High Proton Conduction in the Octahedral Layers of Fully Hydrated Hexagonal Perovskite-Related Oxides.

Proton conductors have potential applications such as fuel cells, electrolysis cells, and sensors. These applications require new materials with high proton conductivity and high chemical stability at intermediate temperatures. Herein we report a series of new hexagonal perovskite-related oxides, BaAlSnO ( = Gd, Dy, Ho, Y, Er, Tm, and Yb).

High Conductivity and Diffusion Mechanism of Oxide Ions in Triple Fluorite-Like Layers of Oxyhalides.

Oxide ion conductors are attractive materials because of their wide range of applications, such as solid oxide fuel cells. Oxide ion conduction in oxyhalides (compounds containing both oxide ions and halide ions) is rare. In the present work, we found that Sillén oxychlorides, BiTeLuOCl ( = 0, 0.

Synthesis, crystal structure and investigation of ion-exchange possibility for sodium tellurate NaTeO(OH).

A new sodium tellurate has been hydrothermally synthesized and comprehensively analysed using spectroscopic and thermogravimetric techniques, resulting in the determination of its composition as NaTeO(OH). The analysis of synchrotron X-ray and neutron diffraction data indicates that NaTeO(OH) has a crystal structure similar to that of the previously reported tellurate, KTeO(OH), with the space group 2/ (No. 14).

Strongly Enhanced Polarization in a Ferroelectric Crystal by Conduction-Proton Flow.

Ion conductors comprising noncentrosymmetric frameworks have emerged as new functional materials. However, strongly correlated polarity functionality and ion transport have not been achieved. Herein, we report a ferroelectric proton conductor, KMnN(CN)·HO (), exhibiting the strong correlation between its polar skeleton and conductive ions that generate anomalous ferroelectricity via the proton-bias phenomenon.

High proton conductivity within the 'Norby gap' by stabilizing a perovskite with disordered intrinsic oxygen vacancies.

Proton conductors are attractive materials with a wide range of potential applications such as proton-conducting fuel cells (PCFCs). The conventional strategy to enhance the proton conductivity is acceptor doping into oxides without oxygen vacancies. However, the acceptor doping results in proton trapping near dopants, leading to the high apparent activation energy and low proton conductivity at intermediate and low temperatures.

Thiocyanate-Stabilized Pseudo-cubic Perovskite CH(NH)PbI from Coincident Columnar Defect Lattices.

α-FAPbI (FA = CH(NH)) with a cubic perovskite structure is promising for photophysical applications. However, α-FAPbI is metastable at room temperature, and it transforms to the δ-phase at a certain period of time at room temperature. Herein, we report a thiocyanate-stabilized pseudo-cubic perovskite FAPbI with ordered columnar defects (α'-phase).

LaGaSO: A Rare-Earth Gallium Oxysulfide with Disulfide Ions.

Band gap engineering using multiple anions is an established approach to novel photocatalysts that exhibit suitable band gap energies for water splitting and high photocorrosion resistance. However, few studies have been conducted on photocatalysts with polyanions, including polychalcogenide ions. Here, we present a new quaternary gallium oxysulfide with disulfide pairs (S), LaGaSO, grown out of a KI molten salt.

Hidden chemical order in disordered BaNbMoO revealed by resonant X-ray diffraction and solid-state NMR.

The chemical order and disorder of solids have a decisive influence on the material properties. There are numerous materials exhibiting chemical order/disorder of atoms with similar X-ray atomic scattering factors and similar neutron scattering lengths. It is difficult to investigate such order/disorder hidden in the data obtained from conventional diffraction methods.

Supramolecular multi-electron redox photosensitisers comprising a ring-shaped Re(i) tetranuclear complex and a polyoxometalate.

Redox photosensitisers (PSs) play essential roles in various photocatalytic reactions. Herein, we synthesised new redox PSs of 1 : 1 supramolecules that comprise a ring-shaped Re(i) tetranuclear complex with 4+ charges and a Keggin-type heteropolyoxometalate with 4- charges. These PSs photochemically accumulate multi-electrons in one molecule (three or four electrons) in the presence of an electron donor and can supply electrons with different reduction potentials.

Recent developments in oxide ion conductors: focusing on Dion-Jacobson phases.

Oxide-ion conductors, also known as "oxygen ion conductors," have garnered significant attention in recent years due to their extensive applications in a variety of electrochemical devices, including oxygen concentrators, solid-oxide fuel cells (SOFCs), and solid oxide electrolysis cells. The key to improving the performance of these devices is the creation of novel oxide-ion conductors. In this feature article, we discuss the recent developments of new structural families of oxide-ion conductors and of the Dion-Jacobson-type layered oxide-ion conductors with a particular emphasis on CsTiNbO ( = Bi and lanthanoids; represents oxygen-vacancy content) and their solid solutions.

Ge-Containing Oxide-Ion Conductors with CaEuGeO-Type Structure Discovered by the Bond-Valence Method and Experiments.

