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DOE OSTI2020

Materials Data on Cd2Bi2(TeSe)3 by Materials Project

Cd2Bi2(TeSe)3 is Caswellsilverite-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to three equivalent Te2- and three equivalent Se2- atoms to form CdTe3Se3 octahedra that share corners with three equivalent BiSe6 octahedra, edges with three equivalent BiSe6 octahedra, and edges with six equivalent CdTe3Se3 octahedra. The corner-sharing octahedral tilt angles are 4°. All Cd–Te bond lengths are 2.96 Å. All Cd–Se bond lengths are 2.96 Å. In the second Cd2+ site, Cd2+ is bonded to three equivalent Te2- and three equivalent Se2- atoms to form CdTe3Se3 octahedra that share corners with three equivalent BiTe3Se3 octahedra, corners with three equivalent SeBi3Te3 octahedra, edges with three equivalent BiTe3Se3 octahedra, edges with three equivalent SeBi3Te3 octahedra, and edges with six equivalent CdTe3Se3 octahedra. The corner-sharing octahedra tilt angles range from 2–15°. All Cd–Te bond lengths are 2.91 Å. All Cd–Se bond lengths are 3.01 Å. There are two inequivalent Bi4+ sites. In the first Bi4+ site, Bi4+ is bonded to three equivalent Te2- and three equivalent Se2- atoms to form BiTe3Se3 octahedra that share corners with three equivalent CdTe3Se3 octahedra, edges with three equivalent CdTe3Se3 octahedra, and edges with six equivalent BiTe3Se3 octahedra. The corner-sharing octahedral tilt angles are 2°. All Bi–Te bond lengths are 3.09 Å. All Bi–Se bond lengths are 3.08 Å. In the second Bi4+ site, Bi4+ is bonded to six Se2- atoms to form BiSe6 octahedra that share corners with three equivalent CdTe3Se3 octahedra, corners with three equivalent TeCd3Se3 octahedra, edges with three equivalent CdTe3Se3 octahedra, edges with three equivalent TeCd3Se3 octahedra, and edges with six equivalent BiSe6 octahedra. The corner-sharing octahedra tilt angles range from 4–14°. There are three shorter (2.91 Å) and three longer (3.12 Å) Bi–Se bond lengths. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Cd2+ and three equivalent Te2- atoms. All Te–Te bond lengths are 3.46 Å. In the second Te2- site, Te2- is bonded to three equivalent Cd2+ and three equivalent Se2- atoms to form distorted TeCd3Se3 octahedra that share corners with three equivalent BiSe6 octahedra, corners with three equivalent SeCd3Bi3 octahedra, edges with three equivalent BiSe6 octahedra, edges with three equivalent SeCd3Bi3 octahedra, and edges with six equivalent TeCd3Se3 octahedra. The corner-sharing octahedra tilt angles range from 3–14°. All Te–Se bond lengths are 3.60 Å. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Bi4+ and three equivalent Te2- atoms. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Bi4+ and three equivalent Te2- atoms to form distorted SeBi3Te3 octahedra that share corners with three equivalent CdTe3Se3 octahedra, corners with three equivalent SeCd3Bi3 octahedra, edges with three equivalent CdTe3Se3 octahedra, and edges with nine SeBi3Te3 octahedra. The corner-sharing octahedra tilt angles range from 5–15°. In the second Se2- site, Se2- is bonded to three equivalent Cd2+ and three equivalent Bi4+ atoms to form a mixture of corner and edge-sharing SeCd3Bi3 octahedra. The corner-sharing octahedral tilt angles are 5°. In the third Se2- site, Se2- is bonded to three equivalent Cd2+ and three equivalent Bi4+ atoms to form SeCd3Bi3 octahedra that share corners with three equivalent TeCd3Se3 octahedra, edges with three equivalent TeCd3Se3 octahedra, and edges with six equivalent SeCd3Bi3 octahedra. The corner-sharing octahedral tilt angles are 3°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd2TeSe by Materials Project

