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DOE OSTI2020

Materials Data on AlV4C3 by Materials Project

V4AlC3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two aluminum molecules and two V4C3 sheets oriented in the (0, 0, 1) direction. In each V4C3 sheet, there are two inequivalent V+2.25+ sites. In the first V+2.25+ site, V+2.25+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All V–C bond lengths are 2.00 Å. In the second V+2.25+ site, V+2.25+ is bonded to six C4- atoms to form a mixture of edge and corner-sharing VC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.08 Å) and three longer (2.10 Å) V–C bond lengths. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to six V+2.25+ atoms to form a mixture of edge and corner-sharing CV6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second C4- site, C4- is bonded to six equivalent V+2.25+ atoms to form a mixture of edge and corner-sharing CV6 octahedra. The corner-sharing octahedral tilt angles are 1°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Li3CuF4 by Materials Project

Li3CuF4 is MAX Phase structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six equivalent F1- atoms to form a mixture of edge and corner-sharing LiF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Li–F bond lengths are 2.04 Å. In the second Li1+ site, Li1+ is bonded to six F1- atoms to form LiF6 octahedra that share corners with three equivalent LiF6 octahedra, corners with three equivalent CuF6 pentagonal pyramids, edges with nine LiF6 octahedra, and edges with three equivalent CuF6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.02 Å) and three longer (2.04 Å) Li–F bond lengths. Cu1+ is bonded to six equivalent F1- atoms to form distorted CuF6 pentagonal pyramids that share corners with six equivalent LiF6 octahedra, edges with six equivalent LiF6 octahedra, and edges with six equivalent CuF6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 9–10°. There are two shorter (2.30 Å) and four longer (2.31 Å) Cu–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to three equivalent Li1+ and three equivalent Cu1+ atoms to form a mixture of edge, face, and corner-sharing FLi3Cu3 octahedra. The corner-sharing octahedra tilt angles range from 1–43°. In the second F1- site, F1- is bonded to six Li1+ atoms to form a mixture of edge and corner-sharing FLi6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Nb4SiC3 by Materials Project

Nb4C3Si is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two silicon molecules and two Nb4C3 sheets oriented in the (0, 0, 1) direction. In each Nb4C3 sheet, there are two inequivalent Nb2+ sites. In the first Nb2+ site, Nb2+ is bonded to six C4- atoms to form a mixture of edge and corner-sharing NbC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.25 Å) and three longer (2.28 Å) Nb–C bond lengths. In the second Nb2+ site, Nb2+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Nb–C bond lengths are 2.20 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to six equivalent Nb2+ atoms to form a mixture of edge and corner-sharing CNb6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second C4- site, C4- is bonded to six Nb2+ atoms to form a mixture of edge and corner-sharing CNb6 octahedra. The corner-sharing octahedral tilt angles are 1°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Nb4AlN3 by Materials Project

Nb4AlN3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Nb sites. In the first Nb site, Nb is bonded to six N atoms to form a mixture of corner and edge-sharing NbN6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.19 Å) and three longer (2.25 Å) Nb–N bond lengths. In the second Nb site, Nb is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent N atoms. All Nb–Al bond lengths are 2.85 Å. All Nb–N bond lengths are 2.20 Å. Al is bonded to six equivalent Nb atoms to form distorted AlNb6 cuboctahedra that share corners with six equivalent NNb6 octahedra, edges with six equivalent AlNb6 cuboctahedra, and edges with six equivalent NNb6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are two inequivalent N sites. In the first N site, N is bonded to six equivalent Nb atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second N site, N is bonded to six Nb atoms to form NNb6 octahedra that share corners with three equivalent AlNb6 cuboctahedra, corners with three equivalent NNb6 octahedra, edges with three equivalent AlNb6 cuboctahedra, and edges with nine NNb6 octahedra. The corner-sharing octahedral tilt angles are 2°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ti4GaC3 by Materials Project

