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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on YEr(SnPd2)2 by Materials Project

ErY(Pd2Sn)2 is Tungsten-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Er is bonded in a body-centered cubic geometry to eight Pd and six equivalent Sn atoms. There are two shorter (2.92 Å) and six longer (2.94 Å) Er–Pd bond lengths. All Er–Sn bond lengths are 3.39 Å. Y is bonded in a body-centered cubic geometry to eight Pd and six equivalent Sn atoms. There are two shorter (2.94 Å) and six longer (2.95 Å) Y–Pd bond lengths. All Y–Sn bond lengths are 3.39 Å. There are six inequivalent Pd sites. In the first Pd site, Pd is bonded in a body-centered cubic geometry to three equivalent Er, one Y, and four equivalent Sn atoms. There are one shorter (2.92 Å) and three longer (2.95 Å) Pd–Sn bond lengths. In the second Pd site, Pd is bonded in a body-centered cubic geometry to one Er, three equivalent Y, and four equivalent Sn atoms. All Pd–Sn bond lengths are 2.94 Å. In the third Pd site, Pd is bonded in a body-centered cubic geometry to one Er, three equivalent Y, and four equivalent Sn atoms. All Pd–Sn bond lengths are 2.94 Å. In the fourth Pd site, Pd is bonded in a body-centered cubic geometry to three equivalent Er, one Y, and four equivalent Sn atoms. There are one shorter (2.92 Å) and three longer (2.95 Å) Pd–Sn bond lengths. In the fifth Pd site, Pd is bonded in a body-centered cubic geometry to three equivalent Er, one Y, and four equivalent Sn atoms. All Pd–Er bond lengths are 2.94 Å. The Pd–Y bond length is 2.94 Å. There are one shorter (2.92 Å) and three longer (2.95 Å) Pd–Sn bond lengths. In the sixth Pd site, Pd is bonded in a body-centered cubic geometry to one Er, three equivalent Y, and four equivalent Sn atoms. The Pd–Er bond length is 2.92 Å. All Pd–Y bond lengths are 2.95 Å. All Pd–Sn bond lengths are 2.94 Å. Sn is bonded in a distorted body-centered cubic geometry to three equivalent Er, three equivalent Y, and eight Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YEr by Materials Project

ErY is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Er is bonded to six equivalent Er and six equivalent Y atoms to form ErY6Er6 cuboctahedra that share corners with eighteen equivalent ErY6Er6 cuboctahedra, edges with six equivalent ErY6Er6 cuboctahedra, edges with twelve equivalent YY6Er6 cuboctahedra, faces with eight equivalent ErY6Er6 cuboctahedra, and faces with twelve equivalent YY6Er6 cuboctahedra. All Er–Er bond lengths are 3.59 Å. All Er–Y bond lengths are 3.54 Å. Y is bonded to six equivalent Er and six equivalent Y atoms to form YY6Er6 cuboctahedra that share corners with eighteen equivalent YY6Er6 cuboctahedra, edges with six equivalent YY6Er6 cuboctahedra, edges with twelve equivalent ErY6Er6 cuboctahedra, faces with eight equivalent YY6Er6 cuboctahedra, and faces with twelve equivalent ErY6Er6 cuboctahedra. All Y–Y bond lengths are 3.59 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Singular Hall Response from a Correlated Ferromagnetic Flat Nodal‐Line Semimetal

Abstract Topological quantum phases are largely understood in weakly correlated systems, which have identified various quantum phenomena, such as the spin Hall effect, protected transport of helical fermions, and topological superconductivity. Robust ferromagnetic order in correlated topological materials particularly attracts attention, as it can provide a versatile platform for novel quantum devices. Here, a singular Hall response arising from a unique band structure of flat topological nodal lines in combination with electron correlation in a van der Waals ferromagnetic semimetal, Fe 3 GaTe 2 , with a high Curie temperature ofT c = 347 K is reported. High anomalous Hall conductivity violating the conventional scaling, resistivity upturn at low temperature, and a large Sommerfeld coefficient are observed in Fe 3 GaTe 2 , which implies heavy fermion features in this ferromagnetic topological material. The scanning tunneling microscopy, circular dichroism in angle‐resolved photoemission spectroscopy, and theoretical calculations support the original electronic features of the material. Thus, low‐dimensional Fe 3 GaTe 2 with electronic correlation, topology, and room‐temperature ferromagnetic order appears to be a promising candidate for robust quantum devices.