Cd2TeSe is Lavarevi\'{c}ite-like structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to three equivalent Te2- and one Se2- atom to form corner-sharing CdTe3Se tetrahedra. All Cd–Te bond lengths are 2.82 Å. The Cd–Se bond length is 2.68 Å. In the second Cd2+ site, Cd2+ is bonded to one Te2- and three equivalent Se2- atoms to form corner-sharing CdTeSe3 tetrahedra. The Cd–Te bond length is 2.88 Å. All Cd–Se bond lengths are 2.74 Å. Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with six equivalent TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra. Se2- is bonded to four Cd2+ atoms to form SeCd4 tetrahedra that share corners with six equivalent TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdPb3 by Materials Project

CdPb3 is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Cd is bonded to twelve Pb atoms to form CdPb12 cuboctahedra that share corners with four equivalent CdPb12 cuboctahedra, edges with eight equivalent CdPb12 cuboctahedra, edges with sixteen equivalent PbCd4Pb8 cuboctahedra, faces with four equivalent CdPb12 cuboctahedra, and faces with eight equivalent PbCd4Pb8 cuboctahedra. There are four shorter (3.40 Å) and eight longer (3.55 Å) Cd–Pb bond lengths. There are two inequivalent Pb sites. In the first Pb site, Pb is bonded to four equivalent Cd and eight Pb atoms to form distorted PbCd4Pb8 cuboctahedra that share corners with twelve equivalent PbCd4Pb8 cuboctahedra, edges with eight equivalent CdPb12 cuboctahedra, edges with eight equivalent PbCd4Pb8 cuboctahedra, faces with four equivalent CdPb12 cuboctahedra, and faces with ten equivalent PbCd4Pb8 cuboctahedra. There are four shorter (3.40 Å) and four longer (3.55 Å) Pb–Pb bond lengths. In the second Pb site, Pb is bonded in a square co-planar geometry to four equivalent Cd and eight equivalent Pb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnCd4S5 by Materials Project

MnCd4S5 is Enargite-like structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. Mn2+ is bonded to four S2- atoms to form MnS4 tetrahedra that share corners with six equivalent MnS4 tetrahedra and corners with six CdS4 tetrahedra. There are one shorter (2.42 Å) and three longer (2.50 Å) Mn–S bond lengths. There are four inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four S2- atoms to form CdS4 tetrahedra that share corners with three equivalent MnS4 tetrahedra and corners with nine CdS4 tetrahedra. All Cd–S bond lengths are 2.57 Å. In the second Cd2+ site, Cd2+ is bonded to four S2- atoms to form corner-sharing CdS4 tetrahedra. There are one shorter (2.55 Å) and three longer (2.56 Å) Cd–S bond lengths. In the third Cd2+ site, Cd2+ is bonded to four S2- atoms to form corner-sharing CdS4 tetrahedra. There are three shorter (2.55 Å) and one longer (2.56 Å) Cd–S bond lengths. In the fourth Cd2+ site, Cd2+ is bonded to four S2- atoms to form CdS4 tetrahedra that share corners with three equivalent MnS4 tetrahedra and corners with nine CdS4 tetrahedra. There are three shorter (2.57 Å) and one longer (2.59 Å) Cd–S bond lengths. There are five inequivalent S2- sites. In the first S2- site, S2- is bonded to four Cd2+ atoms to form corner-sharing SCd4 tetrahedra. In the second S2- site, S2- is bonded to four Cd2+ atoms to form corner-sharing SCd4 tetrahedra. In the third S2- site, S2- is bonded to four Cd2+ atoms to form corner-sharing SCd4 tetrahedra. In the fourth S2- site, S2- is bonded to three equivalent Mn2+ and one Cd2+ atom to form corner-sharing SMn3Cd tetrahedra. In the fifth S2- site, S2- is bonded to one Mn2+ and three equivalent Cd2+ atoms to form corner-sharing SMnCd3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbV3Cd4O12 by Materials Project

