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1. Specimen-displacement correction for powder X-ray diffraction in Debye–Scherrer geometry with a flat area detector. Erratum

   Benjamin S. Hulbert and Waltraud M. Kriven (March 2023, Journal of applied crystallography)

   Edited by H. Brand, Australian Synchrotron (Ed.)

   In the article by Hulbert & Kriven (2023), there is an error in Fig. 2(b) which shows the Bragg–Brentano geometry for an X-ray diffraction (XRD) experiment. The arc denoting the angle 2θ + δ was mistakenly drawn so that it ended at the base of the specimen. However, it should extend to the incident beam. The revised Fig. 2(b) diagram is given here, shown in Fig. 1. Both the derived equation and the conclusions in the original article are unaffected by this figure correction. 

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2. High-speed X-ray imaging of droplet-powder interaction in binder jet additive manufacturing

   https://doi.org/10.1016/j.addma.2024.104269  

   Lawrence, Jacob E; Lawrence, Madi P; Fezzaa, Kamel; Clark, Samuel J; Crane, Nathan B (June 2024, Additive Manufacturing)

   Binder jetting (BJ) is an additive manufacturing process that uses a powder feedstock in a layer wise process to print parts by selectively depositing a liquid binder into the powder bed using inkjet technology. This study presents findings from high-speed synchrotron imaging of binder droplet-interaction during the BJ printing process. A custom laboratory-scale BJ test platform was used for testing which enabled control of relevant process parameters including powder material, print geometry, spacing between droplets, powder bed density, and powder moisture content. Powder ejection was observed above the powder bed surface and powder relocation due to droplet impact was observed below the powder bed surface. Powder relocation was observed to be sensitive to powder material, powder bed density, powder bed moisture, droplet spacing, and print geometry. Increasing powder bed density was found to increase particle ejection velocity but reduce the total number of particles ejected. Process parameters that increase binder / moisture content in the powder bed were found to reduce powder ejection. The number of ejected powder particles was reduced for lower droplet spacings. Both powder ejection and powder relocation below the powder bed were reduced by treating the surface of the powder bed with a water/triethylene glycol (TEG) mixture before printing. Results from this study help to build understanding of the physical mechanisms in the BJ printing process that may contribute to formation of defects observed in final parts. 

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3. Lithium nickel borides: evolution of [NiB] layers driven by Li pressure

   https://doi.org/10.1039/D0QI01150A  

   Gvozdetskyi, Volodymyr; Sun, Yang; Zhao, Xin; Bhaskar, Gourab; Carnahan, Scott L.; Harmer, Colin P.; Zhang, Feng; Ribeiro, Raquel A.; Canfield, Paul C.; Rossini, Aaron J.; et al (January 2021, Inorganic Chemistry Frontiers)

   null (Ed.)

   Here we show the effect of Li chemical pressure on the structure of layered polymorphs with LiNiB composition: RT -LiNiB (room temperature polymorph) and HT -LiNiB (high temperature polymorph), resulting in stabilization of the novel RT -Li 1+x NiB ( x ∼ 0.17) and HT -Li 1+y NiB ( y ∼ 0.06) phases. Depending on the synthesis temperature and initial Li content, precisely controlled via hydride route synthesis, [NiB] layers undergo structural deformations, allowing for extra Li atoms to be accommodated between the layers. In situ variable temperature synchrotron and time-dependent laboratory powder X-ray diffraction studies suggest Li step-wise deintercalation processes: RT- Li 1+x NiB → RT- LiNiB (high temp.) → LiNi 3 B 1.8 → binary Ni borides and HT -Li 1+y NiB → HT -LiNiB (high temp.) → LiNi 3 B 1.8 → binary Ni borides. Quantum chemistry calculations and solid state 7 Li and 11 B NMR spectroscopy shed light on the complexity of real superstructures of these compounds determined from high resolution synchrotron powder diffraction data. 

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4. Isotropic negative thermal expansion in ZrW2O8 and HfW2O8 from 1100 to 1275◦C

   Benjamin S. Hulbert, Dylan W. (January 2024, Journal of the American Ceramic Society)

   Tatsuki Ohji, Ph. D. Editor (Ed.)

   ZrW2O8 (ZrO2•2WO3) and HfW2O8 (HfO2•2WO3) have been the focus of thermal expansion studies due to their isotropic negative thermal expansion (NTE) measured previously at temperatures below 775◦C. This work presents measurements of these materials at their thermodynamically stable temperature ranges of 1105 and 1257◦C for ZrW2O8 and 1105–1276◦C for HfW2O8, where they were characterized with in situ, powder X-ray diffraction. The linear coefficients of thermal expansion were measured to be −5.52 × 10−6 and −4.87 × 10−6◦C−1 for ZrW2O8 and HfW2O8, respectively. The mechanism leading to this NTE is discussed. Powder samples were synthesized by a solution-based process called the organic–inorganic steric entrapment method. In situ characterization in air was carried out at the National Synchrotron Light Source II using a hexapole lamp, optical furnace and theAdvanced Photon Source using a quadrupole lamp, optical furnace to achieve elevated temperatures. 

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5. Crystal structure and synchrotron X-ray powder reference pattern for the porous pillared cyanonickelate, Ni(3-amino-4,4′-bipyridine)[Ni(CN) ₄ ]

   https://doi.org/10.1017/S0885715624000058  

   Wong-Ng, W; Culp, J; Kaduk, JA; Chen, YS; Lapidus, S (March 2024, Powder Diffraction)

   The structure of Ni(3-amino-4,4′-bipyridine)[Ni(CN)₄] (or known as Ni-BpyNH₂) in powder form was determined using synchrotron X-ray diffraction and refined using the Rietveld refinement technique (R= 8.8%). The orthorhombic (Cmca) cell parameters were determined to bea= 14.7218(3) Å,b= 22.6615(3) Å,c= 12.3833(3) Å,V= 4131.29(9) ų, andZ= 8. Ni-BpyNH₂forms a 3-D network, with a 2-D Ni(CN)₄net connecting to each other via the BpyNH₂ligands. There are two independent Ni sites on the net. The 2-D nets are connected to each other via the bonding of the pyridine “N” atom to Ni2. The Ni2 site is of six-fold coordination to N with relatively long Ni2–N distances (average of 2.118 Å) as compared to the four-fold coordinated Ni1–C distances (average of 1.850 Å). The Ni(CN)₄net is arranged in a wave-like fashion. The functional group, –NH₂, is disordered and was found to be in them-position relative to the N atom of the pyridine ring. Instead of having a unique position, N has ¼ site occupancy in each of the fourm-positions. The powder reference diffraction pattern for Ni-BpyNH₂was prepared and submitted to the Powder Diffraction File (PDF) at the International Centre of Diffraction Data (ICDD). 

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