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1. Is Ba ₃ In ₂ O ₆ a high-T _c superconductor?

   https://doi.org/10.1088/1361-648X/ad42f3  

   Hensling, F. V. E.; Dahliah, D.; Smeaton, M. A.; Shrestha, B.; Show, V.; Parzyck, C. T.; Hennighausen, C.; Kotsonis, G. N.; Rignanese, G-M; Barone, M. R.; et al (May 2024, Journal of Physics: Condensed Matter)

   Abstract It has been suggested that Ba₃In₂O₆might be a high-T_csuperconductor. Experimental investigation of the properties of Ba₃In₂O₆was long inhibited by its instability in air. Recently epitaxial Ba₃In₂O₆with a protective capping layer was demonstrated, which finally allows its electronic characterization. The optical bandgap of Ba₃In₂O₆is determined to be 2.99 eV in-the (001) plane and 2.83 eV along thec-axis direction by spectroscopic ellipsometry. First-principles calculations were carried out, yielding a result in good agreement with the experimental value. Various dopants were explored to induce (super-)conductivity in this otherwise insulating material. NeitherA- norB-site doping proved successful. The underlying reason is predominately the formation of oxygen interstitials as revealed by scanning transmission electron microscopy and first-principles calculations. Additional efforts to induce superconductivity were investigated, including surface alkali doping, optical pumping, and hydrogen reduction. To probe liquid-ion gating, Ba₃In₂O₆was successfully grown epitaxially on an epitaxial SrRuO₃bottom electrode. So far none of these efforts induced superconductivity in Ba₃In₂O_6,leaving the answer to the initial question of whether Ba₃In₂O₆is a high-T_csuperconductor to be ‘no’ thus far. 

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2. Characterization of a Nitrogenase Iron Protein Substituted with a Synthetic [Fe ₄ Se ₄ ] Cluster

   https://doi.org/10.1002/anie.202202271  

   Solomon, Joseph B.; Tanifuji, Kazuki; Lee, Chi Chung; Jasniewski, Andrew J.; Hedman, Britt; Hodgson, Keith O.; Hu, Yilin; Ribbe, Markus W. (March 2022, Angewandte Chemie International Edition)

   Abstract The Fe protein of nitrogenase plays multiple roles in substrate reduction and cluster maturation via its redox‐active [Fe₄S₄] cluster. Here we report the synthesis and characterization of a water‐soluble [Fe₄Se₄] cluster that is used to substitute the [Fe₄S₄] cluster of theAzotobacter vinelandiiFe protein (AvNifH). Biochemical, EPR and XAS/EXAFS analyses demonstrate the ability of the [Fe₄Se₄] cluster to adopt the super‐reduced, all‐ferrous state upon its incorporation intoAvNifH. Moreover, these studies reveal that the [Fe₄Se₄] cluster inAvNifH already assumes a partial all‐ferrous state ([Fe₄Se₄]⁰) in the presence of dithionite, where its [Fe₄S₄] counterpart inAvNifH exists solely in the reduced state ([Fe₄S₄]¹⁺). Such a discrepancy in the redox properties of theAvNifH‐associated [Fe₄Se₄] and [Fe₄S₄] clusters can be used to distinguish the differential redox requirements for the substrate reduction and cluster maturation of nitrogenase, pointing to the utility of chalcogen‐substituted FeS clusters in future mechanistic studies of nitrogenase catalysis and assembly. 

