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DOE OSTI2020

Materials Data on Cr(Bi7O12)2 by Materials Project

Bi14CrO24 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share a cornercorner with one BiO7 pentagonal bipyramid. There are a spread of Cr–O bond distances ranging from 1.66–1.68 Å. There are fourteen inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.17–2.94 Å. In the second Bi3+ site, Bi3+ is bonded to five O2- atoms to form distorted corner-sharing BiO5 square pyramids. There are a spread of Bi–O bond distances ranging from 2.13–2.64 Å. In the third Bi3+ site, Bi3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Bi–O bond distances ranging from 2.33–2.83 Å. In the fourth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.15–3.08 Å. In the fifth Bi3+ site, Bi3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.26–3.09 Å. In the sixth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.14–2.98 Å. In the seventh Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.14–3.06 Å. In the eighth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.24–2.84 Å. In the ninth Bi3+ site, Bi3+ is bonded in a 5-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.15–3.09 Å. In the tenth Bi3+ site, Bi3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Bi–O bond distances ranging from 2.33–2.85 Å. In the eleventh Bi3+ site, Bi3+ is bonded to seven O2- atoms to form distorted BiO7 pentagonal bipyramids that share a cornercorner with one BiO5 square pyramid and a cornercorner with one CrO4 tetrahedra. There are a spread of Bi–O bond distances ranging from 2.27–2.82 Å. In the twelfth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.15–2.88 Å. In the thirteenth Bi3+ site, Bi3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.13–2.70 Å. In the fourteenth Bi3+ site, Bi3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.28–2.97 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Cr6+ and two Bi3+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the third O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the fourth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the ninth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the tenth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the thirteenth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the fourteenth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the fifteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Cr6+ and two Bi3+ atoms. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the eighteenth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the nineteenth O2- site, O2- is bonded in a single-bond geometry to one Cr6+ and four Bi3+ atoms. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the twenty-first O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the twenty-second O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the twenty-third O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a single-bond geometry to one Cr6+ and two Bi3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Cr(ClO)2 by Materials Project

CrO2Cl2 is Silicon tetrafluoride-derived structured and crystallizes in the monoclinic P2_1 space group. The structure is zero-dimensional and consists of two CrO2Cl2 clusters. Cr6+ is bonded in a tetrahedral geometry to two O2- and two Cl1- atoms. Both Cr–O bond lengths are 1.59 Å. There are one shorter (2.12 Å) and one longer (2.13 Å) Cr–Cl bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Cr6+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Cr6+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Fuel-cladding chemical interaction of a prototype annular U-10Zr fuel with Fe-12Cr ferritic/martensitic HT-9 cladding

As an alternative fuel form, the annular metallic fuel design eliminates the liquid sodium bond between the fuel and the cladding, providing back-end fuel cycle and other benefits. The fuel-cladding chemical interaction (FCCI) of annular fuel also presents new features. In this work, state-of-the-art electron microscopy and spectroscopy techniques were used to study the FCCI of a prototype annular U-10wt%Zr (U-10Zr) fuel with ferritic/martensitic HT-9 cladding irradiated to 3.3% fission per initial heavy atom. Compared with sodium-bonded solid fuels, negligible amounts of lanthanides were found in the FCCI layer in the investigated helium-bonded annular fuel. Instead, most lanthanides were retained in the newly formed UZr 2 phase in the fuel center region. The interdiffusion of iron and uranium resulted in tetragonal ( U ,Zr) 6 Fe phase (space group I4/mcm) and cubic ( U ,Zr)( Fe ,Cr) 2 phase (space group Fd 3 ¯ m). The ( U ,Zr)( Fe ,Cr) 2 phase contains a high density of voids and intergranular uranium monocarbides of NaCl-type crystal structure (space group Fm 3 ¯ m). At the interdiffusion zone and inner cladding interface, a porous lamellar structure composed of alternating Cr-rich layers and U-rich layers was observed. Next to the lamellar region, the unexpected phase transformation from body-centered cubic ferrite (α-Fe) to tetragonal binary Fe-Cr σ phase (space group P4 2 /mnm) occurred, and tetragonal Fe-Cr-U-Si phase (space group I4/mmm) was identified. Due to the diffusion of carbon into the interdiffusion zone, carbon depletion inside the HT-9 led to the disappearance of the martensite lath structure, and intergranular U-rich carbides formed as a result of the diffusion of uranium into the cladding. These detailed new findings reveal the unique features of the FCCI behavior of annular U-Zr fuels, which could be a promising alternative fuel form for high burnup fast reactor applications.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2025

