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DOE OSTI2024

Synthesis, microstructure and micro-mechanical characterization of metal (Nb, Ti) – MAX phase (Ti 2 AlC) nanolaminates

We utilize elevated temperature physical vapor deposition (PVD) techniques to design metal/MAX multilayered nanocomposite thin films with alternating nanoscale metallic (Nb, Ti) and MAX phase (Ti 2 AlC) layer thicknesses. These metal/MAX nanolaminate architectures attempt to exploit a unique hierarchical topology – as interfaces between the layers are expected to be in direct competition with the internal interfaces within the MAX layers, to drive their tunable macroscopic mechanical behavior. Two metal/MAX nanolaminates – Nb/Ti 2 AlC and Ti/Ti 2 AlC – were deposited. The Nb/Ti 2 AlC metal/MAX system showed highly diffused layer interfaces with distinct Ti – rich and Nb–Al – rich layers, with the presence of MAX phase alongside TiC and other Ti–Al and Nb–Al intermetallic phases. The Nb/Ti 2 AlC system possessed a layered architecture, though the MAX phases were not found to be continuously present in each alternating layer. The second Ti/Ti 2 AlC system showed a non-lamellar nanocomposite microstructure and the formation of mixed Ti n+1 AlC n phases (a mix of n = 1, 2), and no indication of layering. Diffusion occurring between the metal/MAX layers in both cases, likely due to the elevated temperatures during the deposition process, is speculated as the likely cause of these resultant microstructures. The mechanical properties of both systems were evaluated using micromechanical (nanoindentation and micro-pillar compression) techniques, which demonstrated high strengths for both systems (Nb system: yield and instability strengths of 4.88 ± 0.1 GPa and 5.57 ± 0.03 GPa, Ti system: yield and instability strength of 5.61 ± 0.28 GPa and 6.21 ± 0.25 GPa). In conclusion, this work highlights the promising mechanical properties of metal/MAX multilayered depositions and summarizes the challenges in PVD synthesis of metal/MAX multilayered nanolaminates.

MAX phase↗

DOE OSTI2026

Quaternary i-MAX Phases (Mo 2/3 RE 1/3 ) 2 AlC (RE: Dy, Tb, Er): Experimental Characterization and First-Principles Insights into their Fundamental Properties

Rare earth (RE)-based materials have unique electronic, magnetic, and optical properties, leading to the recent discovery of atomically layered solids with the chemical formula (M' 2/3 RE 1/3 ) 2 AlC, which have since garnered significant attention in the scientific community. This study aims to synthesize, characterize, and investigate the structural and thermal stability of the RE i-MAX phases. We prepared i-MAX phases using molybdenum (Mo) as M′ and RE elements as Dy, Tb, and Er, namely (Mo 2/3 Dy 1/3 ) 2 AlC, (Mo 2/3 Tb 1/3 ) 2 AlC, and (Mo 2/3 Er 1/3 ) 2 AlC. Structural characterization through x-ray diffraction (XRD) and Raman spectroscopy confirms the formation of the RE-based i-MAX phase, along with the presence of minor impurity phases in the alloys. Thermogravimetric analysis (TGA) conducted up to 1000°C under ambient conditions reveals that the i-MAX phases remain thermally stable up to approximately 450°C, beyond which oxidation leads to a noticeable weight gain in all samples. Differential scanning calorimetry (DSC) measurements during heating and cooling cycles show endothermic and exothermic peaks for (Mo 2/3 Dy 1/3 ) 2 AlC i-MAX in the 410–420°C range, indicating a temperature-induced minor atomic arrangement. In contrast, these peaks are absent in the Tb- and Er-based i-MAX phases. These findings offer valuable insights into the thermal behavior and stability of these i-MAX phases under thermal stress, contributing to a deeper understanding of their unique properties. Furthermore, first-principles density functional theory (DFT) calculations were performed to investigate the electronic and optical properties of the i-MAX phases. The results reveal their metallic nature, with pronounced contributions from Mo and RE elements near the Fermi level and within the conduction band.

