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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

The N‐terminal intrinsically disordered region of Ncb5or docks with the cytochrome b 5 core to form a helical motif that is of ancient origin

Abstract NADH cytochromeb 5 oxidoreductase (Ncb5or) is a cytosolic ferric reductase implicated in diabetes and neurological conditions. Ncb5or comprises cytochromeb 5 (b 5 ) and cytochromeb 5 reductase (b 5 R) domains separated by a CHORD‐Sgt1 (CS) linker domain. Ncb5or redox activity depends on proper inter‐domain interactions to mediate electron transfer from NADH or NADPH via FAD to heme. While full‐length human Ncb5or has proven resistant to crystallization, we have succeeded in obtaining high‐resolution atomic structures of theb 5 domain and a construct containing the CS andb 5 R domains (CS/b 5 R). Ncb5or also contains an N‐terminal intrinsically disordered region of 50 residues that has no homologs in other protein families in animals but features a distinctive, conserved L 34 MDWIRL 40 motif also present in reduced lateral root formation (RLF) protein in rice and increased recombination center 21 in baker's yeast, all attaching to ab 5 domain. After unsuccessful attempts at crystallizing a human Ncb5or construct comprising the N‐terminal region naturally fused to theb 5 domain, we were able to obtain a high‐resolution atomic structure of a recombinant rice RLF construct corresponding to residues 25–129 of human Ncb5or (52% sequence identity; 74% similarity). The structure reveals Trp 120 (corresponding to invariant Trp 37 in Ncb5or) to be part of an 11‐residue α‐helix (S 116 QMDWLKLTRT 126 ) packing against two of the four helices in theb 5 domain that surround heme (α2 and α5). The Trp 120 side chain forms a network of interactions with the side chains of four highly conserved residues corresponding to Tyr 85 and Tyr 88 (α2), Cys 124 (α5), and Leu 47 in Ncb5or. Circular dichroism measurements of human Ncb5or fragments further support a key role of Trp 37 in nucleating the formation of the N‐terminal helix, whose location in the N/b 5 module suggests a role in regulating the function of this multi‐domain redox enzyme. This study revealed for the first time an ancient origin of a helical motif in the N/b 5 module as reflected by its existence in a class of cytochromeb 5 proteins from three kingdoms among eukaryotes.

Biochemistry & Molecular Biology↗
DOE OSTI2020

Materials Data on U2(Mo3Se4)5 by Materials Project

U2(Mo3Se4)5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent U3+ sites. In the first U3+ site, U3+ is bonded in a body-centered cubic geometry to eight Se2- atoms. There are a spread of U–Se bond distances ranging from 2.85–3.10 Å. In the second U3+ site, U3+ is bonded in a body-centered cubic geometry to eight Se2- atoms. There are a spread of U–Se bond distances ranging from 2.85–3.09 Å. There are fifteen inequivalent Mo+2.27+ sites. In the first Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.73 Å. In the second Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.78 Å. In the third Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.76 Å. In the fourth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.76 Å. In the fifth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.76 Å. In the sixth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.77 Å. In the seventh Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.76 Å. In the eighth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.76 Å. In the ninth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.76 Å. In the tenth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.73 Å. In the eleventh Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.76 Å. In the twelfth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.53–2.75 Å. In the thirteenth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.73 Å. In the fourteenth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.76 Å. In the fifteenth Mo+2.27+ site, Mo+2.27+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.77 Å. There are twenty inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to one U3+ and three Mo+2.27+ atoms. In the second Se2- site, Se2- is bonded in a 1-coordinate geometry to one U3+ and three Mo+2.27+ atoms. In the third Se2- site, Se2- is bonded in a 1-coordinate geometry to one U3+ and three Mo+2.27+ atoms. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to three Mo+2.27+ atoms. In the fifth Se2- site, Se2- is bonded in a 1-coordinate geometry to one U3+ and three Mo+2.27+ atoms. In the sixth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the seventh Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the eighth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.27+ atoms. In the ninth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the tenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the eleventh Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the twelfth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.27+ atoms. In the thirteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the fourteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the fifteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the sixteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the seventeenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the eighteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the nineteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to one U3+ and four Mo+2.27+ atoms. In the twentieth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.27+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th2(Mo3S4)5 by Materials Project