Unraveling Impurity-Dependent Morphological and Chemical Evolution of Ni–20Cr Alloy in Eutectic LiCl–KCl Molten Salt

Understanding the interfacial evolution of alloys in molten salt with different amounts of water (H 2 O) and oxygen (O 2 ) impurities is significant for applications in many fields, including concentrated solar power, molten salt reactors, and applications in pyrochemical reprocessing and electrorefining. Additionally, the impurity-driven corrosion mechanisms that lead to various morphological and chemical evolution characteristics at the interfaces of structural alloys and molten salts are not fully understood. In the present work, the three-dimensional (3D) morphological evolution of Ni-20Cr microwires in LiCl-KCl was studied at 500 °C under different moisture and oxygen conditions using in situ synchrotron transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) techniques. No significant morphological changes were observed in Ni-20Cr microwires under vacuum conditions. However, the wires exhibited distinct morphological evolutions when exposed to molten salt containing H 2 O alone, as well as when both H 2 O and O 2 were present. Furthermore, Cr 2 O 3 precipitates were observed in the molten salt during corrosion with only H 2 O present, while Cr 6+ species were identified in the salt when O 2 was added. Further, these findings are crucial for understanding the corrosion mechanisms of molten salt with different amounts of H 2 O and O 2 contamination, providing insights for developing corrosion mitigation methods and improving the stability of containment alloys in molten salt applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Computational thermodynamics-guided alloy design and phase stability in CoCrFeMnNi-based medium-and high-entropy alloys: An experimental-theoretical study

A computational thermodynamics approach has been employed to design CoCrFeMnNi-based medium- and high-entropy alloys (M/HEAs) with systematically varied compositions (Co(( 80-X )/ 2 )Cr(( 80-X )/ 2 )Fe X Mn 10 Ni 10 with x = 30, 40, and 50 at.%) and phase stability. Since the formation of sigma phase, usually brittle and undesirable, is a common concern, when this class of alloys is subjected to elevated temperatures (600–1000 °C), predicting its formation becomes essential. Thus, its formation and the phase equilibria were studied using the CALPHAD method, and two empirical methods, namely, valence electron concentration (VEC) and paired sigma-forming element (PSFE). Isothermal aging treatments at 900–1100 °C for 20 h were performed, since CALPHAD and VEC/PSFE predictions diverged. Both prediction methods were compared with experimental characterization by a combination of scanning electron microscopy and high-energy synchrotron X-ray diffraction. In conclusion, the predictions from the VEC/PSFE and CALPHAD calculations (depending on the database used) were shown to be quite accurate.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Electronegative ligands enhance charge transfer to Mn 12 single-molecule magnets deposited on graphene

Combining single-molecule magnets (SMMs) and emergent two-dimensional substrates such as graphene may lead to device configurations that are promising for spintronics and quantum computing. Yet, to fully consider the unique features of SMMs anchored to two-dimensional substrates, the choice of ligand attachments, which could affect the magnetic and electronic properties, is critical. In this work, we focus on hybrid junctions comprising CVD-grown graphene and [Mn 12 O 12 (O 2 CR) 16 (H 2 O) 4 ]( R = CH 3 , CHCl 2 ) SMMs with different ligands. We find that [Mn 12 O 12 (O 2 CCH 3 ) 16 (H 2 O) 4 ] SMMs barely change the graphene’s conductivity, while [Mn 12 O 12 (O 2 CCHCl 2 ) 16 (H 2 O) 4 ] SMMs with more electronegative ligands, by means of charge transfer, remarkably modify the electronic transport in graphene as revealed by gate-voltage dependent magnetotransport measurements.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2022

Structural and electronic properties of rare-earth chromites: A computational and experimental study

Here, in this work, the structural, optical, and electronic properties of rare-earth perovskites of the general formula R⁢ CrO 3 , where R⁢ represents the rare-earth Gd, Tb, Dy, Ho, Er, and Tm, have been studied in detail. These compounds were synthesized through a facile citrate route. X-ray diffraction, Raman spectroscopy, and UV-Visible spectroscopy were utilized to reveal the structural evolutions in R⁢ ⁢CrO 3 . The lattice parameters, Cr 3+ –O 2 –Cr 3+ bond angle, and CrO 6 octahedral distortions were found to strongly depend on the ionic radii of R⁢ . First-principles calculations based on density-functional theory within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) and strongly constrained and appropriately normed (SCAN) meta-GGA were also employed to calculate the structural and electronic properties of R⁢ ⁢CrO 3 . The ground-state energy, lattice constants, electronic structures, and density of states of R⁢ ⁢CrO 3 were calculated. These provide some insights into the electronic characteristics of the R⁢ ⁢CrO 3 compounds. The calculated values of lattice parameters and band gaps with Hubbard U correction (SCAN+ U ) agree well with values measured experimentally and show more accuracy in predicting the ground-state crystal structure and band structure compared to PBE+ U approximation. The band gap of R⁢ ⁢CrO 3 is found to be independent of the ionic radii of R⁢ from both experiments and calculations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2024

