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Fast Sodium Ion Conductivity in Pristine NaSnP : Synthesis, Structure and Properties of the Two Polymorphs LT‐NaSnP and HT‐NaSnP
No full textAchieving high ionic conductivities in solid state electrolytes is crucial for the development of efficient all-solid-state-batteries. Considering future availability and sustainability, sodium materials hold promises for an alternative for lithium materials in all-solid-state batteries, due to the higher abundance. Here, we report on a sodium phosphide ion conductor Na8SnP4 with a conductivity of 0.53 mS cm−1 at room temperature as a pristine material. Due to the simple tetrahedral SnP4 structure units, Na8SnP4 has potential for optimization through aliovalent substitution as successfully applied in sulfide-based materials. Na8SnP4 is easily accessible from exclusively abundant elements and forms a high- and low-temperature polymorph, which further allows for a fundamental understanding of the structure-property relationship. Both polymorphs are structurally characterized by synchrotron X-ray powder diffraction and MAS–NMR spectroscopy. Ion conductivity and activation energy for ion mobility is determined by temperature dependent impedance spectroscopy and static 23Na-NMR measurements. Both MEM analysis of scattering densities as well as structure determination by Rietveld methods hint for ionic motion between special Na positions in the structure and that ion migration proceeds along pathways passing triangular faces of neighboring tetrahedral and octahedral voids. The specific voids filling in the disordered HT-phase are found to be a crucial parameter for ion migration
Legume protein gelation: The mechanism behind the formation of homogeneous and fractal gels
No full textProtein gelation can provide texture in plant-based foods and can be influenced by many factors, including protein extraction method and salt addition. However, the protein gelation mechanism is still not well understood for plant proteins, especially for isolates obtained using commercial protein extraction processes. Therefore, the structural changes that legume sources such as yellow pea, faba bean, and soybeans undergo during the gelation process to understand the differences in their gelation mechanisms was investigated herein by using small-angle neutron scattering. Among these protein sources, the commercial extraction method was found to play a major part in the gelation pathway. Intensive protein extraction methods involving isoelectric precipitation led to lower protein solubility (∼1–38% w/w), larger insoluble protein particle sizes (60–100 μm), and a gelation pathway that is dependent on the changes of the insoluble protein particles. In contrast, extraction using ultrafiltration instead of precipitation resulted in higher protein solubility (∼18–88% w/w) and smaller insoluble protein particle sizes (40–70 μm), and the structural changes observed during gelation involved the structural changes of both soluble proteins and insoluble proteins. SEM imaging also showed different gel networks, with fractal networks formed by insoluble proteins (for sources with low solubility) or more homogenous networks formed by the interactions between the soluble proteins (for sources with high solubility). Despite the differences observed in the gelation network and the protein solubility, the gelation strength exhibited by protein sources at low protein solubility were similar to the ones by protein sources at high protein solubility, demonstrating the potential of fractal gel networks in providing texture
Deciphering supramolecular and polymer-like behavior in metallogels: real-time insights into temperature-modulated gelation and rapid self-assembly dynamics
No full textBis(pyridyl) urea-based gelators, namely L2 and its isomeric mixture (L1 + L2), are known to self-assemble into 1D architectures capable of inducing supramolecular gelation. Coordination with metal ions such as Ag(I), Cu(II), and Fe(III) introduces structural reinforcement, enabling the formation of distinct 3D networks governed by metal-specific coordination geometries. Here, we present a comprehensive investigation into the temperature-responsive behavior (20–60 °C) of L2 and L1 + L2, both in the absence and presence of Ag(I), Dy(III), Fe(III), Cu(II), and Ho(III), using real-time small-angle neutron scattering (SANS). To probe long-term structural evolution/kinetics of self-assembly, real-time small-angle X-ray scattering (SAXS) was employed on L2 + Ag gels, complemented by differential scanning calorimetry (DSC) to evaluate thermal transitions. Our results reveal strikingly divergent gelation behaviors: L2 forms a highly rigid, covalent polymer-like network, while L1 + L2 exhibits remarkable thermal adaptability. Upon metal coordination, the assemblies exhibit pronounced crystallinity and exceptional thermal stability, as evidenced by persistent Bragg reflections and invariant d-spacings. Intriguingly, L2 : Fe (2 : 1) and L1 : L2 : Fe (0.5 : 0.5 : 1) in acetonitrile-d3 (ACN-d3) deviate from this trend, forming thermally labile amorphous gels. These systems show a complete loss of crystalline order, reduced Porod exponents—indicative of collapsed or branched fiber morphologies—and prominent melting and glass transition events in DSC. Fitting SANS and SAXS data to the correlation length model unveiled insightful nanostructural features. While most systems displayed minimal temperature-induced variation in mesh size or surface morphology, L2 : Ag in dimethyl sulfoxide-d6 (DMSO-d6)/D2O and L2 : Fe (1 : 1) in ACN-d3 exhibited a rare combination of thermally stable correlation lengths and increasing high-q exponents—strongly suggesting progressive fiber densification or surface smoothing within a robust gel framework. These findings highlight the tunability and structural resilience of supramolecular gels through precise control of ligand architecture, metal coordination, and temperature, offering valuable design principles for functional soft materials