RbV3Cd4O12 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Rb1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Rb–O bond distances ranging from 2.80–3.44 Å. There are three inequivalent V5+ sites. In the first V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four CdO6 octahedra and corners with two equivalent CdO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of V–O bond distances ranging from 1.74–1.78 Å. In the second V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four CdO6 octahedra and corners with two equivalent CdO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 40–66°. There are a spread of V–O bond distances ranging from 1.72–1.78 Å. In the third V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four CdO6 octahedra and corners with two equivalent CdO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 39–65°. There are a spread of V–O bond distances ranging from 1.71–1.81 Å. There are four inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six O2- atoms to form distorted CdO6 pentagonal pyramids that share corners with six VO4 tetrahedra and edges with two CdO6 octahedra. There are a spread of Cd–O bond distances ranging from 2.36–2.41 Å. In the second Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with six VO4 tetrahedra, an edgeedge with one CdO6 octahedra, and an edgeedge with one CdO6 pentagonal pyramid. There are a spread of Cd–O bond distances ranging from 2.27–2.33 Å. In the third Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with six VO4 tetrahedra, an edgeedge with one CdO6 octahedra, and an edgeedge with one CdO6 pentagonal pyramid. There are a spread of Cd–O bond distances ranging from 2.25–2.34 Å. In the fourth Cd2+ site, Cd2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cd–O bond distances ranging from 2.31–2.92 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Rb1+, one V5+, and one Cd2+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Rb1+, one V5+, and one Cd2+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one V5+ and three Cd2+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one V5+ and two Cd2+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one Rb1+, one V5+, and two Cd2+ atoms. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Rb1+, one V5+, and two Cd2+ atoms. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Rb1+, one V5+, and two Cd2+ atoms. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one Rb1+, one V5+, and two Cd2+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one V5+ and two Cd2+ atoms. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one V5+ and three Cd2+ atoms. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to one Rb1+, one V5+, and two Cd2+ atoms. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to one Rb1+, one V5+, and two Cd2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd4As2Br3 by Materials Project

Cd4As2Br3 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. there are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded in a rectangular see-saw-like geometry to two As+2.50- and two equivalent Br1- atoms. There are one shorter (2.60 Å) and one longer (2.62 Å) Cd–As bond lengths. There are one shorter (2.85 Å) and one longer (3.04 Å) Cd–Br bond lengths. In the second Cd2+ site, Cd2+ is bonded in a rectangular see-saw-like geometry to one As+2.50- and three equivalent Br1- atoms. The Cd–As bond length is 2.60 Å. All Cd–Br bond lengths are 2.81 Å. There are two inequivalent As+2.50- sites. In the first As+2.50- site, As+2.50- is bonded to three equivalent Cd2+ and one As+2.50- atom to form corner-sharing AsCd3As tetrahedra. The As–As bond length is 2.44 Å. In the second As+2.50- site, As+2.50- is bonded to four Cd2+ atoms to form corner-sharing AsCd4 trigonal pyramids. Br1- is bonded in a trigonal non-coplanar geometry to three Cd2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdP3NO9 by Materials Project

(Cd(PO3)3)2N2 crystallizes in the hexagonal P-6c2 space group. The structure is three-dimensional and consists of two ammonia molecules and one Cd(PO3)3 framework. In the Cd(PO3)3 framework, Cd2+ is bonded to six equivalent O2- atoms to form CdO6 octahedra that share corners with six equivalent PO4 tetrahedra. All Cd–O bond lengths are 2.30 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CdO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cd2+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Strong Rashba-Dresselhaus Effect in Nonchiral 2D Ruddlesden-Popper Perovskites

