms. There are one shorter (2.87 Å) and one longer (3.03 Å) Sn–Sn bond lengths. In the second Sn site, Sn is bonded in a 6-coordinate geometry to one Ce, four equivalent Pd, and one Sn atom.

36 MATERIALS SCIENCE↗