Solid solution dependence of the deformation behavior in Mg–xZn (x = 0, 1, 2 wt%) alloys: In-situ neutron diffraction and crystal plasticity modeling
Not Available
Wang, Huai (ORCID:0000000206168248)↗
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Synthesis and Crystal and Electronic Structures of the Zintl Phase Sr21Cd4Sb18
Reported herein are the synthesis and crystal chemistry analysis of the Zintl phase Sr21Cd4Sb18. Single crystals of this compound were grown using the Sn-flux method, and structural characterization was carried out using single-crystal X-ray diffraction. Crystal data: Monoclinic space group C2/m (No. 12, Z = 4); a = 18.2536(6) Å, b = 17.4018(5) Å, and c = 17.8979(6) Å, β = 92.024(1)°. The structure is based on edge- and corner-shared CdSb4 tetrahedra, which ultimately form octameric [Cd8Sb22] fragments, where two symmetry-equivalent subunits are connected via a homoatomic Sb–Sb interaction. The electronic band structure calculations contained herein reveal the emergence of a direct gap between the valence and the conduction bands.
Ghosh, Kowsik (ORCID:0000000326227046)↗
The crystal structure of strontium bromide monohydrate.
Crystal structure of strontium bromide monohydrate by X-ray single crystal diffraction techniques
STRONTIUM BROMIDE↗
Modeling and experimental validation of dynamical effects in Bragg coherent x-ray diffractive imaging of finite crystals
Bragg coherent diffractive imaging (BCDI) is a noninvasive microscopy technique that can visualize the shape and internal lattice deviations of crystals with nanoscale spatial resolution and picometer deformation sensitivity. Its strain imaging capability relies on Fourier transform–based iterative phase retrieval algorithms, which are mostly developed under the kinematical approximation. Such approximation prohibits the application of BCDI on larger crystals, which are commonly seen in most emerging functional materials. Understanding the dynamical effect in BCDI, as well as developing a validated method for modeling BCDI at the dynamical diffraction limit, is crucial for applying BCDI to hierarchical systems that contain micron-sized crystals and grains. Thus we report a comparative study on the impact of dynamical diffraction effects by comparing the reconstruction results from two measurements of the same crystal. Forward simulation is implemented to show subtle changes of interference fringes in the diffraction pattern due to the dynamical diffraction, and is compared directly with the experimental data.
36 MATERIALS SCIENCE↗
Altermagnetism in the layered intercalated transition metal dichalcogenide CoNb 4 Se 8
Altermagnets (AMs) are a new class of magnetic materials that combine the beneficial spintronics properties of ferromagnets and antiferromagnets, garnering significant attention recently. Here, we have identified altermagnetism in a layered intercalated transition metal diselenide, CoNb 4 Se 8 , which crystallizes with an ordered sublattice of intercalated Co atoms between NbSe 2 layers. Single crystals are synthesized, and the structural characterizations are performed using single crystal diffraction and scanning tunneling microscopy. Magnetic measurements reveal easy-axis antiferromagnetism below 168 K. Density functional theory (DFT) calculations indicate that A-type antiferromagnetic ordering with easy-axis spin direction is the ground state, which is verified through single crystal neutron diffraction experiments. Electronic band structure calculations in this magnetic state display spin-split bands, confirming altermagnetism in this compound. The layered structure of CoNb 4 Se 8 presents a promising platform for testing various predicted properties associated with altermagnetism.
36 MATERIALS SCIENCE↗
Increasing the bulk of the 1TEL–target linker and retaining the 10×His tag in a 1TEL–CMG2-vWa construct improves crystal order and diffraction limits
TELSAM-fusion crystallization has the potential to become a revolutionary tool for the facile crystallization of proteins. TELSAM fusion can increase the crystallization rate and enable crystallization at low protein concentrations, in some cases with minimal crystal contacts [Nawarathnage et al. (2022), Open Biol. 12 , 210271]. Here, requirements for the linker composition between 1TEL and a fused CMG2 vWa domain were investigated. Ala-Ala, Ala-Val, Thr-Val and Thr-Thr linkers were evaluated, comparing metrics for crystallization propensity and crystal order. The effect on crystallization of removing or retaining the purification tag was then tested. It was discovered that increasing the linker bulk and retaining the 10×His purification tag improved the diffraction resolution, likely by decreasing the number of possible vWa-domain orientations in the crystal. Additionally, it was discovered that some vWa-domain binding modes are correlated with scrambling of the 1TEL polymer orientation in crystals and an effective mitigation strategy for this pathology is presented.