Th2(Mo3S4)5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Th4+ sites. In the first Th4+ site, Th4+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are a spread of Th–S bond distances ranging from 2.78–3.01 Å. In the second Th4+ site, Th4+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are a spread of Th–S bond distances ranging from 2.77–3.00 Å. There are fifteen inequivalent Mo+2.13+ sites. In the first Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.59 Å. In the second Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.42–2.61 Å. In the third Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.61 Å. In the fourth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.60 Å. In the fifth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.61 Å. In the sixth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.61 Å. In the seventh Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.61 Å. In the eighth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.61 Å. In the ninth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.42–2.61 Å. In the tenth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.58 Å. In the eleventh Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.42–2.61 Å. In the twelfth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.59 Å. In the thirteenth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.59 Å. In the fourteenth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.61 Å. In the fifteenth Mo+2.13+ site, Mo+2.13+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.42–2.61 Å. There are twenty inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the third S2- site, S2- is bonded in a 4-coordinate geometry to four Mo+2.13+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the sixth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the seventh S2- site, S2- is bonded in a 4-coordinate geometry to four Mo+2.13+ atoms. In the eighth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the ninth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the tenth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the eleventh S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the twelfth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the thirteenth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the fourteenth S2- site, S2- is bonded in a 5-coordinate geometry to one Th4+ and four Mo+2.13+ atoms. In the fifteenth S2- site, S2- is bonded in a 4-coordinate geometry to four Mo+2.13+ atoms. In the sixteenth S2- site, S2- is bonded in a 4-coordinate geometry to one Th4+ and three Mo+2.13+ atoms. In the seventeenth S2- site, S2- is bonded in a 4-coordinate geometry to one Th4+ and three Mo+2.13+ atoms. In the eighteenth S2- site, S2- is bonded in a 4-coordinate geometry to one Th4+ and three Mo+2.13+ atoms. In the nineteenth S2- site, S2- is bonded in a 6-coordinate geometry to three Mo+2.13+ atoms. In the twentieth S2- site, S2- is bonded in a 4-coordinate geometry to one Th4+ and three Mo+2.13+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Mn(Pt 1–x Pd x ) 5 P: Isovalent tuning of Mn-sublattice magnetic order

Here, e report the growth and characterization of MnPd 5 P, a rare-earth-free ferromagnet, with T C ≈ 295 K and planar anisotropy, and conduct a substitutional study with its antiferromagnetic analogue MnPt 5 P. We provide a solution route to grow large single crystals of MnPd 5 P and the series Mn(Pt 1–x Pd x ) 5 P by adding Mn into Pd-P and (Pt 1–x Pd x )-P based melts. All compounds in the family adopt the layered anti-CeCoIn5 type structure with the space group P4/mmm, and EDS and X-ray diffraction results indicate that MnPt 5 P and MnPd 5 P form a complete solid solution. Based on measurements of the temperature- and field-dependent magnetization and resistance, we construct a temperature-composition (T-x) phase diagram for Mn(Pt 1–x Pd x ) 5 P and demonstrate that the initial antiferromagnetic order found in MnPt 5 P is extraordinarily sensitive to Pd substitution. At low Pd fractions (x < 0.010), the single antiferromagnetic transition in pure MnPt 5 P splits into a higher temperature ferromagnetic transition followed first, upon cooling, by a lower temperature ferromagnetic to antiferromagnetic transition and then by a re-entrant antiferromagnetic to ferromagnetic transition at even lower temperatures. The antiferromagnetic region makes up a bubble phase that persists up to x ≈ 0.008-0.009 for T ≈ 150 K, with all samples x < 0.008 recovering their initial ferromagnetic state upon further cooling to base temperature. Over the same low substitution range we find a non-monotonic change in the room temperature value of the unit cell volume, further suggesting that pure MnPt 5 P is very close to an instability. Once x > 0.010, Mn(Pt 1–x Pd x ) 5 P undergoes a only single transition into the ferromagnetic phase. The Curie temperature initially increases rapidly with x, rising from T C ≈ 197 K at x = 0.013 to a maximum of T C ≈ 312 K for x ≈ 0.62, and then falling back to T C ≈ 295 K for pure MnPd 5 P (x = 1.00). Given that Pt and Pd are isoelectronic, this work raises questions as to the origin of the extreme sensitivity of the magnetic ground state in MnPt 5 P upon introducing Pd.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Chemical Bonding Governs Complex Magnetism in MnPt 5 P