Ti4GaC3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two gallium molecules and two Ti4C3 sheets oriented in the (0, 0, 1) direction. In each Ti4C3 sheet, there are two inequivalent Ti+2.25+ sites. In the first Ti+2.25+ site, Ti+2.25+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Ti–C bond lengths are 2.08 Å. In the second Ti+2.25+ site, Ti+2.25+ is bonded to six C4- atoms to form a mixture of edge and corner-sharing TiC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.15 Å) and three longer (2.23 Å) Ti–C bond lengths. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to six equivalent Ti+2.25+ atoms to form a mixture of edge and corner-sharing CTi6 octahedra. The corner-sharing octahedral tilt angles are 3°. In the second C4- site, C4- is bonded to six Ti+2.25+ atoms to form a mixture of edge and corner-sharing CTi6 octahedra. The corner-sharing octahedral tilt angles are 3°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on AlV4N3 by Materials Project

V4AlN3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent V sites. In the first V site, V is bonded to six N atoms to form a mixture of edge and corner-sharing VN6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.06 Å) and three longer (2.10 Å) V–N bond lengths. In the second V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent N atoms. All V–Al bond lengths are 2.79 Å. All V–N bond lengths are 1.96 Å. Al is bonded to six equivalent V and six equivalent Al atoms to form AlAl6V6 cuboctahedra that share corners with six equivalent AlAl6V6 cuboctahedra, corners with six equivalent NV6 octahedra, edges with six equivalent AlAl6V6 cuboctahedra, edges with six equivalent NV6 octahedra, and faces with six equivalent AlAl6V6 cuboctahedra. The corner-sharing octahedral tilt angles are 22°. All Al–Al bond lengths are 2.94 Å. There are two inequivalent N sites. In the first N site, N is bonded to six equivalent V atoms to form a mixture of edge and corner-sharing NV6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second N site, N is bonded to six V atoms to form NV6 octahedra that share corners with three equivalent AlAl6V6 cuboctahedra, corners with three equivalent NV6 octahedra, edges with three equivalent AlAl6V6 cuboctahedra, and edges with nine NV6 octahedra. The corner-sharing octahedral tilt angles are 2°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ta4AlN3 by Materials Project

Ta4AlN3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded to six N atoms to form a mixture of edge and corner-sharing TaN6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.18 Å) and three longer (2.23 Å) Ta–N bond lengths. In the second Ta site, Ta is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent N atoms. All Ta–Al bond lengths are 2.83 Å. All Ta–N bond lengths are 2.20 Å. Al is bonded in a 12-coordinate geometry to six equivalent Ta atoms. There are two inequivalent N sites. In the first N site, N is bonded to six equivalent Ta atoms to form a mixture of edge and corner-sharing NTa6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second N site, N is bonded to six Ta atoms to form a mixture of edge and corner-sharing NTa6 octahedra. The corner-sharing octahedral tilt angles are 2°.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Current-Activated Reactive Ultrafast Joining (CARUJ)

We have demonstrated Current Activated Reactive Ultrafast Joining (CARUJ) as a novel approach for rapid fabrication of similar and dissimilar materials, such as ceramic-ceramic and ceramic-metal joint assemblies. The CARUJ technology utilizes resistive heating of carbon-based materials to apply localized heat at, (through or around) joint zones at rates of 10 1 -10 2 ˚C/min, enabling joining at time scales considerably shorter (several minutes as opposed to hours) than conventional approaches for similar systems. Herein, we present our findings while evaluating the CARUJ concept. Three methods of heat application were evaluated: (i) using carbon joule heating elements to apply heat directly through the joint interface; (ii) using flexible joule heating elements to locally apply heat around the assembly interface; and (iii) non-contact heating of the joint assembly using inductive power. Schemes (ii) and (iii) proved to be the most effective in producing mechanically sound reliable joints. We demonstrated single-step fabrication of dense SiC-SiC joints with a Si- SiC interface using minimal pressure (1–2 MPa) in under 30 minutes. Measured average joint strengths of about 15 MPa are initially achieved for joined bodies when tested in single lap offset (SLO) compressive shear, while tuning of the interfacial composition along with a reduction in interlayer thickness, results in improved joint strengths of approximately 43 MPa. We further demonstrated SiC-SiC joining using Active Brazing Alloys (ABAs) proof of concept joining of tubular geometries. The versatility of CARUJ is demonstrated by utilizing non-contact heating via induction, to join dissimilar materials systems of SiC, SS316 and MAX phase ceramics with ABA interlayers. The localized and rapid heat application realizes a versatile material joining technique that can be extended for joining components at the plant site.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Multiscale Modeling of Silicon Carbide Cladding for Nuclear Applications: Thermal Performance Modeling