1TEL↗
A scalable transformer model for real-time decision making in neutron scattering experiments
The U.S. Department of Energy's (DOE's) neutron research facilities at Oak Ridge National Laboratory (ORNL), including the High Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS), are a state-of-the-art neutron scattering facility that allows researchers to study the structure and dynamics of materials at the atomic scale. At the SNS, neutrons are measured using the time-of-flight (TOF) technique as they move through a neutron beamline to interact with a sample. Large volumes of neutron scattering data are collected and recorded in neutron event mode. Optimal productivity of the TOF instrument is limited due to the lack of real-time data analysis tools. The large amount of data generated by the experiments can be challenging to process and analyze in real time, particularly for experiments that require rapid feedback and adjustment of experimental parameters. The regular computer/workstation cannot keep up with the experiment speed to provide real-time feedback to adjust experimental parameters, so connecting the supercomputers available to the neutron facility is necessary to achieve real-time data analysis and experiment steering. To address this challenge, we exploit the Frontier supercomputer at Oak Ridge Leadership Computing Facility (OLCF) to train a scalable temporal fusion transformer model for real-time decision making of TOF neutron scattering experimentation. Here, in this paper, we present the results using Frontier to provide the processing power needed to rapidly process and analyze large volumes of single-crystal diffraction data collected at TOPAZ, a neutron time-of-flight Laue single-crystal diffractometer at the SNS.
97 MATHEMATICS AND COMPUTING↗
High-Resolution In-Situ Synchrotron X-Ray Studies of Inorganic Perovskite CsPbBr[subscript 3]: New S
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Liu, Sizhan↗
On single-crystal neutron-diffraction in DACs: quantitative structure refinement of light elements on SNAP and TOPAZ
Quantitative single crystal neutron-diffraction in diamond anvil cells has so far been limited by the neutron flux available at the various neutron sources. As a result, highly precise measurements of the exact position of light elements have not been possible preventing, for example, structural studies of hydrogen and hydrogen bonds under pressure. Here we report experiments carried out on SNAP at the Spallation Neutron Source (ORNL, TN, USA) to explore the possibility and current limits of such studies. Furthermore, we benchmarked the obtained data quality with reference experiments carried out on TOPAZ, a dedicated single-crystal instrument.We show that measuring single-crystal diffraction intensities on SNAP is possible to such a precision that we are able to resolve the hydrogen bonds in potassium dideuterium phosphate (DKDP) as well as in ice VI.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Electron Diffraction of 3D Molecular Crystals
Not Available
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Crystals of $\mathrm{TELSAM}$–target protein fusions that exhibit minimal crystal contacts and lack direct inter-$\mathrm{TELSAM}$ contacts
While conducting pilot studies into the usefulness of fusion to TELSAM polymers as a potential protein crystallization strategy, we observed novel properties in crystals of two TELSAM–target protein fusions, as follows. (i) A TELSAM–target protein fusion can crystallize more rapidly and with greater propensity than the same target protein alone. (ii) TELSAM–target protein fusions can be crystallized at low protein concentrations. This unprecedented observation suggests a route to crystallize proteins that can only be produced in microgram amounts. (iii) The TELSAM polymers themselves need not directly contact one another in the crystal lattice in order to form well-diffracting crystals. This novel observation is important because it suggests that TELSAM may be able to crystallize target proteins too large to allow direct inter-polymer contacts. (iv) Flexible TELSAM–target protein linkers can allow target proteins to find productive binding modes against the TELSAM polymer. (v) TELSAM polymers can adjust their helical rise to allow fused target proteins to make productive crystal contacts. (vi). Fusion to TELSAM polymers can stabilize weak inter-target protein crystal contacts. We report features of these TELSAM–target protein crystal structures and outline future work needed to validate TELSAM as a crystallization chaperone and determine best practices for its use.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A phase-stepped point diffraction interferometer using liquid crystals
A new instrument, the liquid crystal point diffraction interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with high data density and with automated data reduction. The design of the LCPDI is briefly discussed. An algorithm is presented for eliminating phase measurement error caused by object beam intensity variation from frame-to-frame. The LCPDI is demonstrated by measuring the temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to independently measured results and show excellent agreement with them. It is expected that this instrument will have application in the fluid sciences as a diagnostic tool, particularly in space based applications where autonomy, robustness, and compactness are desirable qualities. It should also be useful for the testing of optical elements, provided a master is available for comparison.
