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DOE OSTI2021

High Ammonia Adsorption in MFM-300 Materials: Dynamics and Charge Transfer in Host–Guest Binding

Ammonia (NH 3 ) is a promising energy resource owing to its high hydrogen density. However, its widespread application is restricted by the lack of efficient and corrosion-resistant storage materials. In this work, we report high NH 3 adsorption in a series of robust metal-organic framework (MOF) materials, MFM-300(M) (M = Fe, V, Cr, In). MFM-300(M) (M = Fe, V III , Cr) show fully reversible capacity for >20 cycles, reaching capacities of 16.1, 15.6, and 14.0 mmol g -1 , respectively, at 273 K and 1 bar. Under the same conditions, MFM-300(V IV ) exhibits the highest uptake among this series of MOFs of 17.3 mmol g -1 . In situ neutron powder diffraction, single-crystal X-ray diffraction, and electron paramagnetic resonance spectroscopy confirm that the redox-active V center enables host-guest charge transfer, with V IV being reduced to V III and NH 3 being oxidized to hydrazine (N 2 H 4 ). A combination of in situ inelastic neutron scattering and DFT modeling has revealed the binding dynamics of adsorbed NH 3 within these MOFs to afford a comprehensive insight into the application of MOF materials to the adsorption and conversion of NH 3 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Phase Stability and Electrochemical Performance of La-Site-Doped Li6La3Zr0.5Nb0.5Ta0.5Hf0.5O12 High-Entropy Garnets

We investigate La-site substitution in the high-entropy garnet Li6La3Zr0.5Nb0.5Ta0.5Hf0.5O12 (LLZNTH) using Ba2+, Sr2+, and Sm3+ to elucidate how dopant governs phase stability, Li-site distribution, and electrochemical behavior. X-ray diffraction shows that Sr2+ is incorporated homogeneously into the garnet lattice, whereas the larger Ba2+ and smaller Sm3+ ions partially exceed the structural tolerance, generating secondary phases. Nevertheless, the Sm-doped composition (x = 0.05) exhibits the highest room-temperature ionic conductivity (2.7 × 10–4 S cm–1). Neutron powder diffraction reveals that Sm substitution drives a redistribution of Li+ from the tetrahedral 24 d sites into the higher-mobility 96 h positions, enhancing the connectivity of the three-dimensional Li-ion migration network. A Sm-doping series (x = 0.01–0.05) further shows that only sufficiently high Sm levels induce this redistribution, whereas lower concentrations retain Li arrangements similar to the undoped garnet. Critical current density measurements demonstrate that La-site dopants also influence interfacial stability against Li metal, underscoring a trade-off between bulk transport enhancement and mechanical robustness. Collectively, these findings reveal that in high-entropy garnets improved ionic conductivity can originate not only from phase-pure structures but also from targeted modification of the Li sublattice, even when accompanied by secondary phases, offering a compositional design principle for garnet electrolytes.

Li, Chang [Mechanical Engineering, School of Scien↗

DOE OSTI2018

Double-Crystal Rocking Curve Simulation Using 2D Spectral Angular Diagrams of X-Ray Radiation

A new approach to numerical simulation of double-crystal rocking curves is proposed. This approach is based on the use of experimental spectral angular diagrams of X-ray intensity distribution. Special calculation algorithms, which take into account the instrumental function of X-ray diffractometer and possible effects of dispersion and Bragg reflection asymmetry, have been developed and applied. A specific feature of the proposed approach is the possibility of visualizing the 2D spectral angular diagram of X-ray beam after its interaction with each element of the scheme. The approach makes it possible to perform calculations for a wide range of radiation sources (from an X-ray tube with any anode to a synchrotron radiation source) and X-ray optical elements (slits and monochromators). A comparison of simulation results and experimental data for a Si(110) crystal sample has confirmed adequacy of the proposed approach and its applicability for simulating diffraction patterns recorded in real experiments.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2023

Studies on the structure and the magnetic properties of high-entropy spinel oxide (MgMnFeCoNi)Al 2 O 4