Compositional evidence for chondrule origins of low‐Ca pyroxenes in comet Wild 2 and a giant cluster IDP

Abstract A literature compilation of 1136 low‐Ca pyroxene compositions from chondrules from 12 primitive type 2–3 carbonaceous, ordinary and enstatite chondrite groups define unique regions on an Al 2 O 3 and Cr 2 O 3 diagram when compared to low‐Ca pyroxenes from equilibrated type 4‐6 chondrites. Measured compositions of 100 low‐Ca pyroxenes from comet Wild 2 and a giant cluster IDP of probable cometary origin are similar to each other and fall in the type 2–3 chondrite chondrule region suggesting that most of the pyroxenes likely formed in the solar nebula like conventional chondrules. The data imply that most low Ca‐pyroxenes from comet Wild 2 and the giant cluster IDP formed from igneous crystallization processes and did not experience significant thermal metamorphism, indicating that the low‐Ca pyroxenes were unlikely incorporated into large parent bodies prior to accretion in their respective comet bodies. An intriguing group of nine low‐Ca pyroxenes from comet Wild 2 with low Cr and Al that fall where type 4–6 chondrites are located are interpreted as products of condensation. The compositional data combined with previously measured oxygen isotopes on 17 low‐Ca pyroxenes support earlier conclusions that comet samples have links with carbonaceous, ordinary, and possibly enstatite chondrite groups. Our results provide additional evidence that comets accreted materials from multiple chondrule reservoirs throughout the solar nebula.

Geochemistry & Geophysics↗

DOE OSTI2020

Materials Data on Cr(AgO2)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Cr(CoO3)2 by Materials Project

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Cr(Bi7O12)2 by Materials Project

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Cr(CoO3)2 by Materials Project

36 MATERIALS SCIENCE↗

DOE OSTI2023

Characterization of the Sulfur-Saturated Melt Versions of the HLW HAlG Glasses

This report provides the results from the chemical analyses of a series of sulfur-saturated melt versions of the High-Level Waste High-Aluminum Glass study glasses, a series of simulated nuclear waste glasses designed and fabricated at Pacific Northwest National Laboratory. These data will be used in the development, validation, and implementation of enhanced property/composition models for waste glass vitrification at Hanford. Chemical analyses were performed on a representative sample of each of the sulfur-saturated melt versions of the glasses to allow for comparisons with targeted compositions as well as the measured compositions of the quenched glasses. The relative differences between the targeted and measured concentrations of B 2 O 3 , Cr 2 O 3 , K 2 O, Li 2 O, Na 2 O, and P 2 O 5 for several of the glasses were greater than ±10%. The relative differences between the targeted and measured concentrations of Al 2 O 3 and ZrO 2 for one of the glasses were greater than ±10%. As expected, the measured concentrations of SO 3 in most of the glasses were higher than targeted due to the use of the sulfur saturation method in fabricating these glasses. The wash solutions contained mainly sodium, sulfur, and sulfate ions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Termination switching of antiferromagnetic proximity effect in topological insulator

This work reports the ferromagnetism of topological insulator, (Bi,Sb) 2 Te 3 (BST), with a Curie temperature of approximately 120 K induced by magnetic proximity effect (MPE) of an antiferromagnetic CrSe. The MPE was shown to be highly dependent on the stacking order of the heterostructure, as well as the interface symmetry: Growing CrSe on top of BST results in induced ferromagnetism, while growing BST on CrSe yielded no evidence of an MPE. Cr-termination in the former case leads to double-exchange interactions between Cr 3+ surface states and Cr 2+ bulk states. This Cr 3+ -Cr 2+ exchange stabilizes the ferromagnetic order localized at the interface and magnetically polarizes the BST Sb band. In contrast, Se-termination at the CrSe/BST interface yields no detectable MPE. These results directly confirm the MPE in BST films and provide critical insights into the sensitivity of the surface state.

