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Honeycomb layered oxides constitute an emerging class of materials that show interesting physicochemical and electrochemical properties. However, the development of these materials is still limited. Here, we report the combined use of alkali atoms ($\rm Na$ and $\rm K$) to produce a mixed alkali honeycomb layered oxide material, namely, $\rm NaKNi_2TeO_6$. Via transmission electron microscopy measurements, we reveal the local atomic structural disorders characterised by aperiodic stacking and incoherency in the alternating arrangement of $\rm Na$ and $\rm K$ atoms. We also investigate the possibility of mixed electrochemical transport and storage of $\rm Na$ and $\rm K$ ions in $\rm NaKNi_2TeO_6$. In particular, we report an average discharge cell voltage of about $4\, \rm V$ and a specific capacity of around $80\, \rm mAh\, g^{-1}$ at low specific currents (i.e., $< 10\, \rm mA\, g^{-1}$) when a $\rm NaKNi_2TeO_6$-based positive electrode is combined with a room-temperature $\rm NaK$ liquid alloy negative electrode using an ionic liquid-based electrolyte solution. These results represent a step towards the use of tailored cathode active materials for dendrite-free electrochemical energy storage systems exploiting room-temperature liquid alkali metal alloy materials., 39 Pages, 7 Figures, 1 Cover Art

Oxide-ion conductors are important in various applications such as solid-oxide fuel cells. Although zirconia-based materials are widely utilized, there remains a strong motivation to discover electrolyte materials with higher conductivity that lowers the working temperature of fuel cells, reducing cost. Oxide-ion conductors with hexagonal perovskite related structures are rare. Herein, we report oxide-ion conductors based on a hexagonal perovskite-related oxide Ba7Nb4MoO20. Ba7Nb3.9Mo1.1O20.05 shows a wide stability range and predominantly oxide-ion conduction in an oxygen partial pressure range from 2 × 10−26 to 1 atm at 600 °C. Surprisingly, bulk conductivity of Ba7Nb3.9Mo1.1O20.05, 5.8 × 10−4 S cm−1, is remarkably high at 310 °C, and higher than Bi2O3- and zirconia-based materials. The high conductivity of Ba7Nb3.9Mo1.1O20.05 is attributable to the interstitial-O5 oxygen site, providing two-dimensional oxide-ion O1−O5 interstitialcy diffusion through lattice-O1 and interstitial-O5 sites in the oxygen-deficient layer, and low activation energy for oxide-ion conductivity. Present findings demonstrate the ability of hexagonal perovskite related oxides as superior oxide-ion conductors.

Most solid-state materials are composed of p-block anions, only in recent years the introduction of hydride anions (1s2) in oxides (e.g., SrVO2H, BaTi(O, H)3) has allowed the discovery of various interesting properties. Here we exploit the large polarizability of hydride anions (H–) together with chalcogenide (Ch2–) anions to construct a family of antiperovskites with soft anionic sublattices. The M3HCh antiperovskites (M = Li, Na) adopt the ideal cubic structure except orthorhombic Na3HS, despite the large variation in sizes of M and Ch. This unconventional robustness of cubic phase mainly originates from the large size-flexibility of the H– anion. Theoretical and experimental studies reveal low migration barriers for Li+/Na+ transport and high ionic conductivity, possibly promoted by a soft phonon mode associated with the rotational motion of HM6 octahedra in their cubic forms. Aliovalent substitution to create vacancies has further enhanced ionic conductivities of this series of antiperovskites, resulting in Na2.9H(Se0.9I0.1) achieving a high conductivity of ~1 × 10–4 S/cm (100 °C)., ソフトな陰イオンをもつ逆ペロブスカイト化合物で高速イオン伝導を達成. 京都大学プレスリリース. 2021-01-08.