Rare earth↗

DOE OSTI2021

Measurement report: Cloud condensation nuclei activity and its variation with organic oxidation level and volatility observed during an aerosol life cycle intensive operational period (ALC-IOP)

Abstract. Cloud condensation nuclei (CCN) spectrum and the CCN activated fraction of size-resolved aerosols (SR-CCN) were measured at a rural site on Long Island during the Department of Energy (DOE) aerosol life cycle intensive operational period (ALC-IOP) from 15 July to 15 August 2011. During the last week of the ALC-IOP, the dependence of the activated fraction on aerosol volatility was characterized by sampling downstream of a thermodenuder (TD) operated at temperatures up to 100 ∘C. Here we present aerosol properties, including aerosol total number concentration, CCN spectrum, and the CCN hygroscopicity, for air masses of representative origins during the ALC-IOP. The hygroscopicity of organic species in the aerosol is derived from CCN hygroscopicity and chemical composition. The dependence of organic hygroscopicity on the organic oxidation level (e.g., atomic O:C ratio) agrees well with theoretical predictions and results from previous laboratory and field studies. The derived κorg and O:C ratio first increase as TD temperature increases from 20 ∘C (i.e., ambient temperature) to 50 or 75 ∘C and then decrease as TD temperature further increases to 100 ∘C. The initial increases of O:C and κorg with TD temperature below 50 ∘C are likely due to evaporation of more volatile organics with relatively lower O:C and hygroscopicity such as primary organic aerosol. At the high TD temperatures, the decreases of O:C and κorg indicate that evaporated organics were more oxygenated and had lower molecular weights. These trends are different from previous laboratory experiments and field observations, which reported that organic O:C increased monotonically with increasing TD temperature, whereas κorg decreased with the TD temperature. One possible reason is that previous studies were either focused on laboratory-generated secondary organic aerosol (SOA) or based on field observations at locations more dominated by SOA.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1997

Chromosomal mutations and chromosome loss measured in a new human-hamster hybrid cell line, ALC: studies with colcemid, ultraviolet irradiation, and 137Cs gamma-rays

Small mutations, megabase deletions, and aneuploidy are involved in carcinogenesis and genetic defects, so it is important to be able to quantify these mutations and understand mechanisms of their creation. We have previously quantified a spectrum of mutations, including megabase deletions, in human chromosome 11, the sole human chromosome in a hamster-human hybrid cell line AL. S1- mutants have lost expression of a human cell surface antigen, S1, which is encoded by the M1C1 gene at 11p13 so that mutants can be detected via a complement-mediated cytotoxicity assay in which S1+ cells are killed and S1- cells survive. But loss of genes located on the tip of the short arm of 11 (11p15.5) is lethal to the AL hybrid, so that mutants that have lost the entire chromosome 11 die and escape detection. To circumvent this, we fused AL with Chinese hamster ovary (CHO) cells to produce a new hybrid, ALC, in which the requirement for maintaining 11p15.5 is relieved, allowing us to detect mutations events involving loss of 11p15.5. We evaluated the usefulness of this hybrid by conducting mutagenesis studies with colcemid, 137Cs gamma-radiation and UV 254 nm light. Colcemid induced 1000 more S1- mutants per unit dose in ALC than in AL; the increase for UV 254 nm light was only two-fold; and the increase for 137Cs gamma-rays was 12-fold. The increase in S1- mutant fraction in ALC cells treated with colcemid and 137Cs gamma-rays were largely due to chromosome loss and 11p deletions often containing a breakpoint within the centromeric region.

NASA Discipline Radiation Health↗

DOE OSTI2025

Magnetic properties of (Mo 2/3 Dy 1/3 ) 2 AlC arc melted polycrystalline samples

Here, this study investigates the structural and magnetic properties of arc-melted (Mo 2/3 Dy 1/3 ) 2 AlC polycrystalline samples, a member of the i-MAX phase family. Temperature-dependent magnetization and specific heat measurements confirm the low-temperature antiferromagnetic transitions around 14 K and 17 K. Neutron diffraction data collected at 4 K reveal the emergence of magnetic Bragg peaks that are not allowed in the paramagnetic space group C2/c, further confirming the presence of antiferromagnetic ordering. The detection of a secondary phase, DyAl 2 , is complicated by overlapping Bragg peaks with the monoclinic phase of (Mo 2/3 Dy 1/3 ) 2 AlC in powder XRD patterns. However, magnetization and neutron diffraction data suggest the presence of DyAl 2 , evidenced by a ferromagnetic phase transition around 62 K.