Subtle changes in chemical bonds may result in dramatic revolutions in magnetic properties in solid-state materials. MnPt 5 P, a derivative of the rare-earth-free ferromagnetic MnPt 5 As, was discovered and is presented in this work. Specifically, MnPt 5 P was synthesized, and its crystal structure and chemical composition were characterized by X-ray diffraction as well as energy-dispersive X-ray spectroscopy. Accordingly, MnPt 5 P crystallizes in the layered tetragonal structure with the space group P4/mmm (No. 123), in which the face-shared Mn@Pt 12 polyhedral layers are separated by P layers. In contrast to the ferromagnetism observed in MnPt 5 As, the magnetic properties measurements on MnPt 5 P show antiferromagnetic ordering occurs at ~188 K with a strong magnetic anisotropy in and out of the ab-plane. Moreover, a spin-flop transition appears when a high magnetic field is applied. An A-type antiferromagnetic structure was obtained from the analysis of powder neutron diffraction (PND) patterns collected at 150 and 9 K. Calculated electronic structures imply that hybridization of Mn-3d and Pt-5d orbitals is critical for both the structural stability and observed magnetic properties. Semiempirical molecular orbitals calculations on both MnPt 5 P and MnPt 5 As indicate that the lack of 4p character on the P atoms at the highest occupied molecular orbital (HOMO) in MnPt 5 P may cause the different magnetic behavior in MnPt 5 P compared to MnPt 5 As. The discovery of MnPt 5 P, along with our previously reported MnPt5As, parametrizes the end points of a tunable system to study the chemical bonding which tunes the magnetic ordering from ferromagnetism to antiferromagnetism with the strong spin–orbit coupling (SOC) effect.

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

Novel insights into the role of translesion synthesis polymerase in DNA incorporation and bypass of 5-fluorouracil in colorectal cancer

Abstract 5-Fluorouracil (5-FU) is the first-line chemotherapeutic agent in colorectal cancer, and resistance to 5-FU easily emerges. One of the mechanisms of drug action and resistance of 5-FU is through DNA incorporation. Our quantitative reverse-transcription PCR data showed that one of the translesion synthesis (TLS) DNA polymerases, DNA polymerase η (polη), was upregulated within 72 h upon 5-FU administration at 1 and 10 μM, indicating that polη is one of the first responding polymerases, and the only TLS polymerase, upon the 5-FU treatment to incorporate 5-FU into DNA. Our kinetic studies revealed that 5-fluoro-2′-deoxyuridine triphosphate (5FdUTP) was incorporated across dA 41 and 28 times more efficiently than across dG and across inosine, respectively, by polη indicating that the mutagenicity of 5-FU incorporation is higher in the presence of inosine and that DNA lesions could lead to more mutagenic incorporation of 5-FU. Our polη crystal structures complexed with DNA and 5FdUTP revealed that dA:5FdUTP base pair is like dA:dTTP in the active site of polη, while 5FdUTP adopted 4-enol tautomer in the base pairs with dG and HX increasing the insertion efficiency compared to dG:dTTP for the incorrect insertions. These studies confirm that polη engages in the DNA incorporation and bypass of 5-FU.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Nevada National Security Site 2019 Waste Management Monitoring Report Area 3 and Area 5 Radioactive Waste Management Sites

Environmental monitoring data are collected at and around the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) within the Nevada National Security Site (NNSS). This report summarizes the 2019 environmental data to provide an overall evaluation of RWMS performance and to support environmental compliance and performance assessment (PA) activities. Some of these data (e.g., radiation exposure, air, and groundwater) are presented in other reports (Mission Support and Test Services, LLC 2019, 2020a, 2020b). Direct radiation monitoring data indicate exposure levels at the Area 3 and Area 5 RWMSs are within the range of background levels measured at the NNSS. Slightly elevated exposure levels outside the Area 3 RWMS are attributed to nearby historical aboveground nuclear weapons tests. Air monitoring data at the Area 3 and Area 5 RWMSs show that tritium concentrations in water vapor and americium and plutonium concentrations in air particles are below Derived Concentration Standards for these radionuclides. Groundwater monitoring data indicate the groundwater in the uppermost aquifer beneath the Area 5 RWMS is not impacted by RWMS operations. Results of groundwater analysis from wells around the Area 5 RWMS are below established investigation levels. Leachate samples collected from the leachate collection systems at the Area 5 mixed low-level waste disposal unit are below established contaminant regulatory limits. During 2019, precipitation at the Area 3 RWMS was 77 percent above average, and precipitation at the Area 5 RWMS was 69 percent above average. Water balance measurements indicate that evapotranspiration from the vegetated weighing lysimeter at the Area 5 RWMS dries the soil and prevents downward percolation of precipitation more effectively than evaporation as measured from the bare-soil weighing lysimeter. Vadose zone monitoring in the Area 3 and Area 5 RWMS soil covers shows no evidence of precipitation percolating through the covers to the waste. Moisture from precipitation did not percolate below 120 centimeters (3.9 feet [ft]) in the vegetated final cover on the U-3ax/bl disposal unit at the Area 3 RWMS during 2019. There was no drainage through 2.4 meters (8 ft) of soil as indicated from the Area 3 drainage lysimeters that received only natural precipitation. At the Area 3 RWMS, which received three times the natural precipitation, 57 percent of the applied precipitation and irrigation drained from the bare-soil drainage lysimeter. All 2019 monitoring data indicate that the Area 3 and Area 5 RWMSs are performing within expectations of the model and parameter assumptions for the facilities’ PAs.