Chirality transfer from organic chiral molecules to lead halides is theorized as the origin of the strong Rashba-Dresselhaus effect causing large circular dichroism (CD) and circularly polarized luminescence (CPL) in metal halide perovskites (MHPs). In this report a concrete empirical evidence is provided that such strong CD and CPL can occur even in nonchiral 2D Ruddlesden-Popper perovskites (RPPs) (BA) 2 (MA) n-1 Pb n I 3n+1 (where MA = CH 3 NH 3 and BA = CH 3 (CH 2 ) 3 NH 3 ). The CD and CPL responses occurring at the excitonic transition of the MHPs are strongest (≈100 mdeg and 4.8%, respectively) when a single lead halide octahedral [PbI 6 ] 4- layer is repeatedly stacked between two nonchiral molecules BA + (n = 1). However, they are rapidly quenched as n increases. It is hypothesized that strong Rashba-Dresselhaus splitting in the 2D RPPs originates the strong CD and CPL signatures. Density functional theory calculations reveal that the large interlayer distortions in the inorganic layers at the organic/inorganic interface give rise to the strong Rashba-Dresselhaus splitting. A Rashba-Dresselhaus field of ≈600 and ≈50 mT for n = 1 and 2, respectively, is estimated by magnetic circular dichroism spectroscopy. The studies may have significant impact on designing 2D RPPs with large Rashba-Dresselhaus effects at room temperature for spintronic applications.

circular dichroism↗
DOE OSTI2022

Strong Induced Circular Dichroism in a Hybrid Lead‐Halide Semiconductor Using Chiral Amino Acids for Crystallite Surface Functionalization

Abstract Chirality is a desired property in functional semiconductors for optoelectronic, catalytic, and spintronic applications. Here, introducing enantiomerically‐pure 3‐aminobutyric acid (3‐ABA) into thin films of the 1D semiconductor dimethylammonium lead iodide (DMAPbI 3 ) is found to result in strong circular dichroism (CD) in the optical absorption. X‐ray diffraction and grazing incidence small angle X‐ray scattering (GISAXS) are applied to gain molecular‐scale insights into the chirality transfer mechanism, which is attributed to a chiral surface modification of DMAPbI 3 crystallites. This study demonstrates that the CD signal strength can be controlled by the amino‐acid content relative to the crystallite surface area. The CD intensity is tuned by the composition of the precursor solution and the spin‐coating time, thereby achieving anisotropy factors ( g abs ) as high as 1.75 × 10 –2 . Grazing incidence wide angle scattering reveals strong preferential ordering that can be suppressed via tailored synthesis conditions. Different contributions to the chiroptical properties are resolved by a detailed analysis of the CD signal utilizing an approach based on the Mueller matrix model. This report of a novel class of chiral hybrid semiconductors with precise control over their optical activity presents a promising approach for the design of circularly polarized light detectors and emitters.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Hierarchically Templated Synthesis of 3D‐Printed Crosslinked Cyclodextrins for Lycopene Harvesting

Abstract Plants produce a wide range of bioactive phytochemicals, such as antioxidants and vitamins, which play crucial roles in aging prevention, inflammation reduction, and reducing the risk of cancer. Selectively harvesting these phytochemicals, such as lycopene, from tomatoes through the adsorption method is cost‐effective and energy efficient. In this work, a templated synthesis of 3D‐printed crosslinked cyclodextrin polymers featuring nanotubular structures for highly selective lycopene harvesting is reported. Polypseudorotaxanes formed by triethoxysilane‐based telechelic polyethylene glycols and α‐cyclodextrins (α‐CDs) are designed as the template to (1) synthetically access urethane‐based nanotubular structures at the molecular level, and (2) construct 3D‐printed architectures with designed macroscale voids. The polypseudorotaxane hydrogels showed good rheological properties for direct ink writing, and the 3D‐printed hydrogels were converted to the desired α‐CD polymer network through a three‐step postprinting transformation. The obtained urethane‐crosslinked α‐CD monoliths possess nanotubular structures and 3D‐printed voids. They selectively adsorb lycopene from raw tomato juice, protecting lycopene from photo‐ or thermo‐degradations. This work highlights the hierarchically templated synthesis approach in developing functional 3D‐printing materials by connecting the bottom‐up molecular assembly and synthesis with the top‐down 3D architecture control and fabrication.