36 MATERIALS SCIENCE↗

DOE OSTI2022

A theoretical investigation of the effect of Ga alloying on thermodynamic stability, electronic-structure, and oxidation resistance of Ti 2 AlC MAX phase

We present a systematic investigation of thermodynamic stability, phase-reaction, and chemical activity of Al containing disordered Ti 2 (Al-Ga)C MAX phases using machine-learning driven high-throughput framework to understand the oxidation resistance behavior with increasing temperature and exposure to static oxygen. The A-site (at Al) disordering of Ti 2 AlC with Ga shows significant change in the chemical activity of Al with increasing temperature and exposure to static oxygen, which is expected to enable surface segregation of Al, thereby, the formation of Al 2 O 3 and improved oxidation resistance. We performed in-depth convex hull analysis of ternary Ti-Al-C, Ti-Ga-C, and Ti-Al-Ga-C based MAX phase, and provide detailed contribution arising from electronic, chemical and vibrational entropies. The thermodynamic analysis shows change in the Gibbs formation enthalpy (ΔG form ) at higher temperatures, which implies an interplay of temperature-dependent enthalpy and entropic contributions in oxidation resistance Ga doped Ti 2 AlC MAX phases. A detailed electronic structure and chemical bonding analysis using crystal orbital Hamilton population method reveal the origin of change in phases stability and in oxidation resistance in disorder Ti2(Al 1-x Ga x )C MAX phases. Our electronic structure analysis correlate well with the change in oxidation resistance of Ga doped MAX phases. We believe our study provides a useful guideline to understand to role of alloying on electronic, thermodynamic, and oxidation related mechanisms of bulk MAX phases, which can work as a precursor to understand oxidation behavior of twodimensional MAX phases, i.e., MXenes (transition metal carbides, carbonitrides and nitrides).

36 MATERIALS SCIENCE↗

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 OSTI2024

Porous Ti 3 AlC 2 MAX phase enables efficient synthesis of Ti 3 C 2 T x MXene

Abstract MXenes, a large family of two‐dimensional carbides and/or nitrides, are among the most studied materials worldwide due to their great diversity of structures and compositions. Their unique properties find use in several applications. Typically, they are manufactured by selective wet‐chemical etching of layered MAX phase ceramics, which are produced nowadays primarily for MXene synthesis. However, the synthesis of MAX phases has not been changed since the time of their use in structural and high‐temperature applications, and it has not been optimized for MXene manufacturing. The main purpose of this study is to develop a porous Ti 3 AlC 2 MAX phase that can be easily ground into individual grains without time‐consuming, harsh, and tedious crushing and milling steps. Moreover, we also demonstrate the synthesis of highly porous Ti 3 AlC 2 from an inexpensive titanium sponge instead of a highly pure titanium powder and explain the mechanisms of reaction sintering and formation of porous MAX phase. MXene obtained from this MAX phase, Ti 3 C 2 Tx, shows larger flake size and higher electrical conductivity in thin films, compared to the materials produced from the costly fine titanium powder. The proposed approach may apply to the synthesis of other MAX phases as well.

Materials Science↗

DOE OSTI2020

Materials Data on Th(AlC)4 by Materials Project

Th(AlC)4 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Th4+ is bonded in a body-centered cubic geometry to eight equivalent C4- atoms. All Th–C bond lengths are 2.76 Å. Al3+ is bonded to four equivalent C4- atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. There are a spread of Al–C bond distances ranging from 1.98–2.12 Å. C4- is bonded in a 6-coordinate geometry to two equivalent Th4+ and four equivalent Al3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Tb(AlC)3 by Materials Project

Tb(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tb3+ is bonded to six equivalent C4- atoms to form TbC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent TbC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Tb–C bond lengths are 2.57 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent TbC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent TbC6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are one shorter (2.02 Å) and three longer (2.11 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.99 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded in a 6-coordinate geometry to three equivalent Tb3+ and three equivalent Al3+ atoms. In the second C4- site, C4- is bonded to five Al3+ atoms to form corner-sharing CAl5 trigonal bipyramids.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Lu(AlC)3 by Materials Project

Lu(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Lu3+ is bonded to six equivalent C4- atoms to form LuC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent LuC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Lu–C bond lengths are 2.50 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent LuC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent LuC6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are one shorter (2.02 Å) and three longer (2.09 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.97 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Lu3+ and three equivalent Al3+ atoms to form distorted CLu3Al3 octahedra that share corners with three equivalent CLu3Al3 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine equivalent CLu3Al3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with six equivalent CLu3Al3 octahedra and corners with six equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ho(AlC)3 by Materials Project