Mercer, Carolyn R.↗
DIFFRACTION GRADE SINGLE-CRYSTAL DIAMONDS WITH THE EXCEPTIONALLY LOW DENSITY OF DEFECTS
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36 MATERIALS SCIENCE↗
Variable Bragg x-ray beam splitters
Beam splitters are utilized in a variety of advanced x-ray instruments and are essential for extending quantum optics techniques to x rays. A new fabrication method has produced thinned Bragg diffracting silicon devices with variable reflectivity and transmission coefficients and negligible absorption losses. Diffraction measurements confirm that silicon continues to exhibit perfect crystal diffraction even for thicknesses below two microns. Devices are machined from standard wafers, with the thinned regions contained within the robust frame of an unperturbed crystal for ease of handling.
Powers, L. T. (ORCID:000900047481248X)↗
The crystal structure of a new calcium aluminate phase containing formate
A new calcium aluminate phase containing formate ions was synthesized and its crystal structure determined. This new phase is indicated as M-phase and was firstly observed in Portland cement pastes hydrated in presence of Ca-formate and in excess of water. The crystal structure of the M-phase was successfully solved in the R-3 space group of the trigonal system on the basis of synchrotron X-ray single crystal diffraction data. The structural model was confirmed by Rietveld refinement of the powder diffraction data acquired on the synthesized pure sample. The crystal structure of the M-phase is similar to that of ettringite, being characterized by columns of AlO{sub 6} octahedra alternating with groups of three edge-sharing CaO{sub 7} polyhedra. The formate ions (HCOO){sup −} share two oxygens with Ca polyhedra and are located in the interspace between the columns. The crystal structure of the M-phase testifies the strong interaction occurring between small organic molecules as formate and the calcium aluminate components of Portland cement.
36 MATERIALS SCIENCE↗
Large Diffraction-Grade Single Crystal Diamond for Applications at New Generation Synchrotron and FEL X-Ray Sources
As a result of increasing performance of synchrotron and free-electron laser x-ray sources for high-flux applications, a new generation of optics is needed that can support the high energy densities utilized. To achieve this, the Department of Energy (DOW) has sought a commercially available, US-sourced supply of this material. Through a collaborative effort led by WD Advanced Materials (WD AM), in coordination with Euclid Beamlabs and Applied Diamond, Inc., and supported by Argonne National Laboratory, an effort has been made to begin the creation of such a diamond optic supply. Key material and optic parameters were identified, as well as characterization methods. A process of diamond synthesis that satisfies both extrinsic and intrinsic needs of the optics was formulated and demonstrated, and necessary steps to achieve high-quality epitaxy were evaluated and tested. Results of the first steps of this program are provided herein, as well as recommendations for a follow-up effort to complete the program and establish the needed supply of diamond optics for DOE x-ray applications.
36 MATERIALS SCIENCE↗
High-resolution bandpass x-ray imaging with crystal reflectors: Overcoming geometric aberrations
The imaging problem of a specular reflector is revisited. Retaining terms through the second order in the reflector surface expansion, we derive the form of the aberration-limiting aperture for arbitrary magnification, assuming no bandwidth limitations. A permissible relative aperture size of the reflector is limited by a set relative aberration tolerance and scales with the tangent of the central glancing angle of incidence. These limiting aberrations become practically insignificant near backscattering. The results extend to x-ray diffracting crystals in symmetric Bragg geometry shaped as an ellipsoid of revolution. This geometry permits polychromatic imaging for hard x-rays over a bandwidth defined by the accepted range of Bragg angles, thereby suppressing aberrations of higher orders. We assess ellipsoidal crystal imagers using ray tracing simulations for two high-magnification designs with Bragg angles far from and close to backscattering. Finally, in both cases, the ellipsoidal crystals produce images of higher quality compared to those formed by equivalent toroidal crystal imagers.
Bragg reflection↗
Pyrochlore NaYbO2: A Potential Quantum Spin Liquid Candidate
The search for quantum spin liquids (QSL) and chemical doping in such materials to explore superconductivity have continuously attracted intense interest. Here, we report the discovery of a potential QSL candidate, pyrochlore-lattice β-NaYbO2. Colorless and transparent NaYbO2 single crystals, layered α-NaYbO2 (∼250 μm on edge) and octahedral β-NaYbO2 (∼50 μm on edge), were grown for the first time. Synchrotron X-ray single-crystal diffraction unambiguously determined that the newfound β-NaYbO2 belongs to the three-dimensional pyrochlore structure characterized by the R3̅m space group, corroborated by synchrotron X-ray and neutron powder diffraction and pair distribution function. Magnetic measurements revealed no long-range magnetic order or spin glass behavior down to 0.4 K with a low boundary spin frustration factor of 17.5, suggesting a potential QSL ground state. Under high magnetic fields, the potential QSL state was broken and spins order. Our findings reveal that NaYbO2 is a fertile playground for studying novel quantum states.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