Chemistry↗
DOE OSTI2025

Flash Communication: Boron K-edge XAS and TDDFT Studies of Covalent Metal–Ligand Bonding in Ni(C 2 B 9 H 11 ) 2

Ligand K-edge X-ray absorption spectroscopy (XAS), a technique that can measure variations in covalent metal–ligand bonding, has rarely been used to assess covalency in complexes containing metal–boron bonds. Here we describe ligand K-edge XAS and TDDFT studies of the Ni dicarbollide complex Ni(C 2 B 9 H 11 ) 2 (1) and the Ni-free salt (HNMe 3 )(C 2 B 9 H 12 ) (L1). The XAS spectrum for 1 reveals a pre-edge feature indicative of covalent Ni–B bonding, which is corroborated by time-dependent density functional theory (TDDFT) calculations and comparative analysis to L1 and inner-shell electron energy loss spectroscopy (ISEELS) collected on the same Ni complex.

Boron↗
DOE OSTI2025

Direct measurement of covalent three-center, two-electron M–H–B bonding in Zr and Hf borohydrides using B K-edge XAS

Metal borohydride complexes have long been the subject of intense fundamental interest because of their unconventional metal–ligand bonding that occurs via three-center, two-electron M–H–B bonds. This type of bonding implies significant delocalization of electron density over all three atoms, but the degree of orbital mixing between the metal and boron has been difficult to assess by direct experimental means. Herein, we demonstrate how ligand K-edge X-ray absorption spectroscopy (XAS) conducted at the B K-edge yields evidence of significant covalent M–H–B bonding with Zr and Hf. To accommodate the B K-edge XAS studies, which were conducted under ultra-high vacuum (<10 −8 torr), we prepared a series of new [Zr(RBH 3 ) 4 ] and [Hf(RBH 3 ) 4 ] complexes with substituents that attenuate volatility (R = benzyl, phenyl, mesityl, 2,4,6-triisopropylphenyl, and anthryl). 1 H and 11 B NMR spectroscopy, IR spectroscopy, and single-crystal X-ray diffraction (XRD) studies revealed metal and ligand dependent differences in the BH 3 chemical shifts that correlate to changes in M−B distances and select B–H vibrational stretching modes. The B K-edge XAS spectra of the Zr and Hf complexes yielded a pre-edge feature that was assigned as B 1s → M–H–B π* based on comparison to time-dependent density functional theory (TDDFT) calculations. The pre-edge transitions appear due to covalent mixing between boron and the metal, thereby demonstrating how B K-edge XAS can provide direct evidence of covalent three-center, two electron M–H–B bonding in borohydride complexes using boron as a spectroscopic reporter.

Hansen, Hannah M. [University of Iowa, Iowa City, ↗
DOE OSTI2024

Engineered dsRNA–protein nanoparticles for effective systemic gene silencing in plants

Long-distance transport or systemic silencing effects of exogenous biologically active RNA molecules in higher plants have not been reported. Here, we report that cationized bovine serum albumin (cBSA) avidly binds double-stranded beta-glucuronidase RNA (dsGUS RNA) to form nucleic acid–protein nanocomplexes. In our experiments with tobacco and poplar plants, we have successfully demonstrated systemic gene silencing effects of cBSA/dsGUS RNA nanocomplexes when we locally applied the nanocomplexes from the basal ends of leaf petioles or shoots. We have further demonstrated that the cBSA/dsGUS RNA nanocomplexes are highly effective in silencing both the conditionally inducible DR5-GUS gene and the constitutively active 35S-GUS gene in leaf, shoot, and shoot meristem tissues. This cBSA/dsRNA delivery technology may provide a convenient, fast, and inexpensive tool for characterizing gene functions in plants and potentially for in planta gene editing.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Agave REVEILLE1 regulates the onset and release of seasonal dormancy in Populus

Abstract Deciduous woody plants like poplar (Populus spp.) have seasonal bud dormancy. It has been challenging to simultaneously delay the onset of bud dormancy in the fall and advance bud break in the spring, as bud dormancy, and bud break were thought to be controlled by different genetic factors. Here, we demonstrate that heterologous expression of the REVEILLE1 gene (named AaRVE1) from Agave (Agave americana) not only delays the onset of bud dormancy but also accelerates bud break in poplar in field trials. AaRVE1 heterologous expression increases poplar biomass yield by 166% in the greenhouse. Furthermore, we reveal that heterologous expression of AaRVE1 increases cytokinin contents, represses multiple dormancy-related genes, and up-regulates bud break-related genes, and that AaRVE1 functions as a transcriptional repressor and regulates the activity of the DORMANCY-ASSOCIATED PROTEIN 1 (DRM1) promoter. Our findings demonstrate that AaRVE1 appears to function as a regulator of bud dormancy and bud break, which has important implications for extending the growing season of deciduous trees in frost-free temperate and subtropical regions to increase crop yield.

59 BASIC BIOLOGICAL SCIENCES↗