Ho(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ho3+ is bonded to six equivalent C4- atoms to form HoC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent HoC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Ho–C bond lengths are 2.54 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent HoC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent HoC6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are one shorter (2.02 Å) and three longer (2.10 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.98 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded in a 6-coordinate geometry to three equivalent Ho3+ and three equivalent Al3+ atoms. In the second C4- site, C4- is bonded to five Al3+ atoms to form corner-sharing CAl5 trigonal bipyramids.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Tm(AlC)3 by Materials Project

Tm(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tm3+ is bonded to six equivalent C4- atoms to form TmC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent TmC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Tm–C bond lengths are 2.52 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent TmC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent TmC6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are one shorter (2.02 Å) and three longer (2.10 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.97 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Tm3+ and three equivalent Al3+ atoms to form distorted CTm3Al3 octahedra that share corners with three equivalent CTm3Al3 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine equivalent CTm3Al3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with six equivalent CTm3Al3 octahedra and corners with six equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ti3Nb(AlC)2 by Materials Project

Ti3Nb(AlC)2 is H-Phase-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are three inequivalent Ti sites. In the first Ti site, Ti is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ti–Al bond lengths are 2.90 Å. All Ti–C bond lengths are 2.10 Å. In the second Ti site, Ti is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ti–Al bond lengths are 2.89 Å. All Ti–C bond lengths are 2.11 Å. In the third Ti site, Ti is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ti–Al bond lengths are 2.88 Å. All Ti–C bond lengths are 2.12 Å. Nb is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Nb–Al bond lengths are 2.88 Å. All Nb–C bond lengths are 2.20 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Ti and six equivalent Al atoms to form distorted AlTi6Al6 cuboctahedra that share corners with six equivalent AlTi6Al6 cuboctahedra, corners with six CTi3Nb3 octahedra, edges with six equivalent AlTi6Al6 cuboctahedra, edges with six CTi3Nb3 octahedra, and faces with six equivalent AlTi6Al6 cuboctahedra. The corner-sharing octahedra tilt angles range from 19–20°. All Al–Al bond lengths are 3.07 Å. In the second Al site, Al is bonded to three equivalent Ti, three equivalent Nb, and six equivalent Al atoms to form distorted AlTi3Nb3Al6 cuboctahedra that share corners with six equivalent AlTi3Nb3Al6 cuboctahedra, corners with six CTi3Nb3 octahedra, edges with six equivalent AlTi3Nb3Al6 cuboctahedra, edges with six CTi3Nb3 octahedra, and faces with six equivalent AlTi3Nb3Al6 cuboctahedra. The corner-sharing octahedra tilt angles range from 16–19°. All Al–Al bond lengths are 3.07 Å. There are two inequivalent C sites. In the first C site, C is bonded to three equivalent Ti and three equivalent Nb atoms to form CTi3Nb3 octahedra that share corners with six AlTi6Al6 cuboctahedra, edges with six AlTi6Al6 cuboctahedra, and edges with six equivalent CTi3Nb3 octahedra. In the second C site, C is bonded to six Ti atoms to form CTi6 octahedra that share corners with six AlTi6Al6 cuboctahedra, edges with six AlTi6Al6 cuboctahedra, and edges with six equivalent CTi6 octahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on TiNb3(AlC)2 by Materials Project

TiNb3(AlC)2 is H-Phase-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. Ti is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ti–Al bond lengths are 2.89 Å. All Ti–C bond lengths are 2.12 Å. There are three inequivalent Nb sites. In the first Nb site, Nb is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Nb–Al bond lengths are 2.88 Å. All Nb–C bond lengths are 2.21 Å. In the second Nb site, Nb is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Nb–Al bond lengths are 2.86 Å. All Nb–C bond lengths are 2.19 Å. In the third Nb site, Nb is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Nb–Al bond lengths are 2.88 Å. All Nb–C bond lengths are 2.19 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Nb atoms to form distorted AlNb6 cuboctahedra that share corners with six CTi3Nb3 octahedra, edges with six equivalent AlNb6 cuboctahedra, and edges with six CTi3Nb3 octahedra. The corner-sharing octahedral tilt angles are 16°. In the second Al site, Al is bonded in a 12-coordinate geometry to three equivalent Ti and three equivalent Nb atoms. There are two inequivalent C sites. In the first C site, C is bonded to three equivalent Ti and three equivalent Nb atoms to form CTi3Nb3 octahedra that share corners with three equivalent AlNb6 cuboctahedra, edges with three equivalent AlNb6 cuboctahedra, and edges with six equivalent CTi3Nb3 octahedra. In the second C site, C is bonded to six Nb atoms to form CNb6 octahedra that share corners with three equivalent AlNb6 cuboctahedra, edges with three equivalent AlNb6 cuboctahedra, and edges with six equivalent CNb6 octahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Er(AlC)3 by Materials Project