2019↗
DOE OSTI2021

Defect–Concentration–Mediated T–Nb 2 O 5 Anodes for Durable and Fast–Charging Li–Ion Batteries

Metastable orthorhombic niobium pentoxide (T-Nb 2 O 5 ) is a promising anode to fulfill the requirements for high-rate Li-ion batteries (LIBs). Stoichiometric T-Nb 2 O 5 is plagued by low electric conductivity and particle pulverization after repeated charge/discharge processes. In this work, oxygen vacancies are implanted into T-Nb 2 O 5 particles via acid immersion of Nb 2 O 5 ·nH 2 O with the formation of Lewis acid sites. The multiple characterizations and simulations reveal the lengthening of Nb–O bonds, and the transformation from NbO 7 pentagonal bipyramids and NbO 6 tetragonal bipyramids in T-Nb 2 O 5–x . The enrichment of oxygen vacancies endows T-Nb 2 O 5–x with higher electric conductivity, better electrochemical kinetics, larger pseudocapacitive contribution. O-doped graphitic C 3 N 4 is creatively proposed as a trace oxygen pump to repair excessive oxygen vacancies, and it also serves as a sacrifice template for Nb 2 O 5–x growth to construct a porous and monolithic electrode network. Defect-modulated Nb 2 O 5–x displays extraordinary cycling stability (164 mAh g –1 at 5 C after 1100 cycles), high capacity retention (104 mAh g –1 ) at an ultrahigh rate (25 C), and large areal capacity (0.74 mAh cm –2 ) under high mass loading (4 mg cm –2 ). The practical prospect is proved by Nb 2 O 5–x /LiNi 0.8 Co 0.1 Mn 0.1 O 2 full cells with high average platform (2.12 V) and high specific capacity (229 mAh g –1 ). Finally, the oxygen-defect modulation strategy on oxide anodes provides an alternative solution to fast-charging and durable LIBs.

25 ENERGY STORAGE↗
DOE OSTI2024

Linking NH$^+_4$ motion to magnetism in molecular multiferroic (NH 4 ) 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)]: A neutron vibrational spectroscopy study

Here, we present a neutron vibrational spectroscopy study to investigate the influence of NH$^+_4$ motion on the magnetism in [(NH 4 ) 1–x K x ] 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)]. The parent compounds, (NH 4 ) 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)] (x = 0) and K 2 ⁡[FeCl 5 ⁢(H 2 ⁢O)]⁢(x = 1) are isostructural at room temperature, yet displaying drastically different magnetic and multiferroic behavior. K 2 ⁡[FeCl 5 ⁢(H 2 ⁢O)] is nonmultiferroic with type-A collinear antiferromagnetic structure below T N ≈ 14.06 K, whereas (NH 4 ) 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)] is a type-II multiferroic with incommensurate cycloidal spin structure below T FE ≈ 6.8 K. A recent study of the dielectric, structure, and magnetic properties in the mixed [(NH 4 ) 1–x ⁢K x ] 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)] shows that a small amount of potassium substitution to replace NH$^+_4$ transforms the spin structure from incommensurate cycloidal (x ≤ 0.06) into commensurate collinear antiferromagnetic (x ≥ 0.15), indicating NH$^+_4$ is essential to the emergent phenomena observed in this molecular multiferroic compound. Our vibrational spectroscopy study reveals that NH$^+_4$ libration and torsion motion exhibit substantial temperature dependence at low temperatures. The intensity of NH$^+_4$ libration and torsion modes increases slightly at 5 K in comparison with data at 25 K behaving like a magnon, indicating that they are coupled to the magnetism in (NH 4 ) 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)]. Comparing data of x=0, 0.06, 0.09, and 0.15 samples further illustrates that the strength of the increased signal in NH$^+_4$ libration mode is very sensitive to potassium concentration. The signal diminishes quickly with increasing potassium concentration and vanishes in the x = 0.15 sample corresponding to the magnetic structure change for x ≥ 0.15. The results directly link the anomalous behavior in NH$^+_4$ libration motion to the magnetism in [(NH 4 ) 1–x ⁢K x ] 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)], providing new insights into the crucial role NH$^+_4$ plays in the coupled phenomena in (NH 4 ) 2 ⁢[FeCl 5 ⁢(H 2 ⁢O)]. The unique information opens a new door to go through in searching for new multifunctional materials by incorporation of NH 4 via a material-by-design approach.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Suppressed paramagnetism in amorphous Ta 2 O 5 − x oxides and its link to superconducting-qubit performance