In the present work, we have discovered the first example of a CaEuGeO-type oxide-ion conductor, CaSmGeO. The CaEuGeO-type structure was selected by screening 624 Ge-containing materials by the bond-valence-based-energy calculations. CaEuGeO-type CaEuGeO, CaGdGeO, and a new material CaSmGeO were synthesized.

Highly Electron-Doped TaON Single-Crystal Growth by a High-Pressure Flux Method.

Transition-metal oxynitrides have a variety of functions such as visible light-responsive catalysts and dielectric materials, but acquiring single crystals necessary to understand inherent properties is difficult and is limited to relatively small sizes (<10 μm) because they easily decompose at high temperatures. Here, we have succeeded in growing platelet single crystals of TaON with a typical size of 50 × 100 × 10 μm under a high pressure and high temperature (6 GPa and 1400 °C) using a LiCl flux. Such a harsh condition, in contrast to powder samples synthesized under mild conditions, resulted in the introduction of a large amount of oxygen vacancies ( = 0.

Simultaneous Reduction of Proton Conductivity and Enhancement of Oxide-Ion Conductivity by Aliovalent Doping in BaNbMoO.

Hexagonal perovskite-related oxides have garnered a great deal of research interest because of their high oxide-ion conductivity at intermediate temperatures, with BaNbMoO being a notable example. However, concomitant proton conduction in BaNbMoO may cause a decrease in power efficiency when used as the electrolyte in conventional solid oxide fuel cells. Here, through investigations of the transport and structural properties of BaNbWMoO ( = 0-0.

Synthesis of Hydride-Doped Perovskite Stannate with Visible Light Absorption Capability.

Narrow-gap semiconductors with visible light absorption capability have attracted attention as photofunctional materials. H-doped BaSnYO containing Sn(II) species was recently reported to absorb visible light up to 600 nm, which represents the first demonstration of oxyhydride-based visible-light-absorbers. In the present study, a more detailed investigation was made to obtain information on the synthesis and properties of H-doped perovskite-type stannate with respect to the A-site cation of the material and the preparation conditions.

High Oxide-Ion Conductivity in a Hexagonal Perovskite-Related Oxide Ba Ta Mo O with Cation Site Preference and Interstitial Oxide Ions.

Solid oxide-ion conductors are crucial for enabling clean and efficient energy devices such as solid oxide fuel cells. Hexagonal perovskite-related oxides have been placed at the forefront of high-performance oxide-ion conductors, with Ba Nb Mo O (x = 0-0.1) being an archetypal example.

Electrochemical Crystal Growth of Titanium Oxyfluorides-A Strategy for Development of Electron-Doped Materials.

We report on the growth of single crystals of an electron-doped titanium oxyfluoride, LiTi(O,F), employing high-temperature electrolysis of TiO with a eutectic LiMoO-LiF melt. Greenish octahedral-shaped crystals (∼30 μm in size) with a cubic rocksalt-type structure were successfully obtained by precisely tuning the applied voltage. The temperature-dependent magnetic susceptibility data revealed a paramagnetic behavior at low temperatures, ensuring the presence of Ti ions (mean valence number of +3.

Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNiTeO.

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 (Na and K) to produce a mixed-alkali honeycomb layered oxide material, namely, NaKNiTeO.

Kinetically Stabilized Cation Arrangement in Li YCl Superionic Conductor during Solid-State Reaction.

The main approach for exploring metastable materials is via trial-and-error synthesis, and there is limited understanding of how metastable materials are kinetically stabilized. In this study, a metastable phase superionic conductor, β-Li YCl , is discovered through in situ X-ray diffraction after heating a mixture of LiCl and YCl powders. While Cl arrangement is represented as a hexagonal close packed structure in both metastable β-Li YCl synthesized below 600 K and stable α-Li YCl above 600 K, the arrangement of Li and Y in β-Li YCl determined by neutron diffraction brought about the cell with a 1/√3 a-axis and a similar c-axis of stable α-Li YCl .

Protonic Conduction in the BaNdInO Structure Achieved by Acceptor Doping.

The potential of calcium-doped layered perovskite compounds, BaNd Ca InO (where is the excess Ca content), as protonic conductors was experimentally investigated. The acceptor-doped ceramics exhibit improved total conductivities that were 1-2 orders of magnitude higher than those of the pristine material, BaNdInO. The highest total conductivity of 2.

High oxide-ion conductivity through the interstitial oxygen site in BaNbMoO-based hexagonal perovskite related oxides.

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.

Hydride-based antiperovskites with soft anionic sublattices as fast alkali ionic conductors.

Most solid-state materials are composed of p-block anions, only in recent years the introduction of hydride anions (1s) in oxides (e.g., SrVOH, BaTi(O,H)) has allowed the discovery of various interesting properties.

Ionic conduction mechanism in Ca-doped lanthanum oxychloride.

The mechanism of ionic conduction in Ca-doped lanthanum oxychloride (LaOCl) was investigated using first-principles calculations based on density functional theory. The calculations of the point defect formation energies suggest that Cl ion vacancies and substituted Ca ions at La sites were dominant point defects. Although the migration energy of an O ion is 0.

Strain-induced creation and switching of anion vacancy layers in perovskite oxynitrides.

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.