The complex multiscale and anisotropic nature of silicon carbide (SiC) ceramic matrix composite (CMC) makes it difficult to accurately model its performance in nuclear applications. The existing models for nuclear grade composite SiC do not account for the microstructural features and how these features can affect the thermal and structural behavior of the cladding and its anisotropic properties. In addition to the microstructural features, the properties of individual constituents of the composites and fiber tow architecture determine the bulk properties. Models for determining the relationship between the individual constituents’ properties and the bulk properties of SiC composites for nuclear applications are absent, although empirical relationships exist in the literature. Here, a hierarchical multiscale modeling approach was presented to address this challenge. This modular approach addressed this difficulty by dividing the various aspects of the composite material into separate models at different length scales, with the evaluated property from the lower-length-scale model serving as an input to the higher-length-scale model. The multiscale model considered the properties of various individual constituents of the composite material (fiber, matrix, and interphase), the porosity in the matrix, the fiber volume fraction, the composite architecture, the tow thickness, etc. By considering inhomogeneous and anisotropic contributions intrinsically, our bottom-up multiscale modeling strategy is naturally physics-informed, bridging constitutive law from micromechanics to meso-mechanics and structural mechanics. The effects that these various physical attributes and thermo-physical properties have on the composite’s bulk thermal properties were easily evaluated and demonstrated through the various analyses presented herein. Since silicon carbide fiber-reinforced SiC CMCs are also promising thermal–structural materials with a broad range of high-end technology applications beyond nuclear applications, we envision that the multiscale modeling method we present here may prove helpful in future efforts to develop and construct reinforced CMCs and other advanced composite nuclear materials, such as MAX phase materials, that can service under harsh environments of ultrahigh temperatures, oxidation, corrosion, and/or irradiation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2022

Recent Advances and Prospects in Design of Hydrogen Permeation Barrier Materials for Energy Applications—A Review

The hydrogen infrastructure involves hydrogen production, storage and delivery for utilization with clean energy applications. Hydrogen ingress into structural materials can be detrimental due to corrosion and embrittlement. To enable safe operation in applications that need protection from hydrogen isotopes, this review article summarizes most recent advances in materials design and performance characterization of barrier coatings to prevent hydrogen isotopes’ absorption ingress and permeation. Barriers are crucial to prevent hydride formation and unwanted hydrogen effects to increase safety, materials’ lifetime and reduce cost for applications within nuclear and renewable energy. The coating may be applied on a material that requires protection from hydrogen pick-up, transport and hydride formation in hydrogen storage containers, in pipelines, spent nuclear fuel storage or in nuclear reactors. While existing, commercial coatings that have been much in use may be satisfactory for various applications, it is desirable to evaluate whether alternative coating concepts can provide a greater resistance to hydrogen isotope permeation along with other improved properties, such as mechanical strength and thermal resistance. The information presented here is focusing on recent findings within the past 5–7 years of promising hydrogen barriers including oxides, nitrides, carbon, carbide, MAX-phases and metals and their mechanical strength, hydrogen pick-up, radiation resistance and coating manufacturing techniques. A brief introduction to hydrogen permeation is provided. Knowledge gaps were identified to provide guidance for material’s research prospects.

08 HYDROGEN↗

DOE OSTI2023

Tuning MXene Surface Terminations for Strategic Control of Physical Properties

Scientific Achievement • Ti3C2Tx surfaces with a higher hydroxyl group concentration play a pivotal role in surface properties and were found to be thermodynamically stable. • From the electronic bonding analysis, the charge density difference and electron localization function demonstrated a significant electron localization at the hydroxyl group, which results in a locally induced dipole on the surface. • A large tunability in the work function is found from different concentrations of functional groups on the surface which can be controlled by the concentration of HF used for etching of the MAX phase to produce the resulting MXene. Research Details • The influence of termination group distribution on the surface of Ti3C2Tx MXenes from various etching concentrations of HF was evaluated • The work functions of Ti3C2Tx MXenes with differing concentrations of functional groups were determined • The influence of termination group clustering on the surface of Ti3C2Tx MXenes was investigated by visualization of the electron localization function and charge density difference