Amorphous-oxide layers in thin-film capacitors are linked to reduced transmon-qubit T 1 coherence times. Ta -based capacitors outperform Nb -based ones, suggesting that amorphous Ta 2 O 5 − x is less lossy than Nb 2 O 5 − x . We investigate the microscopic features of these amorphous oxides using ab initio molecular dynamics and density functional theory, revealing the origins of the superior performance of Ta 2 O 5 − x . We establish that oxygen deficiency is less likely to occur in amorphous Ta 2 O 5 − x than in Nb 2 O 5 − x for 0 ≤ x ≤ 0.25 and that for a given oxygen deficiency x , metal Ta — Ta bond formation is enhanced. Such bonds, which are accommodated by structural flaws in the amorphous network, capture electrons better than in amorphous Nb 2 O 5 − x . These thermochemical differences quench or highly suppress magnetic moments in amorphous Ta 2 O 5 − x and eliminate a potential source of quasiparticles and magnetic flux noise. We also show that hyperfine couplings between Nb nuclei and local magnetic moments in Nb 2 O 5 − x can form “two-level systems” (TLSs) or “two-level fluctuators” with energy splittings of 100–1000 MHz or higher. This reveals a TLS mechanism in amorphous Nb 2 O 5 − x oxide layers that is likely inactive in Ta 2 O 5 − x . Our work provides a fundamental understanding of the materials chemistry and limitations imposed by native oxides of superconducting qubits that can be used to guide materials selection and processing.

Pritchard, P. Graham [Northwestern U.] (ORCID:0000↗
DOE OSTI2024

Metabolic Engineering of Nonmodel Yeast Issatchenkia orientalis SD108 for 5–Aminolevulinic Acid Production

Biological production of 5-aminolevulinic acid (5-ALA) has received growing attention over the years. However, there is the tradeoff between 5-ALA biosynthesis and cell growth because the fermentation broth will become acidic due to the production of 5-ALA. To address this limitation, we engineered an acid-tolerant yeast, Issatchenkia orientalis SD108, for 5-ALA production. We first discovered that the cell growth rate of I. orientalis SD108 was boosted by 5-ALA and its endogenous ALA synthetase (ALAS) showed higher activity than those homologs from other yeasts. The titer of 5-ALA was improved from 28 mg/L to 120-, 150-, and 300 mg/L, by optimizing plasmid design, overexpressing a transporter, and increasing gene copy number, respectively. After redirecting the metabolic flux using the pyruvate decarboxylase (PDC) knockout strain (SD108ΔPDC) and culturing with urea, we increased the titer of 5-ALA to 510 mg/L, a 13-fold enhancement, proving the importance of the newly identified IoALAS with higher activity and the strategic selection of nitrogen sources for knockout strains. This study demonstrates the acid-tolerant I. orientalis SD108ΔPDC has a high potential for 5-ALA production at a large scale in the future.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Why Are 5-Thioglycopyranosyl Donors More Axially Selective than their Glycopyranosyl Counterparts? A Low and Variable Temperature NMR Spectroscopy and Computational Study