The study of high-entropy materials has attracted enormous interest since they could show new functional properties that are not observed in their related parent phases. Here, we report single crystal growth, structure, thermal transport, and magnetic property studies on a novel high-entropy oxide with the spinel structure (MgMnFeCoNi)Al 2 O 4 . We have successfully grown high-quality single crystals of this high-entropy oxide using the optical floating zone growth technique for the first time. The sample was confirmed to be a phase pure high-entropy oxide using x-ray diffraction and energy-dispersive spectroscopy. Through magnetization measurements, we found (MgMnFeCoNi)Al 2 O 4 exhibits a cluster spin glass state, though the parent phases show either antiferromagnetic ordering or spin glass states. Furthermore, we also found that (MgMnFeCoNi)Al 2 O 4 has much greater thermal expansion than its CoAl 2 O 4 parent compound using high resolution neutron Larmor diffraction. We further investigated the structure of this high-entropy material via Raman spectroscopy and extended x-ray absorption fine structure spectroscopy (EXAFS) measurements. From Raman spectroscopy measurements, we observed (MgMnFeCoNi)Al 2 O 4 to display a combination of the active Raman modes in its parent compounds with the modes shifted and significantly broadened. This result, together with the varying bond lengths probed by EXAFS, reveals severe local lattice distortions in this high-entropy phase. Additionally, we found a substantial decrease in thermal conductivity and suppression of the low temperature thermal conductivity peak in (MgMnFeCoNi)Al 2 O 4 , consistent with the increased lattice defects and strain. These findings advance the understanding of the dependence of thermal expansion and transport on the lattice distortions in high-entropy materials.

36 MATERIALS SCIENCE↗

NASA NTRS2003

Application of Powder Diffraction Methods to the Analysis of Short- and Long-Range Atomic Order in Nanocrystalline Diamond and SiC: The Concept of the Apparent Lattice Parameter (alp)

Two methods of the analysis of powder diffraction patterns of diamond and SiC nanocrystals are presented: (a) examination of changes of the lattice parameters with diffraction vector Q ('apparent lattice parameter', alp) which refers to Bragg scattering, and (b), examination of changes of inter-atomic distances based on the analysis of the atomic Pair Distribution Function, PDF. Application of these methods was studied based on the theoretical diffraction patterns computed for models of nanocrystals having (i) a perfect crystal lattice, and (ii), a core-shell structure, i.e. constituting a two-phase system. The models are defined by the lattice parameter of the grain core, thickness of the surface shell, and the magnitude and distribution of the strain field in the shell. X-ray and neutron experimental diffraction data of nanocrystalline SiC and diamond powders of the grain diameter from 4 nm up to micrometers were used. The effects of the internal pressure and strain at the grain surface on the structure are discussed based on the experimentally determined dependence of the alp values on the Q-vector, and changes of the interatomic distances with the grain size determined experimentally by the atomic Pair Distribution Function (PDF) analysis. The experimental results lend a strong support to the concept of a two-phase, core and the surface shell structure of nanocrystalline diamond and SiC.

Palosz, B.↗

DOE OSTI2019

Crystal fields and magnetic structure of the Ising antiferromagnet Er 3 Ga 5 O 12

Rare-earth garnets are an exciting playground for studying the exotic magnetic properties of the frustrated hyperkagome lattice. In this paper we present a comprehensive study of the single ion and collective magnetic properties of the garnet Er 3 Ga 5 O 12 . Using inelastic neutron scattering, we find a crystal-field ground-state doublet for Er 3 + with strong Ising anisotropy along local [100] axes. Magnetic susceptibility and heat-capacity measurements provide evidence for long-range magnetic ordering with T N = 0.8 K , and no evidence for residual entropy is found when cooling through the ordering transition. Neutron powder diffraction reveals that the ground-state spin configuration corresponds to the six-sublattice, Ising antiferromagnetic state ( Γ 3 ) common to many of the rare-earth garnets. However, we also found that μ SR appears to be insensitive to the ordering transition in this material, in which a low-temperature relaxation plateau was observed with no evidence of spontaneous muon precession. The combined muon and neutron results may be indicative of a dynamical ground state with a relatively long correlation time. Despite this potential complication, our work indicates that Er 3 Ga 5 O 12 is an excellent model system for studying the complex metamagnetism expected for a multiaxis antiferromagnet.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Revisiting the Kitaev material candidacy of Ir 4 + double perovskite iridates