Ward, Patrick A.↗

DOE OSTI2025

Impact of Synthesis and Aging on Titanium Carbide MXenes for Printed Microsystems

This work investigates the long-term electrical stability of Ti3C2Tx MXene Inks under accelerated aging conditions. Inks were synthesized from commercial MAX-Phase precursors, drop-cast onto custom PCB’s and monitored automated in-situ measurements. Samples aged at 85°C/85% RH, 85°C/0% RH and ambient conditions revealed distinct degradation trends. Wet aged inks showed rapid resistance increased while etched formulations exhibited long term stability. These findings highlight the influence of synthesis stage and environmental exposure on MXene Inks reliability, offering critical insights for printed MEMS and sensor applications. Ongoing measurements extend the aging timeline beyond prior studies, marking the longest evaluation under accelerated aging conditions to date.

Aging↗

DOE OSTI2022

Magnetic phase diagram of (Mo 2/3 RE 1/3 ) 2 AlC, RE = Tb and Dy, studied by magnetization, specific heat, and neutron diffraction analysis

We report the results of magnetization, heat capacity, and neutron diffraction measurements on (Mo 2/3 RE 1/3 ) 2 AlC with RE = Dy and Tb. Temperature and field-dependent magnetization as well as heat capacity were measured on a powder sample and on a single crystal allowing the construction of the magnetic field-temperature phase diagram. To study the magnetic structure of each magnetic phase, we applied neutron diffraction in a magnetic field up to 6 T. For (Mo 2/3 Dy 1/3 ) 2 AlC in zero field, a spin density wave is stabilized at 16 K, with antiferromagnetic ordering at 13 K. Furthermore, we identify the coexistence of ferromagnetic and antiferromagnetic phases induced by magnetic fields for both RE = Tb and Dy. The origin of the field induced phases is resulting from the competing ferromagnetic and antiferromagnetic interactions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2023

Growth of titania and tin oxide from Ti 2 SnC via rapid thermal oxidation in air for lithium-ion battery application

Herein, we report the synthesis of TiO 2 –SnO 2 –C/carbide hybrid electrode materials for Li-ion batteries (LIBs) via two different methods of controlled oxidation of layered Ti 2 SnC. The material was partially oxidized in an open-air furnace (OAF) or using a rapid thermal annealing (RTA) approach to obtain the desired TiO 2 –SnO 2 –C/carbide hybrid material; the carbide phase encompassed both residual Ti 2 SnC and TiC as a reaction product. We tested the oxidized materials as an anode in a half cell to investigate their electrochemical performance in LIBs. Analysis of the various oxidation conditions indicated the highest initial lithiation capacity of 838 mAh/g at 100 mA/g for the sample oxidized in the OAF at 700°C for 1 h. Still, the delithiation capacity dropped to 427 mAh/g and faded over cycling. Long-term cycling demonstrated that the RTA sample treated at 800°C for 30 s was the most efficient, as it demonstrated a reversible capacity of around 270 mAh/g after 150 cycles, as well as a specific capacity of about 150 mAh/g under high cycling rate (2000 mA/g). Given the materials’ promising performance, this processing method could likely be applied to many other members of the MAX family, with a wide range of energy storage applications.

25 ENERGY STORAGE↗

DOE OSTI2025

A New Family of Ternary Intermetallic Compounds with Dualistic Atomic Ordering – The ZIP Phases

A new family of nanostructured ternary intermetallic compounds − named the ZIP phases − is introduced in this work. The ZIP phases exhibit dualistic atomic ordering, i.e., they form two structural variants: one with the fcc diamond cubic structure (space group Fd$\bar{3}$m) and one with the hexagonal structure (space group P6 3 /mmc). They are also characterized by metallic behavior, ionic bonding, and atomic zigzagging. Powder metallurgical routes involving pressure-assisted densification are adopted to demonstrate ZIP phase synthesis in the Nb-Si-Ni, Nb-Si-Co, Ta-Si-Ni, V-Si-Ni, and Nb-Si-Fe ternary systems. Crucially, reactive hot pressing is capable of producing high-purity ZIP phase materials after the judicious, elemental system-specific optimization of the processing route. Synthesis of phase-pure materials – demonstrated in the Nb-Si-Ni ternary system by the synthesis of quasi phase-pure Nb 3 SiNi 2 and Ni 3 SiNb 2 ZIP phase-based materials – is a steppingstone to the prospective exploitation of the ZIP phases. Characterization of Nb 3 SiNi 2 and Ni 3 SiNb 2 involves crystal structure determination, spatially resolved chemical analysis, and determination of select thermal, electrical, magnetic, mechanical, and physical properties. Density functional theory is used to assess the stability of Nb 3 SiNi 2 & Ni 3 SiNb 2 and derivative binary compounds at different temperatures, also exploring the exfoliation of these two ZIP phases along specific surfaces to produce 2D derivatives.

