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1. 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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2. 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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3. Electronic structure in a transition metal dipnictide TaAs ₂

   https://doi.org/10.1088/1361-648X/ad04fc  

   Regmi, Sabin; Huang, Cheng-Yi; Khan, Mojammel A.; Wang, Baokai; Pradhan Sakhya, Anup; Hosen, M. Mofazzel; Thompson, Jesse; Singh, Bahadur; Denlinger, Jonathan D.; Ishigami, Masahiro; et al (November 2023, Journal of Physics: Condensed Matter)

   Abstract The family of transition-metal dipnictides has been of theoretical and experimental interest because this family hosts topological states and extremely large magnetoresistance (MR). Recently, ${\mathrm{T}\mathrm{a}\mathrm{A}\mathrm{s}}_2$, a member of this family, has been predicted to support a topological crystalline insulating state. Here, by using high-resolution angle-resolved photoemission spectroscopy (ARPES), we reveal both closed and open pockets in the metallic Fermi surface (FS) and linearly dispersive bands on the ( $\bar{2}01$) surface, along with the presence of extreme MR observed from magneto-transport measurements. A comparison of the ARPES results with first-principles computations shows that the linearly dispersive bands on the measured surface of ${\mathrm{T}\mathrm{a}\mathrm{A}\mathrm{s}}_2$are trivial bulk bands. The absence of symmetry-protected surface state on the ( $\bar{2}01$) surface indicates its topologically dark nature. The presence of open FS features suggests that the open-orbit fermiology could contribute to the extremely large MR of ${\mathrm{T}\mathrm{a}\mathrm{A}\mathrm{s}}_2$. 

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4. IrGe ₄ : A Predicted Weyl-Metal with a Chiral Crystal Structure

   https://doi.org/10.1021/acs.inorgchem.3c01528  

   Skaggs, Callista M; Ryu, Dong-Choon; Bhandari, Hari; Xin, Yan; Kang, Chang-Jong; Lapidus, Saul H; Siegfried, Peter E; Ghimire, Nirmal J; Tan, Xiaoyan (December 2023, Inorganic Chemistry)

   Polycrystalline IrGe4 was synthesized by annealing elements at 800 °C for 240 h, and the composition was confirmed by energy-dispersive X-ray spectroscopy. IrGe4 adopts a chiral crystal structure (space group P3121) instead of a polar crystal structure (P31), which was corroborated by the convergent-beam electron diffraction and Rietveld refinements using synchrotron powder X-ray diffraction data. The crystal structure features layers of IrGe8 polyhedra along the b axis, and the layers are connected by edge- and corner-sharing. Each layer consists of corner-shared [Ir3Ge20] trimers, which are formed by three IrGe8 polyhedra connected by edge-sharing. Temperature-dependent resistivity indicates metallic behavior. The magnetoresistance increases with increasing applied magnetic field, and the nonsaturating magnetoresistance reaches 11.5% at 9 T and 10 K. The Hall resistivity suggests that holes are the majority carrier type, with a carrier concentration of 4.02 × 1021 cm–3 at 300 K. Electronic band structures calculated by density functional theory reveal a Weyl point with a chiral charge of +3 above the Fermi level. 

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5. Synthesis of α′′-Fe ₁₆ N ₂ ribbons with a porous structure

   https://doi.org/10.1039/c9na00008a  

   Liu, Jinming; Guo, Guannan; Zhang, Fan; Wu, Yiming; Ma, Bin; Wang, Jian-Ping (April 2019, Nanoscale Advances)

   The microstructure of FeCuB ribbons (∼20 μm thick) was modified to fabricate α′′-Fe 16 N 2 at a temperature as low as 160 °C. The ribbon samples were heat treated first at a temperature reaching 930 °C and then quenched down to room temperature. During the heat treatment, ribbon samples were oxidized, and hydrogen reduction was then conducted to remove the oxygen from the ribbon samples. The reduced ribbon samples had a porous structure, which improved the nitrogen diffusion efficiency and decreased the fabrication temperature of α′′-Fe 16 N 2 down to 160 °C. It was demonstrated that the techniques for microstructure control in this method including oxidation and reduction helped obtain the α′′-Fe 16 N 2 phase with high coercivity, thus manifesting this could be a promising technique for low-temperature nitridation on ribbons in general. 

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