Oxide-ion conductors are important in various applications such as solid-oxide fuel cells. Although zirconia-based materials are widely utilized, there remains a strong motivation to discover electrolyte materials with higher conductivity that lowers the working temperature of fuel cells, reducing cost. Oxide-ion conductors with hexagonal perovskite related structures are rare. Herein, we report oxide-ion conductors based on a hexagonal perovskite-related oxide Ba7Nb4MoO20. Ba7Nb3.9Mo1.1O20.05 shows a wide stability range and predominantly oxide-ion conduction in an oxygen partial pressure range from 2 × 10−26 to 1 atm at 600 °C. Surprisingly, bulk conductivity of Ba7Nb3.9Mo1.1O20.05, 5.8 × 10−4 S cm−1, is remarkably high at 310 °C, and higher than Bi2O3- and zirconia-based materials. The high conductivity of Ba7Nb3.9Mo1.1O20.05 is attributable to the interstitial-O5 oxygen site, providing two-dimensional oxide-ion O1−O5 interstitialcy diffusion through lattice-O1 and interstitial-O5 sites in the oxygen-deficient layer, and low activation energy for oxide-ion conductivity. Present findings demonstrate the ability of hexagonal perovskite related oxides as superior oxide-ion conductors., Oxide-ion conductors are important in various applications for clean energy. Here, authors report high oxide-ion conductivity of hexagonal perovskite-related oxide Ba7Nb3.9Mo1.1O20.05, which is ascribed to the interstitialcy diffusion and low activation energy for oxide-ion conductivity.

The degree and dynamics of translational control during mammalian development remain poorly understood. Here we monitored translation of the mammalian genome as cells become specified and organize into tissues in vivo. This identified unexpected and pervasive translational regulation of most of the core signalling circuitry including Shh, Wnt, Hippo, PI3K and MAPK pathways. We further identify and functionally characterize a complex landscape of upstream open reading frames (uORFs) across 5′-untranslated regions (UTRs) of key signalling components. Focusing on the Shh pathway, we demonstrate the importance of uORFs within the major SHH receptor, Ptch1, in control of cell signalling and neuronal differentiation. Finally, we show that the expression of hundreds of mRNAs underlying critical tissue-specific developmental processes is largely regulated at the translation but not transcript levels. Altogether, this work reveals a new layer of translational control to major signalling components and gene regulatory networks that diversifies gene expression spatially across developing tissues., Gene expression is regulated at several levels, including through the modulation of protein translation. Here the authors find that translation control diversifies gene expression between developing tissues and regulates major signalling pathways through a complex landscape of upstream open reading frames (uORFs).

Oxide-ion conductors have found applications in various electrochemical devices, such as solid-oxide fuel cells, gas sensors, and separation membranes. Dion–Jacobson phases are known for their rich magnetic and electrical properties; however, there have been no reports on oxide-ion conduction in this family of materials. Here, for the first time to the best of our knowledge, we show the observation of fast oxygen anionic conducting behavior in CsBi2Ti2NbO10−δ. The bulk ionic conductivity of this Dion–Jacobson phase is 8.9 × 10−2 S cm−1 at 1073 K, a level that is higher than that of the conventional yttria-stabilized zirconia. The oxygen ion transport is attributable to the large anisotropic thermal motions of oxygen atoms, the presence of oxygen vacancies, and the formation of oxide-ion conducting layers in the crystal structure. The present finding of high oxide-ion conductivity in rare-earth-free CsBi2Ti2NbO10−δ suggests the potential of Dion–Jacobson phases as a platform to identify superior oxide-ion conductors., Oxide ion conductors are an exciting class of materials with applications in various domains. Here, the authors show that Dion–Jacobson Phases are a structure supporting high O2− mobility. The bulk conductivity of CsBi2Ti2NbO10−δ even exceeds that of YSZ, offering new possibilities in electrolyte discovery.

Perovskite oxides can host various anion-vacancy orders, which greatly change their properties, but the order pattern is still difficult to manipulate. Separately, lattice strain between thin film oxides and a substrate induces improved functions and novel states of matter, while little attention has been paid to changes in chemical composition. Here we combine these two aspects to achieve strain-induced creation and switching of anion-vacancy patterns in perovskite films. Epitaxial SrVO3 films are topochemically converted to anion-deficient oxynitrides by ammonia treatment, where the direction or periodicity of defect planes is altered depending on the substrate employed, unlike the known change in crystal orientation. First-principles calculations verified its biaxial strain effect. Like oxide heterostructures, the oxynitride has a superlattice of insulating and metallic blocks. Given the abundance of perovskite families, this study provides new opportunities to design superlattices by chemically modifying simple perovskite oxides with tunable anion-vacancy patterns through epitaxial lattice strain., Using strain to control oxynitride properties. 京都大学プレスリリース. 2020-12-01., 原子空孔の配列を制御する新手法の発見. 京都大学プレスリリース. 2020-12-02.