Chemistry↗
DOE OSTI2022

Morphological and crystallographic controls in the replacement of calcite and aragonite by cerussite and otavite

Mineral replacement reactions are essential solid-fluid interactions in natural and industrial processes including metasomatism, diagenesis, and metamorphism, and sequestration of metal toxins from polluted water. In this paper, we explore the morphological evolution of aragonite and calcite (polymorphs of CaCO 3 ) during their replacement by cerussite (PbCO 3 , an isomorph of aragonite) and otavite (CdCO 3 , an isomorph of calcite) in acidic aqueous solutions (with initial pH 3 to 4). Observations using scanning electron and synchrotron-based transmission X-ray microscopies reveal the formation of pseudomorphic shells (~5 to 10 µm thick) of cerussite and otavite when Pb 2+ is reacted with either calcite or aragonite and when Cd 2+ is reacted with aragonite. The formation of pore space at the substrate-precipitate interface and within the precipitate is found to be key in promoting chemical exchange between the dissolving phase and the solution. In contrast, minimal reactivity is observed when Cd 2+ is reacted with calcite. These results demonstrate that the lack of substrate-precipitate epitaxy (either because of inconsistent symmetries or due to large lattice constant mismatch) is a critical factor that enables replacement of primary CaCO 3 minerals by Pb- or Cd-bearing secondary minerals while the presence of epitaxial relationships inhibit those reactions. When calcite and aragonite coexist, the replacement of aragonite by cerussite and otavite occurs preferentially over calcite. We postulate that the relative reactivity of calcite and aragonite to Pb 2+ and Cd 2+ can be determined by interplay between morphological and crystallographic properties of CaCO 3 materials as well as solution chemistry. Our results demonstrate that coupled dissolution-precipitation processes of carbonate minerals play an important role in controlling mobility and bioavailability of lead and cadmium in environments where acidic metal-contaminated water interacts with carbonate-rich rocks and soils.

58 GEOSCIENCES↗
DOE OSTI2023

Evolution of dislocation loops and voids in post-irradiation annealed ThO 2 : A combined in-situ TEM and cluster dynamics investigation

The effect of isochronal annealing on the evolution of dislocation loop and void population in proton irradiated ThO 2 has been investigated. Post-irradiation annealing in other actinide oxides like UO 2 shows significant loop coarsening. ThO 2 samples were irradiated with 2 MeV protons up to a dose of 0.1 dpa at 600°C. Post-irradiation isochronal annealing was performed at 600, 800, 1000 and 1100°C for 1 h at each temperature using in-situ TEM. Only faulted 1/3<111> type dislocation loops were observed, and their sizes and distribution were characterized. Further, the population of self-interstitial atom (SIA) dislocation loops did not show any significant growth and coarsening. Additionally, nanometric voids were observed at annealing temperatures of 1000 and 1100°C. Using cluster dynamics (CD), we have studied the nucleation and growth of point defects and defect clusters, i.e., SIA prismatic dislocation loops and nanometric and sub-nanometric voids in proton irradiated ThO 2 . The CD model was further utilized to predict the growth and coarsening of loops and voids during isochronal annealing at the experimental and higher temperatures. The model did not predict significant SIA loop growth which closely corresponds to the TEM observations. CD predicted SIA loop coarsening is insignificant even at high annealing temperature of 1500°C because the model only considers the growth of defect clusters by absorption of like point defects, i.e., SIA loops absorb interstitials and voids absorb vacancies, and cannot account for their migration and coalescence due to elastic interaction. The CD model also predicts the evolution of nanometric voids having mean size within the error bounds of TEM observations.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Computational design of passivants for CdTe grain boundaries