5-Thioglycopyranosyl donors differ in reactivity and selectivity from simple glycopyranosyl donors. An extensive study has been conducted on the nature and stability of the reactive intermediates generated on the activation of per-O-acetyl and per-O-methyl 5-thioglucopyranosyl donors and the corresponding glucopyranosyl donors. Variable temperature nuclear magnetic resonance (NMR) studies with per-O-methylated or per-O-acetyl glycosyl sulfoxides and trichloroacetimidates on activation with trifluoromethanesulfonic anhydride or trimethylsilyl triflate are reported. These show that following initial adduct formation with the promoter conversion of the 5-thioglucopyranosyl donors to the 5-thioglucopyranosyl triflates requires higher temperatures than that of the glucopyranosyl donors to the glucopyranosyl triflates. It is demonstrated that neighboring group participation is a less important phenomenon for the peracetylated thioglucosyl donors than for the peracetylated glucosyl donors. A simple thiocarbenium ion was generated by protonation of 2,3-dihydro-4H-thiopyran at low temperature and characterized by NMR spectroscopy. However, the corresponding 5-thioglucopyranosyl thenium ions were not observed in any of the NMR studies of the 5-thiopyranosyl donors: the electron-withdrawing C–O bonds around the thiopyranoside core discourage thiocarbenium ion formation, just as they discourage oxocarbenium ion formation. Density functional theory (DFT) calculations reveal the tetrahydrothiopyranyl thiocarbenium ion to be approximately 2.5 kcal/mol lower in energy than the corresponding tetrahydropyranyl oxocarbenium ion relative to the corresponding covalent triflates. However, the computations reveal a 5.8 kcal/mol activation barrier for conversion of the tetrahydrothiopyranyl triflate to the thiocarbenium ion, while formation of the oxocarbenium ion–triflate ion pair from tetrahydropyranyl triflate requires only 2.6 kcal·mol –1 . Overall, the greater axial selectivity of 5-thioglycopyranosyl donors compared to analogous glycopyranosyl donors derives from (i) the lower kinetic reactivity necessitating higher reaction temperatures, (ii) the greater stability of the thiocarbenium ion over the oxocarbenium ion facilitating equilibration under thermodynamic conditions, (iii) the greater magnitude of the anomeric effect in the 5-thiosugars, and (iv) decreased neighboring group participation in the per-esterified 5-thiosugars.

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

Relationship and distribution of Salmonella enterica serovar I 4,[5],12:i:- strain sequences in the NCBI Pathogen Detection database

Background: Of the > 2600 Salmonella serovars, Salmonella enterica serovar I 4,[5],12:i:- (serovar I 4,[5],12:i:-) has emerged as one of the most common causes of human salmonellosis and the most frequent multidrug-resistant (MDR; resistance to ≥3 antimicrobial classes) nontyphoidal Salmonella serovar in the U.S. Serovar I 4,[5],12:i:- isolates have been described globally with resistance to ampicillin, streptomycin, sulfisoxazole, and tetracycline (R-type ASSuT) and an integrative and conjugative element with multi-metal tolerance named Salmonella Genomic Island 4 (SGI-4). Results: We analyzed 13,612 serovar I 4,[5],12:i:- strain sequences available in the NCBI Pathogen Detection database to determine global distribution, animal sources, presence of SGI-4, occurrence of R-type ASSuT, frequency of antimicrobial resistance (AMR), and potential transmission clusters. Genome sequences for serovar I 4,[5],12:i:- strains represented 30 countries from 5 continents (North America, Europe, Asia, Oceania, and South America), but sequences from the United States (59%) and the United Kingdom (28%) were dominant. The metal tolerance island SGI-4 and the R-type ASSuT were present in 71 and 55% of serovar I 4,[5],12:i:- strain sequences, respectively. Sixty-five percent of strain sequences were MDR which correlates to serovar I 4,[5],12:i:- being the most frequent MDR serovar. The distribution of serovar I 4,[5],12:i:- strain sequences in the NCBI Pathogen Detection database suggests that swine-associated strain sequences were the most frequent food-animal source and were significantly more likely to contain the metal tolerance island SGI-4 and genes for MDR compared to all other animal-associated isolate sequences. Conclusions: Our study illustrates how analysis of genomic sequences from the NCBI Pathogen Detection database can be utilized to identify the prevalence of genetic features such as antimicrobial resistance, metal tolerance, and virulence genes that may be responsible for the successful emergence of bacterial foodborne pathogens.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Integration of polyurethane meniscus scaffold during ACL revision is not reliable at 5 years despite favourable clinical outcome