Er(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Er3+ is bonded to six equivalent C4- atoms to form ErC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent ErC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Er–C bond lengths are 2.53 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent ErC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent ErC6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are one shorter (2.02 Å) and three longer (2.10 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.97 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Er3+ and three equivalent Al3+ atoms to form distorted CEr3Al3 octahedra that share corners with three equivalent CEr3Al3 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine equivalent CEr3Al3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with six equivalent CEr3Al3 octahedra and corners with six equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Dy(AlC)3 by Materials Project

Dy(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Dy3+ is bonded to six equivalent C4- atoms to form DyC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent DyC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Dy–C bond lengths are 2.56 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent DyC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent DyC6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are one shorter (2.02 Å) and three longer (2.10 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.98 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded in a 6-coordinate geometry to three equivalent Dy3+ and three equivalent Al3+ atoms. In the second C4- site, C4- is bonded to five Al3+ atoms to form corner-sharing CAl5 trigonal bipyramids.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Zr(AlC)4 by Materials Project

Zr(AlC)4 crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are two inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six C4- atoms to form ZrC6 octahedra that share corners with three equivalent ZrC6 octahedra, corners with three equivalent AlC4 tetrahedra, edges with nine ZrC6 octahedra, and edges with three equivalent AlC4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.37 Å) and three longer (2.39 Å) Zr–C bond lengths. In the second Zr4+ site, Zr4+ is bonded to six C4- atoms to form ZrC6 octahedra that share corners with three equivalent ZrC6 octahedra, corners with three equivalent AlC4 tetrahedra, edges with nine ZrC6 octahedra, and edges with three equivalent AlC4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.37 Å) and three longer (2.39 Å) Zr–C bond lengths. There are eight inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. There are one shorter (1.94 Å) and three longer (2.18 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. There are one shorter (1.94 Å) and three longer (2.18 Å) Al–C bond lengths. In the third Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent ZrC6 octahedra, corners with six equivalent AlC4 tetrahedra, corners with four AlC4 trigonal pyramids, and edges with three equivalent ZrC6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are one shorter (1.95 Å) and three longer (2.13 Å) Al–C bond lengths. In the fourth Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent ZrC6 octahedra, corners with six equivalent AlC4 tetrahedra, corners with four AlC4 trigonal pyramids, and edges with three equivalent ZrC6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are one shorter (1.95 Å) and three longer (2.13 Å) Al–C bond lengths. In the fifth Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of distorted edge and corner-sharing AlC4 trigonal pyramids. There are three shorter (1.97 Å) and one longer (2.17 Å) Al–C bond lengths. In the sixth Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. There are three shorter (1.97 Å) and one longer (2.16 Å) Al–C bond lengths. In the seventh Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. There are three shorter (1.96 Å) and one longer (2.21 Å) Al–C bond lengths. In the eighth Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. There are three shorter (1.96 Å) and one longer (2.20 Å) Al–C bond lengths. There are eight inequivalent C4- sites. In the first C4- site, C4- is bonded to six Al3+ atoms to form CAl6 octahedra that share corners with six CAl5 trigonal bipyramids and edges with six equivalent CAl6 octahedra. In the second C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CZr3Al3 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 65°. In the third C4- site, C4- is bonded to six Zr4+ atoms to form a mixture of edge and corner-sharing CZr6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the fourth C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CAl6 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 63°. In the fifth C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CZr3Al3 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 65°. In the sixth C4- site, C4- is bonded to three equivalent Zr4+ and three equivalent Al3+ atoms to form CZr3Al3 octahedra that share corners with three equivalent CZr6 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine CZr6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the seventh C4- site, C4- is bonded to three equivalent Zr4+ and three equivalent Al3+ atoms to form CZr3Al3 octahedra that share corners with three equivalent CZr6 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine CZr3Al3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the eighth C4- site, C4- is bonded to five Al3+ atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent CAl6 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°.

36 MATERIALS SCIENCE↗