Quantum magnets with significant bond-directional Ising interactions, so-called Kitaev materials, have attracted tremendous attention recently in the search for exotic spin liquid states. Here we present a comprehensive set of measurements that enables us to investigate the crystal structures, Ir 4+ single-ion properties, and magnetic ground states of the double perovskite iridates La 2 BIrO 6 (B = Mg, Zn) and A 2 CeIrO 6 (A = Ba, Sr) with a large nearest-neighbor distance >5 angstrom between Ir 4+ ions. Our neutron powder diffraction data on Ba 2 CeIrO 6 can be refined in the cubic space group Fm$\overline{3}$m, while the other three systems are characterized by weak monoclinic structural distortions. Despite the variance in the noncubic crystal field experienced by the Ir 4+ ions in these materials, x-ray absorption spectroscopy and resonant inelastic x-ray scattering are consistent with J eff = 1/2 moments in all cases. Furthermore, neutron scattering and resonant magnetic x-ray scattering show that these systems host A-type antiferromagnetic order. These electronic and magnetic ground states are consistent with expectations for face-centered-cubic magnets with significant antiferromagnetic Kitaev exchange, which indicates that spacing magnetic ions far apart may be a promising design principle for uncovering additional Kitaev materials

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2022

NaCo 2 (SeO 3 ) 2 (OH): competing magnetic ground states of a new sawtooth structure with 3d 7 Co 2+ ions

While certain magnetic sublattices have long been known theoretically to give rise to emergent physics via competing magnetic interactions and quantum effects, finding such configurations in real materials is often deeply challenging. Here we report the synthesis and characterization of a new such material, NaCo 2 (SeO 3 ) 2 (OH) which crystallizes with a highly frustrated sublattice of sawtooth Co 2+ chains. Single crystals of NaCo 2 (SeO 3 ) 2 (OH) were synthesized using a low-temperature hydrothermal method. X-ray single crystal structure analysis reveals that the material crystallizes in orthorhombic space group of Pnma (no. 62). Its crystal structure exhibits one-dimensional chains of corner-sharing isosceles triangles that are made of two crystallographically distinct 3d 7 Co 2+ sites (Co(1) and Co(2)). The chains run along the b-axis and are interconnected via [SeO 3 ] groups to form a three-dimensional structure mediating super-exchange interactions. The temperature dependent magnetization data show a ferromagnetic-like (FM) transition at 11 K (T 1 ) followed by an antiferromagnetic (AFM) transition at about 6 K (T 2 ). Neutron-powder diffraction measurements reveal that at T 1 = 11 K only the Co(2) site orders magnetically, forming ferromagnetic zigzag chains along the b-axis. Below T 2 = 6 K, both Co(1) and Co(2) sites order in a nearly orthogonal configuration, with Co(1) moments lying inside the plane of the sawtooth chain while Co(2) moments cant out of the plane. The canting of the magnetic moments leads to a net ferromagnetic component along b-axis, parallel to the chain direction. The ordered moments are fully compensated in the ac-plane. Inelastic neutron scattering measurements reveal crystal field excitations that are consistent with the presence of a spin–orbital entangled pseudo-spin state J eff = 1/2 for the Co 2+ ions. Low-energy spin-wave excitations are observed below the second magnetic transition. The analysis of powder excitation spectrum suggests complex exchange interactions that go beyond a Heisenberg Hamiltonian model with nearest neighbor couplings. Our results demonstrate the richness of the magnetic properties of sawtooth-type structures and encourage the study of similar structures with different oxyanion groups.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

TRTR NRAD NRS Beamline Abstract

The Neutron Radiography (NRAD) Reactor is a 250kW TRIGA housed under the largest hot cell in the United States, making it the foremost location to perform neutron imaging of irradiated nuclear fuels and materials, including those intended for use with advanced reactors. Currently, NRAD has two radial beamlines that are used for neutron radiography and tomography. Upgrades to the North neutron beamline include the replacement of the in-tank beam chamber, through-the-wall collimator, and neutron shutter. These beamline upgrades will not only improve image quality for current capabilities but will also condition the beam to be more suitable for advanced methods such as neutron powder diffraction. These upgrades will increase the excess reactivity of the core, reduce unnecessary activation and exposure to workers, and significantly reduce the amount of shielding required around the beam. This presentation will describe how these upgrades improve beam quality, increase utilization of the reactor, and reduce radiation exposure to personnel.