CdTe is the second most-widely deployed photovoltaic (PV) material due to its high efficiency and low manufacturing costs. Currently, polycrystalline CdTe (poly-CdTe) has a record efficiency of similar to 22%, which is still well below the theoretical limit (similar to 30%). Polycrystalline CdTe films that have incorporated Cl or Se show higher efficiency, possibly due to the segregation of these ions to the grain boundaries (GBs), where they may passivate the dangling bonds. However, the efficiency enhancement mechanisms of passivants in CdTe GBs, and the feasibility of employing alternative passivants, have not been well explored. Here, we present a systematic computational study of CdTe GBs with potential passivants, namely S, P, As, Se, and Sb on Te sites, and Na, Mg, Al, Sc, Cu, and Zn on Cd sites. Density functional theory (DFT) calculations were performed on GB dislocation core structures derived from scanning transmission electron microscopy (STEM) images of a model GB (bicrystal). We computed the segregation thermodynamics, electronic density of states, and charge variations near doped CdTe GBs. We find that segregation of impurities to GBs is thermodynamically favorable. For a Te-terminated core, Se, S, and P on Te sites effectively reduce midgap states. For both Cd-and Te-terminated dislocation cores, Sc and Al reduce midgap states when substituted for Cd atoms. Overall, the greatest improvement was achieved with co-doping, i.e. simultaneously substituting Te with Se and substituting Cd with Cu or Al. The elimination of midgap states is predicted to increase the photovoltaic efficiency of CdTe by reducing the recombination at grain boundaries.

14 SOLAR ENERGY↗
DOE OSTI2022

Solvent-Driven Transformation of Zn/Cd 2+ -Deoxycholate Assemblies

Deoxycholic acid (DOC) is a unique, biologically derived surfactant with facial amphiphilicity that has been exploited, albeit minimally, in supramolecular assembly of materials. Here, we present the synthesis and structural characterization of three hybrid metal (Zn 2+ and Cd 2+ )-DOC compounds. Analysis by single-crystal Xray diffraction reveals the many interactions that are possible between these facial surfactants and the influence of solvent molecules that drive the assembly of materials. These structures are the first metal- DOC complexes besides those obtained from alkali and alkaline earth metals. We isolated polymeric chains of both Cd and Zn (Zn poly -DOC and Cd poly -DOC) from water. Major interactions between DOC molecules in these phases are hydrophobic in nature. Cd poly -DOC exhibits unique P1 symmetry, with complete interdigitation of the amphiphiles between neighboring polymeric chains. Zn 4 -DOC, obtained from methanol dissolution of Zn poly -DOC, features the OZn 4 tetrahedron, widely known in basic zinc acetate and MOF-5 (metal organic framework). We document a solvent-driven, roomtemperature transition between Zn poly -DOC and Zn 4 -DOC (in both directions) by scanning and transmission electron microscopies in addition to small-angle X-ray scattering, powder X-ray diffraction, and infrared spectroscopy. These studies show the methanoldriven transition of Zn poly -DOC to Zn 4 -DOC occurs via an intermediate with no long-range order of the Zn 4 clusters, indicating the strongest interactions driving assembly are intramolecular. On the contrary, water-driven solid-to-solid transformation from Zn 4 -DOC to Zn poly -DOC exhibits crystal-to-crystal transformation. Zn poly -DOC is robust, easy to synthesize, and comprised of biologically benign components, so we demonstrate dye absorption as a proxy for water treatment applications. It favors absorption of positively charged dyes. These studies advance molecular level knowledge of the supramolecular assembly of facial surfactants that can be exploited in the design of organic-inorganic hybrid materials. This research also highlights the potential of solvent for tuning supramolecular assembly processes, leading to new hybrid materials featuring facial surfactants.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Cholesky Decomposition-Based Implementation of Relativistic Two-Component Coupled-Cluster Methods for Medium-Sized Molecules

A Cholesky decomposition (CD)-based implementation of relativistic two-component coupled-cluster (CC) and equation-of-motion CC (EOM-CC) methods using an exact two-component Hamiltonian augmented with atomic-mean-field integrals (the X2CAMF scheme) is reported. Furthermore, the present CD-based implementation of X2CAMF-CC and EOM-CC methods employs atomic-orbital-based algorithms to avoid the construction of two-electron integrals and intermediates involving three and four virtual indices. The CD-based implementation extends the applicability of X2CAMF-CC and EOMCC methods to medium-sized molecules with the correlation of around 1000 spinors. Benchmark calculations for uranium-containing small molecules have been performed to assess the dependence of CC results with respect to the Cholesky threshold. A Cholesky threshold of 10 –4 is shown to maintain chemical accuracy. Example calculations to illustrate the capability of the CD-based relativistic CC methods are reported for the bond dissociation energy of the uranium hexafluoride molecule, UF 6 , with up to quadruple-zeta basis sets and the lowest excitation energy in solvated uranyl ion [UO 2 2+ (H 2 O) 12 ].