Intermetallic compounds (IMCs)↗

DOE OSTI2020

Helium effects and bubbles formation in irradiated Ti 3 SiC 2

Ti 3 SiC 2 is a potential structural material for nuclear reactor applications. However, He irradiation effects in this material are not well understood, especially at high temperatures. Here, we compare the effects of He irradiation in Ti 3 SiC 2 at room temperature (RT) and at 750 °C. Irradiation at 750 °C was found to lead to extremely elongated He bubbles that are concentrated in the nano-laminate layers of Ti 3 SiC 2 , whereas the overall crystal structure of the material remained intact. In contrast, at RT, the layered structure was significantly damaged and highly disordered after irradiation. Our study reveals that at elevated temperatures, the unique structure of Ti 3 SiC 2 can accommodate large amounts of He atoms in the nano-laminate layer, without compromising the structural stability of the material. The structure and the mechanical tests results show that the irradiation induced swelling and hardening at 750 °C are much smaller than those at RT. Overall, these results indicate that Ti 3 SiC 2 has an excellent resistance to accumulation of radiation-induced He impurities and that it has a considerable tolerance to irradiation-induced degradation of mechanical properties at high temperatures.

36 MATERIALS SCIENCE↗

DOE OSTI2025

MXene-Derived Potassium-Preintercalated Bilayered Vanadium Oxide Nanostructures for Cathodes in Nonaqueous K-Ion Batteries

Bilayered vanadium oxides (BVOs) are promising cathode materials for beyond-Li-ion batteries due to their tunable chemistries and high theoretical capacities. However, the large size of beyond-Li + ions limits electrochemical cycling and rate capability of BVO electrodes. Recent reports of MXene-derived BVOs with nanoscale flower-like morphology have shown improved electrochemical stability at high rates up to 5C in nonaqueous lithium-ion batteries. Here, we report how morphological stabilization can lead to improved rate capability in potassium-ion batteries (PIBs) through the synthesis and electrochemical characterization of MXene-derived K-preintercalated BVOs (MD-KVOs), which were derived from two V 2 CT x precursor materials prepared using two different etching protocols. We show that the etching conditions affect the surface chemistry of the MXene, which plays a role in the MXene-to-oxide transformation process. MXene derived from a milder etchant transformed into a nanoflower MD-KVO with two-dimensional (2D) nanosheet petals (KVO-DMAE) while a more aggressive etchant produced a MXene that transformed into a MD-KVO with one-dimensional (1D) nanorod morphology (KVO-CMAE). Electrochemical cycling of the produced MD-KVOs after drying at 200 °C under vacuum (KVO-DMAE-200 and KVO-CMAE-200) in PIBs showed that electrochemical stability of MD-KVO at high rates improved through the morphological stabilization of 2D particles combined with the control of interlayer water and K + ion content. Structure refinement of KVO-DMAE-200 further corroborates the behavior observed during K + ion cycling, connecting structural and compositional characteristics to the improved rate capability. This work demonstrates how proper synthetic methodology can cause downstream effects in the control of structure, chemical composition, and morphology of nanostructured layered oxide materials, which is necessary for development of future materials for beyond-Li-ion battery technologies.

25 ENERGY STORAGE↗

DOE OSTI2020

Materials Data on ScTe by Materials Project

ScTe is Molybdenum Carbide MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc2+ is bonded to six equivalent Te2- atoms to form a mixture of corner, edge, and face-sharing ScTe6 octahedra. The corner-sharing octahedral tilt angles are 48°. All Sc–Te bond lengths are 2.96 Å. Te2- is bonded to six equivalent Sc2+ atoms to form a mixture of distorted corner and edge-sharing TeSc6 pentagonal pyramids.

36 MATERIALS SCIENCE↗