Abstract Purpose The aim of this study was to evaluate the clinical outcome at 5‐year follow‐up of a one‐step procedure combining anterior cruciate ligament (ACL) reconstruction and partial meniscus replacement using a polyurethane scaffold for the treatment of symptomatic patients with previously failed ACL reconstruction and partial medial meniscectomy. Moreover, the implanted scaffolds have been evaluated by MRI protocol in terms of morphology, volume, and signal intensity. Methods Twenty patients with symptomatic knee laxity after failed ACL reconstruction and partial medial meniscectomy underwent ACL revision combined with polyurethane‐based meniscal scaffold implant. Clinical assessment at 2‐ and 5‐year follow‐ups included VAS, Tegner Activity Score, International Knee Documentation Committee (IKDC), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Lysholm Score. MRI evaluation of the scaffold was performed according to the Genovese scale with quantification of the scaffold’s volume at 1‐ and 5‐year follow‐ups. Results All scores revealed clinical improvement as compared with the preoperative values at the 2‐ and 5‐year follow‐ups. However, a slight, but significant reduction of scores was observed between 2 and 5 years. Concerning the MRI assessment, a significant reduction of the scaffold’s volume was observed between 1 and 5 years. Genovese Morphology classification at 5 years included two complete resorptions (Type 3) and all the remaining patients had irregular morphology (Type 2). With regard to the Genovese Signal at the 5‐year follow‐up, three were classified as markedly hyperintense (Type 1), 15 as slightly hyperintense (Type 2), and two as isointense (Type 1). Conclusion Simultaneous ACL reconstruction and partial meniscus replacement using a polyurethane scaffold provides favourable clinical outcomes in the treatment of symptomatic patients with previously failed ACL reconstruction and partial medial meniscectomy at 5 years. However, MRI evaluation suggests that integration of the scaffold is not consistent. Level of evidence Level IV.

Pereira, Hélder↗
DOE OSTI2024

First-order structural phase transition at low temperature in GaPt 5 P and its rapid enhancement with pressure

Single crystals of X Pt 5 ⁢P (X = Al, Ga, and In), belonging to the 1-5-1 family of compounds, were grown from a Pt-P solution at high temperatures, and measurements of the ambient pressure, temperature-dependent magnetization, resistivity, and x-ray diffraction were made. Additionally, the ambient-pressure Hall resistivity and temperature-dependent resistance under pressure were measured on GaPt 5 ⁢P. All three compounds have a tetragonal P4/mmm crystal structure at room temperature with metallic transport and weak diamagnetism over the 2–300 K temperature range. Surprisingly, at ambient pressure, both the transport and magnetization measurements on GaPt 5 ⁢P show a steplike feature in the 70–90 K region, suggesting a possible structural phase transition. Neither AlPt 5 ⁢P nor InPt 5 ⁢P have any signatures of a phase transition in their temperature-dependent electrical resistance and magnetization data. Both the hysteretic nature and sharpness of the features in the GaPt 5 ⁢P data suggest that the transition is first-order. Further, single-crystal x-ray diffraction measurements provided further details of the structural transition with a possibility of a crystal symmetry different from P⁢4/mmm below the transition temperature. The transition is characterized by anisotropic changes in the lattice parameters and a volume collapse with respect to the high-temperature tetragonal crystal structure. Furthermore, satellite peaks are observed at two distinct and nonequivalent wave vectors (0, 0, 0.5) and (0.5, 0.5, 0.5), and density functional theory calculations present phonon softening, especially at (0.5, 0.5, 0.5), as a possible driving mechanism. Additionally, we find that the structural transition temperature increases rapidly with increasing pressure, reaching room temperature by ~2.2 GPa, highlighting the high degree of pressure sensitivity of GaPt 5 ⁢P and fragile nature of its room-temperature structure. Even though the volume collapse and extreme pressure sensitivity suggest chemical pressure should drive a similar structural change in AlPt 5⁢ P, where both unit-cell dimensions and volume are smaller, its structure is found to be the same as that of the room-temperature GaPt 5 ⁢P. Overall, GaPt 5 ⁢P stands out as a sole member of the 1-5-1 family of compounds for which a temperature-driven structural change has been observed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on K3(VS2)5 by Materials Project

K3(VS2)5 is Orthorhombic Perovskite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of K–S bond distances ranging from 3.12–3.22 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of K–S bond distances ranging from 3.08–3.22 Å. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to six S2- atoms. There are four shorter (3.16 Å) and two longer (3.18 Å) K–S bond lengths. There are five inequivalent V+3.40+ sites. In the first V+3.40+ site, V+3.40+ is bonded to six S2- atoms to form edge-sharing VS6 octahedra. There are a spread of V–S bond distances ranging from 2.36–2.46 Å. In the second V+3.40+ site, V+3.40+ is bonded to six S2- atoms to form edge-sharing VS6 octahedra. There are a spread of V–S bond distances ranging from 2.37–2.45 Å. In the third V+3.40+ site, V+3.40+ is bonded to six S2- atoms to form edge-sharing VS6 octahedra. There are a spread of V–S bond distances ranging from 2.31–2.52 Å. In the fourth V+3.40+ site, V+3.40+ is bonded to six S2- atoms to form edge-sharing VS6 octahedra. There are a spread of V–S bond distances ranging from 2.33–2.51 Å. In the fifth V+3.40+ site, V+3.40+ is bonded to six S2- atoms to form edge-sharing VS6 octahedra. There are a spread of V–S bond distances ranging from 2.31–2.51 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted square pyramidal geometry to two K1+ and three V+3.40+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms. In the sixth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one K1+ and three V+3.40+ atoms. In the seventh S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one K1+ and three V+3.40+ atoms. In the eighth S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms. In the ninth S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms. In the tenth S2- site, S2- is bonded in a 5-coordinate geometry to two K1+ and three V+3.40+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na7Cu4(AsO4)5 by Materials Project