21 - SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLAN↗

DOE OSTI2021

Antiferromagnetism and crystalline electric field excitations in tetragonal NaCeO 2

In this work, we investigate the crystal structure, magnetic properties, and crystalline electric field of tetragonal, I 4 1 / a m d , Na Ce O 2 . In this compound, Ce 3 + ions form a tetragonally elongated diamond lattice coupled by antiferromagnetic interactions ( Θ CW = - 7.69 K) that magnetically order below T N = 3.18 K. The Ce 3 + J = 5 / 2 crystalline electric field-split multiplet is studied via inelastic neutron scattering to parametrize a J eff = 1 / 2 ground state doublet composed of states possessing mixed | m z ) character. Neutron powder diffraction data reveal the onset of A -type antiferromagnetism with μ = 0.57 ( 2 ) μ B moments aligned along the c axis. The magnetic structure is consistent with the expectations of a frustrated Heisenberg J 1 - J 2 model on the elongated diamond lattice with effective exchange values J 1 > 4 J 2 and J 1 > 0 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2020

Magnetic field induced phase transition in spinel GeNi 2 O 4

Cubic spinel GeNi 2 O 4 exhibits intriguing magnetic properties with two successive antiferromagnetic phase transitions (T N1 ≈ 12.1 and T N2 ≈ 11.4 K) with the absence of any structural transition. We have performed detailed heat capacity and magnetic measurements in different crystallographic orientations. A new magnetic phase in presence of magnetic field (H ≥ 4 T) along the [111] direction is revealed, which is not observed when the magnetic field is applied along the [100] and [110] directions. High field neutron powder diffraction measurements confirm such a change in magnetic phase, which could be ascribed to a spin reorientation in the presence of magnetic field. In conclusion, a strong magnetic anisotropy and competing magnetic interactions play a crucial role on the complex magnetic behavior in this cubic system.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2025

Pressure-induced tuning of the triangular-honeycomb structure of ferroelectric quantum spin liquid candidate, TbInO 3

The pressure response of the triangular-honeycomb-structured quantum spin liquid candidate, TbInO 3 , has been determined via neutron powder diffraction up to 5.75(5) GPa. The system retains hexagonal symmetry up to the maximum pressure considered. The structure was found to compress less anisotropically than related compounds, though it is more compressible within the 2D plane than between subsequent layers. Through extracting the O-atom coordinates we find experimental evidence that may suggest the enhancement of ferroelectricity at pressures as low as 3 GPa.

Ridley, Christopher J. [Oak Ridge National Laborat↗

DOE OSTI2024

Magnon gap tuning in lithium-doped MnTe

Manganese telluride (MnTe) is a prospective platform for ultrafast carrier dynamics, spin-based thermoelectrics, and magnon-drag transport due to its unique electronic and magnetic properties. We use inelastic neutron scattering to study both pure and lithium-doped MnTe, focusing on the influence of doping in opening a magnon gap. We use neutron powder diffraction to determine critical exponents for the phase transition in both pure and Li-doped MnTe and complement this information with muon spin rotation/relaxation. In conclusion, the opening of the magnon gap and spin reorientation in Li-doped MnTe is mainly due to increased magnetic anisotropy along the [001] axis, a feature not present in pure MnTe.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2018

Signatures of the unique microstructure of additively manufactured steel observed via diffraction

A series of measurements were designed to gain confidence in the interpretation of the peak breadth in diffraction patterns collected from additively manufactured material, which has a novel microstructure in comparison to the well understood microstructure of wrought materials. Stainless steels made with two additive manufacturing techniques were compared to wrought material. Similar patterns observed in the scattering vector dependence for additively manufactured and deformed wrought materials suggested that the broadening in both materials was related to dislocations. Finally, this was confirmed by heat-treatment, during which both materials exhibited recovery due to the annealing of dislocations at the same temperature.

304L stainless-steel↗

DOE OSTI2025

Short-range magnetic order and planar anisotropy in the topological ferrimagnet Mn 3 ⁢Si 2 ⁢Te 6

Mn 3 ⁢Si 2 ⁢Te 6 is a ferrimagnetic topological nodal-line semiconductor that exhibits unconventional colossal magnetoresistance behavior, with short-range spin fluctuations being potentially intimately linked to the emergent properties. Here we determine the short-range magnetic order and anisotropy through total neutron scattering and polarized neutron powder diffraction measurements on polycrystalline Mn 3 ⁢Si 2⁢ Te 6 . Strong in-plane anisotropy is quantified on the Mn ions through extraction of the local site susceptibility tensor. Here, the real-space local spin structure is determined through the application of magnetic pair distribution function analysis covering a wide temperature range. Short-range order over a locally frustrated trimer of three nearest neighbors is found to exist well above the long-range ferrimagnetic transition.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Materials for learning use of GSAS-II