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3. Structure Effect on Pseudocapacitive Properties of A ₂ LaMn ₂ O ₇ (A = Ca, Sr)

   https://doi.org/10.1002/ente.202201249  

   Kananke-Gamage, Chandana C. W.; Ramezanipour, Farshid (January 2023, Energy Technology)

   Herein, the effect of structure on pseudocapacitive properties in alkaline conditions is demonstrated through the investigation of isoelectronic oxides Ca₂LaMn₂O₇and Sr₂LaMn₂O₇, where the difference in ionic radii of Ca²⁺and Sr²⁺leads to a change in structure and lattice symmetry, resulting in an orthorhombicCmcmstructure for the former and a tetragonalI4/mmmstructure for the latter. While calcium and strontium do not make a direct contribution to the near‐surface faradaic processes that are essential to the pseudocapacitive properties, their effect on the structure leads to a change in the oxygen intercalation process and the associated pseudocapacitive energy storage. It is shown that Sr₂LaMn₂O₇has a significantly greater specific capacitance than Ca₂LaMn₂O₇. In addition, the former shows a considerably higher‐energy density compared to the latter. Furthermore, these materials show highly stable energy‐storage properties, and retain their specific capacitance over 10 000 cycles of charge–discharge in a symmetric pseudocapacitive cell. Importantly, these findings show the structure–property relationships, where a change in the structure and lattice symmetry can result in a significant change in pseudocapacitive charge–discharge properties in isoelectronic systems. 

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4. Impact of impurities on the thermal properties of a Li ₂ S–SiS ₂ –LiPO ₃ glass

   https://doi.org/10.1111/ijag.16654  

   Wheaton, Jacob; Martin, Steve W (July 2024, International Journal of Applied Glass Science)

   Abstract The preparation of 0.58 Li₂S + 0.315 SiS₂+ 0.105 LiPO₃glass, and the impacts of polysulfide and P^1Pdefect structure impurities on the glass transition temperature (T_g), crystallization temperature (T_c), working range (ΔT≡ T_c‐ T_g), fragility index, and the Raman spectra were evaluated using statistical analysis. In this study, 33 samples of this glass composition were synthesized through melt‐quenching. Thermal analysis was conducted to determine the glass transition temperature, crystallization temperature, working range, and fragility index through differential scanning calorimetry. The quantity of the impurities described above was determined through Raman spectroscopy peak analysis. Elemental sulfur was doped into a glass to quantify the wt% sulfur content in the glasses. Linear regression analysis was conducted to determine the impact of polysulfide impurities and P^1Pdefect impurities on the thermal properties. Polysulfide impurities were found to decrease theT_gat rate of nearly 12°C per 1 wt% increase in sulfur concentration. The sulfur concentration does not have a statistically significant impact on the other properties (α = 0.05). The P^1Pdefect structure appears to decrease the resistance to crystallization of the glass by measurably decreasing the working range of the glasses, but further study is necessary to fully quantify and determine this. 

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5. Synthesis, Crystal and Electronic Structure of Ca ₄ CdIn ₂ Ge ₄ : A Quaternary Variant of the Monoclinic Mg ₅ Si ₆ Structure

   https://doi.org/10.1002/zaac.202500006  

   Ghosh, Kowsik; Bobev, Svilen (May 2025, Zeitschrift für anorganische und allgemeine Chemie)

   Reported is the synthesis of a new polar intermetallic phase, Ca₄CdIn₂Ge₄, crystals of which can be readily obtained employing the In‐flux method. The structure and the chemical composition of the new compound are established based on single‐crystal X‐Ray diffraction and energy‐dispersive X‐Ray spectroscopy data. Ca₄CdIn₂Ge₄crystallizes in a monoclinic crystal system with the space groupC2/m(no. 12) with lattice parametersa = 16.7383(12) Å,b = 4.4235(3) Å,c = 7.4322(5) Å, andβ = 106.560(1)°. The structure can formally be classified as a variant of the Mg₅Si₆structure type (Pearson symbolmS22). Considering the InGe and CdGe interactions as mostly covalent, the polyanionic substructure can be rationalized as consisting of ribbons of edge‐shared [InGe₄] tetrahedra connected by Ge₂dimers and bridged by Cd atoms in nearly square‐planar environment. Chemical bonding analysis based on TB‐LMTO‐ASA calculations affirms the notion for covalent character of the GeGe bonding with the dimers. The calculations also show that the bonding in the tetrahedra is more covalent in character than the bonding in square‐planar fragments, with the CaGe interactions being the least covalent among all interactions, though not exactly ionic. 

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