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Ligand Coverage and Exciton Delocalization Control Chiral Imprinting in Perovskite Nanoplatelets

Chiral perovskites have generated significant recent interest, yet little is known about how their chiro-optical properties arise. In this study, chiral methylammonium lead halide perovskite nanoplatelets (NPLs) with varied halide and ligand compositions are prepared using direct synthetic methods. Circular dichroism (CD) and 1 H NMR studies find a non-linear relationship between the chiroptical properties and the ratio of chiral phenylethylammonium (PEA) to achiral octylamine (OA) ligands on the NPL surface. We use density functional theory (DFT) computations and a chiral imprinted particle-in-a-box model to rationalize the experimentally observed CD spectra and find that the saturation point of the induced chirality depends on the size of the perovskite exciton relative to the size of the ligands. Temperature-dependent CD and 1 H NMR studies, combined with DFT analysis, show that both the CD intensity and sign depend strongly on the structure and orientation of the ligands. Furthermore, this work reveals the complex nature of chiral imprinting in perovskite nanostructures and establishes a simple physical model for ligand-induced chiral imprinting to guide the further development of chiral materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Highly Elliptic Circular Dichroism of Copper Aspartate One-Dimensional Nanostructures across the Ultraviolet to Terahertz Ranges

Since the discovery of chirality, circular dichroism (CD) of mirror-asymmetric molecules has been studied across the ultraviolet, visible, and near-infrared ranges. Recently, chiroptical activity studies have expanded to the terahertz (THz) range, where resonance peaks originate from collective vibrations of tens and hundreds of atoms. Here, in this study, we synthesized Cu 2+ coordination complexes with L- and D-aspartic acid as nanowires and nanorods and characterized their chiroptical activity across multiple frequency ranges. Both chiral nanostructures exhibit strong electronic CD (ECD), primarily from Cu 2+ d-d transitions, while vibrational CD (VCD) spectra show sharp C=O, C–H, and O–H vibronic peaks, indicating higher atomic defect densities in nanorods than nanowires. Although THz CD (TCD) spectra are broad, they exhibit ∼1000× greater ellipticity than ECD and VCD, perhaps warranting previous references to circular dichroism of nanostructures as giant. Comparative TCD analysis highlights strong chiral phonon sensitivity, underscoring its potential for probing defect densities and structural changes for various chiral nanostructures and (bio)crystals.

THz spectroscopy↗
DOE OSTI2025

Tuning Chiral Anomaly Signature in a Dirac Semimetal via Fast-Ion Implantation

Cd 3 As 2 is a Dirac semimetal that hosts a chiral anomaly, functioning as a platform to realize energy applications. We use fast-ion implantation to enhance the negative longitudinal magnetoresistance (NLMR)─signature of a chiral anomaly─in Nb-doped Cd 3 As 2 thin films. High-energy ion implantation is used to investigate semiconductors and nuclear materials but is rarely employed to study topological materials. We use electrical transport and transmission electron microscopy to characterize the NLMR and crystallinity of Nb-doped Cd 3 As 2 . We find surface-doped thin films display a maximum NLMR around B = 7 T and bulk-doped thin films display a maximum over B = 9 T─all while maintaining crystallinity. This is more than a 100% relative enhancement of the maximum NLMR compared to pristine Cd 3 As 2 . As a result, our work demonstrates the potential of high-energy ion implantation as a practical route to explore chiralitronic properties in topological semimetals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