Post hot-deformation precipitation behavior of γ′ phase in VDM® alloy 780 under varying cooling rates and aging temperatures: An in situ high energy XRD study
No full textThe performance of polycrystalline Ni-based superalloys is largely determined by the fraction and size of the intermetallic hardening phases, such as the γ′ phase. Understanding the evolution of the γ′ precipitate size and volume fraction during the complex thermomechanical process chain is essential for optimizing the mechanical properties of polycrystalline Ni-based superalloys. In this study, the high temporal resolution of in situ synchrotron X-ray diffraction at elevated temperatures was used to monitor γ′ evolution in VDM® Alloy 780 during cooling and subsequent aging heat treatments in real time. To simulate the industrial forging process, the alloy was initially subjected to compressive deformation at 1000 °C. In the first part of the study, immediately after hot forming, three different cooling rates (10 °C/min, 100 °C/min, and 1000 °C/min) were applied to analyse the in situ evolution of γ′ precipitation. The resulting γ′ phase fraction was highest at the slowest cooling rate, yet even the fastest cooling rate did not completely suppress precipitation. In the second part of the study, the age-hardening response of the alloy was examined at holding temperatures of 720 °C and 800 °C for five hours each. The evolution of the γ′ volume fraction, precipitate size, and lattice parameter was monitored in situ by XRD. After aging, γ′ volume fractions of 15 % and 19 % were obtained, with average precipitate sizes of 9 nm and 18 nm, respectively. The prior deformation enhanced γ′ formation at 720 °C compared to literature data. Complementary Transmission Electron Microscopy (TEM) measurements confirmed precipitate sizes consistent with the diffraction data
Neutron imaging investigation of additively manufactured tungsten nozzles for an arcjet deorbit system
No full textThe Institute of Space Systems is currently developing a deorbit module based on thermal arcjet technology to allow fast orbit decay at end-of-life, with a focus on megaconstellation satellites. By employing additive manufacturing with tungsten, improved nozzle geometries can lead to a gain in overall performance. However, reproducibility is an ongoing concern for additively manufactured parts. Together with the Heinz Maier-Leibnitz Zentrum (MLZ) and the Budapest Neutron Centre of the Centre for Energy Research, a study was conducted scanning additively manufactured arcjet nozzles prior to and after standardized operation via neutron computed tomography. The results show a drop in performance over time, which can be related to changes in the constrictor geometry. Furthermore, cavities created during manufacturing can significantly influence operation
Thermal diffusion behavior of ternary UMoX alloys with Al coating
No full textUranium-molybdenum (UMo) alloys are characterized by 7–10 wt.% Mo content and offer assurance in achieving high densities of U assemblies in fuel compositions, making them a compelling option for research reactors in the quest for high neutron fluxes. However, the use of these materials in fuel plates faces numerous challenges, mostly reflected in the formation of an amorphous interdiffusion layer (IDL) with poor thermal conductivity between the UMo kernel and the Al matrix or cladding. In addition, swelling of the fuel plate and accumulation of gaseous fission products can be observed. These effects can be suppressed by introducing an interdiffusion barrier layer (IDB) between the fuel and the Al matrix/cladding or using ternary alloys (UMoX) instead of binary UMo. This experiment focuses on the second approach, the investigation of ternary UMoX alloys. Zr, Pt, Nb, and Ti are selected as the third candidate element (X) because of their relevant material properties. The experimental work involved the production of UMoX alloys, with a subset of samples undergoing heat treatment at 1173 K for homogenization. All samples were coated with Al using physical vapor deposition (PVD) to mimic the Al matrix and/or cladding in fuel plates. Both the ternary alloys and binary UMo reference samples were annealed to simulate the diffusion processes expected during in-pile operation and to study γ-phase stability. The results revealed that UMoTi and UMoZr are not suitable because of irregular interdiffusion. UMoPt formed a relatively thin and regular IDL compared to that of pure UMo. UMoNb did not show interdiffusion and was chemically stable under long heat treatment. In conclusion, UMoNb and UMoPt are promising candidates for high-density fuels, offering a simpler alternative to UMo fuels, as they do not require an additional IDB layer