The General Structure Analysis System (GSAS-II) package provides materials and crystallographic analysis for all types of diffraction data. It was initially made available with very limited capabilities, but over much of the last decade the features have been expanded, so that GSAS-II is now a comprehensive tool for nearly all types of structural and materials characterization studies. The need to provide materials to teach use of GSAS-II, while the software has been undergoing constant revision and expansion, has required new approaches for documentation. This has included providing tutorials, as each major new capability has been added, and context-sensitive help for each section of the program. Comments in the code are also expanded into a software reference guide. Finally, most recently, video versions of more than half of the tutorials were created and others were provided with animated graphics. All GSAS-II documentation is web-based.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2024

Magnetic structure and magnetoelectric coupling in the antiferromagnet Co 5⁢ (Te⁢O 3 ) 4 ⁢Cl 2

The van der Waals (vdW) layered multiferroics, which host simultaneous ferroelectric and magnetic orders, have attracted attention not only for their potentials to be utilized in nanoelectric devices and spintronics, but also offer alternative opportunities for emergent physical phenomena. To date, the vdW layered multiferroic materials are still very rare. In this work, we have investigated the magnetic structure and magnetoelectric (ME) effects in Co 5 ⁢(Te⁢O 3 ) 4 ⁢Cl 2 , a promising multiferroic compound with antiferromagnetic (AFM) Néel point T N ~18 K. The neutron-powder diffraction reveals the noncoplanar AFM state with preferred Néel vector along the c axis, while a spin reorientation occurring between 8 and 15 K is identified, which results from the distinct temperature dependence of the nonequivalent Co site's moment in Co 5 ⁢(Te⁢O 3 ) 4 ⁢Cl 2 . Moreover, it is found that Co 5 ⁢(Te⁢O 3 ) 4 ⁢Cl 2 is one of the best vdW multiferroics studied so far in terms of the multiferroic performance. The measured linear ME coefficient exhibits the emergent oscillation dependence of the angle between magnetic field and electric field, and the maximal value is as big as 45 ps/m. Finally, it is suggested that Co 5 ⁢(Te⁢O 3 ) 4 ⁢Cl 2 is an appreciated platform for exploring the emergent multiferroicity in vdW layered compounds.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2025

Observation of Orbital-Selective Dual Modulations in an Anisotropic Antiferromagnetic Kagome Metal TbTi 3 ⁢Bi 4

Orbital selectivity is pivotal in dictating the phase diagrams of multiorbital systems, with prominent examples including the orbital-selective Mott phase and superconductivity. The intercalation of anisotropic layers represents an effective method for enhancing orbital selectivity and thereby shaping the low-energy physics of multiorbital systems. Despite its potential, related experimental studies, especially those elucidating the correlation between orbital selectivity and magnetism, remain limited. In this work, we systematically examine the interplay between orbital selectivity and magnetism in the newly discovered anisotropic kagome TbTi 3 ⁢Bi 4 single crystal, and report the coexistence of orbital-selective dual-band modulations (𝑞 1 ∼ 1/3⁢𝑎*, 𝑞 2 ∼ 0.28⁢𝑏*) within the antiferromagnetic (AFM) state. By combining soft x-ray and vacuum ultraviolet angle-resolved photoemission spectroscopy measurements, neutron powder diffraction, scanning tunneling microscopy, and density-functional-theory calculations, we identify these dual-band reconstructions as manifestations of the AFM order driven by a (approximately 1/3, 0.28, 0) nesting instability of the intercalated Tb 5⁢𝑑 𝑥⁢𝑧 orbitals. These orbital-selective modulations induce unusual momentum-dependent band folding and lead to the emergence of Dirac cones only at the $\bar{M}$ 1 point, signaling a topological phase transition in the AFM state. Importantly, the discovery of orbital-selective (approximately 1/3, 0.28, 0) AFM order offers crucial insights into the mechanism underlying the fractional magnetization plateau in this kagome AFM metal. Our findings not only underscore the essential role of both conducting and localized electrons in determining the magnetic orders of Ln⁢Ti 3 ⁢Bi 4 (Ln = lanthanide) kagome metals but also offer a pathway for manipulating magnetism through selective control of anisotropic electronic structures.

Zhang, Renjie [Shanghai Jiao Tong University (Chin↗