Na7Cu4(AsO4)5 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are seven inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.89 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.81 Å. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.27–2.83 Å. In the fourth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.24–2.72 Å. In the fifth Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.39–2.89 Å. In the sixth Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–3.00 Å. In the seventh Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.47–2.97 Å. There are four inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to five O2- atoms to form CuO5 trigonal bipyramids that share corners with five AsO4 tetrahedra. There are a spread of Cu–O bond distances ranging from 1.92–2.21 Å. In the second Cu2+ site, Cu2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cu–O bond distances ranging from 1.91–2.58 Å. In the third Cu2+ site, Cu2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cu–O bond distances ranging from 1.93–2.19 Å. In the fourth Cu2+ site, Cu2+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Cu–O bond distances ranging from 1.90–2.80 Å. There are five inequivalent As5+ sites. In the first As5+ site, As5+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.70 Å) and three longer (1.73 Å) As–O bond length. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one CuO5 trigonal bipyramid. There are a spread of As–O bond distances ranging from 1.69–1.76 Å. In the third As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one CuO5 trigonal bipyramid. There are a spread of As–O bond distances ranging from 1.71–1.75 Å. In the fourth As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one CuO5 trigonal bipyramid. There are a spread of As–O bond distances ranging from 1.71–1.75 Å. In the fifth As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two equivalent CuO5 trigonal bipyramids. There are a spread of As–O bond distances ranging from 1.71–1.74 Å. There are twenty inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one As5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Cu2+, and one As5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+, one Cu2+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Cu2+, and one As5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to four Na1+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Cu2+, and one As5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+, one Cu2+, and one As5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Cu2+, and one As5+ atom. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Cu2+, and one As5+ atom. In the tenth O2- site, O2- is bonded to two Na1+, one Cu2+, and one As5+ atom to form distorted corner-sharing ONa2CuAs trigonal pyramids. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Cu2+, and one As5+ atom. In the twelfth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+, one Cu2+, and one As5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Cu2+, and one As5+ atom. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to four Na1+, one Cu2+, and one As5+ atom. In the fifteenth O2- site, O2- is bonded to two Na1+, one Cu2+, and one As5+ atom to form distorted corner-sharing ONa2CuAs tetrahedra. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+, one Cu2+, and one As5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Cu2+, and one As5+ atom. In the eighteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Cu2+, and one As5+ atom. In the nineteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+, one Cu2+, and one As5+ atom. In the twentieth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+, one Cu2+, and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

High-pressure synthesis, crystal structure, and magnetic properties of the Shastry-Sutherland-lattice oxides BaL n 2 ZnO 5 (L n = Pr, Sm, Eu)

BaPr 2 ZnO 5 , BaSm 2 ZnO 5 , and BaEu 2 ZnO 5 – a series of 4f magnetic insulators comprising the Shastry-Sutherland lattice – were synthesized via a solid-state reaction under high-pressure and high-temperature conditions. The magnetic behaviors are well characterized by the localized 4f electrons of each Ln 3+ (= Pr, Sm, Eu) under the influence of the crystal-electric field of the surrounding ions. The magnetic susceptibility and heat capacity measurements of BaPr 2 ZnO 5 (Pr 3+ ; 4f 2 3 H 4 ) indicate the splitting of the ground state J-multiplet due to the crystal-electric field. BaSm 2 ZnO 5 (Sm 3+ ; 4f 5 6 H 5/2 ) is a strong Van Vleck paramagnet, while BaEu 2 ZnO 5 is non-magnetic due to the 7 F 0 ground state (Eu 3+ ; 4f 6 7 F 0 ). The series of new oxides enriches a group of the Shastry-Sutherland lattice materials and helps to develop a range of two-dimensional quantum materials.

36 MATERIALS SCIENCE↗