42 ENGINEERING↗

DOE OSTI2021

The Magneto-Transport Properties of Cr 1/3 TaS 2 with Chiral Magnetic Solitons

Cr 1/3 TaS 2 —a candidate of chiral magnet—has been reported as a trivial ferromagnetic material. In contrast, the Cr 1/3 TaS 2 single crystals exhibit a chiral helimagnetic (CHM) transition near 140 K. The magnetic moment versus magnetic field curves reveal a CHM—chiral soliton lattice (CSL)—forced ferromagnetic (FFM) transition in the magnetic ordered state. The conducting electrons interact with the CHM and CSL orders, giving rise to the nontrivial magnetoresistance (MR) in the Cr 1/3 TaS 2 single crystals. The normalized magnetic moment and normalized MR fit well with the analytical functions for chiral soliton density. The magnetic phase diagrams constructed from the magnetic moment data and MR data suggest a possible tri-critical point. Compared with the isostructural Cr 1/3 NbS 2 , the CHM transition temperature of Cr 1/3 TaS 2 is 13 K higher, the CSL—FFM transition field is about 10 times larger, and the Dzyaloshinskii-Moriya interaction strength is 3 times bigger. The latter two likely originate from the strong spin-orbit coupling (SOC) of Cr 1/3 TaS 2 . This work clarifies that high-quality Cr 1/3 TaS 2 single crystals are chiral magnets and Cr 1/3 (Nb,Ta)S 2 could serve as an intriguing platform for the flexible engineering of chiral magnetic solitons with tunable SOC.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Impact on aggregate/matrix bonding when a refractory contains zinc aluminate instead of spinel and magnesia‐chrome

The high hot strength of MgO–Cr 2 O 3 refractory is often ascribed to its intimate aggregate/matrix bonding. For a fundamental comparison with it, ~2 mm aggregates of MgO and Al 2 O 3 were separately embedded in ZnAl 2 O 4 and MgAl 2 O 4 matrices, sintered at 1600°C, and examined. It was found that similarity of thermal expansion coefficient (TEC) between the aggregate and the matrix is critical to achieve good bonding and this is more important than the extent of interdiffusion. The TEC mismatch of ≥ 5.7 × 10 -6 K -1 caused significant undesirable debonding in MgO aggregate/MgAl 2 O 4 matrix sample and MgO/ZnAl 2 O 4 despite >736 μm Zn 2+ diffusion depth in the latter. Direct bonding, as inferred from a thicker interfacial reaction layer and a greater shift of the aggregate/matrix interface before and after firing, was better in MgAl 2 O 4 /ZnAl 2 O 4 combination, followed by tabular Al 2 O 3 /ZnAl 2 O 4 and Al 2 O 3 /MgAl 2 O 4 . Powder X-ray diffraction indicated that the volatilization of ZnAl 2 O 4 at 1600°C in air was negligible compared to MgO–Cr 2 O 3 .

36 MATERIALS SCIENCE↗

DOE OSTI2021

Anomalous Hall effect in the weak-itinerant ferrimagnet FeCr 2 Te 4

In this study, we carried out a comprehensive study of electronic transport, thermal, and thermodynamic properties in Fe Cr 2 Te 4 single crystals. It exhibits bad-metallic behavior and anomalous Hall effect (AHE) below a weak-itinerant paramagnetic-to-ferrimagnetic transition T c ~ 123 K. The linear scaling between the anomalous Hall resistivity ρ x y and the longitudinal resistivity ρ x x implies that the AHE in Fe Cr 2 Te 4 is most likely dominated by an extrinsic skew-scattering mechanism rather than an intrinsic KL or an extrinsic side-jump mechanism, which is supported by our Berry phase calculations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2025

First-Principles study of interface capture of Ni during high-temperature oxidation of NiCr alloys

The formation of precipitated phases of less reactive metals within an oxide scale during alloy oxidation can disrupt its structural integrity, significantly compromising the protective function of the oxide. To better understand this phenomenon, it is crucial to investigate the atomic-level diffusion mechanisms that drive precipitate formation. In this study, we employ first-principles calculations to examine the diffusion and aggregation of Ni atoms across the NiCr/Cr 2 O 3 interface during the high-temperature oxidation of NiCr alloys. Our results reveal that, in the absence of Cr vacancies, Ni atoms predominantly remain within the NiCr substrate, with minimal migration toward the Cr 2 O 3 layer. However, when Cr vacancies are present at both the NiCr/Cr 2 O 3 interface and within the Cr 2 O 3 bulk, Ni atoms exhibit a strong propensity to migrate from the NiCr substrate into the Cr 2 O 3 bulk, where they aggregate into Ni-rich regions with a corundum structure. This study provides valuable atomic-level insights into the diffusion and aggregation of less-reactive metals at the alloy/oxide interface, enhancing our understanding of solute capture and its contribution to the degradation of oxidation resistance in alloys.

Chen, Jianmin [Xiangtan University (China)] (ORCID↗