Iaroslava Shakhova

The diverse functionalities of (oxy-)hydroxides, such as electrocatalytic activity of transition-metal oxy-hydroxides in the oxygen evolution reaction (OER) and ion exchange capabilities of layered double hydroxides (LDHs), continue to attract significant interest. However, these compounds are typically synthesized in aqueous solutions at room temperature, under hydrothermal conditions, or in mild vapor atmospheres. Here, we present a novel (oxy-)hydroxide synthesis technique called “vapor hydroxidation,” which is conducted in a highly concentrated water vapor atmosphere at elevated temperatures. Structural analysis revealed the formation of a new oxy-hydroxide, [Ba₂O_x(OH)_y]_0.55InO₂, with a misfit-layered structure, characterized by alternating incommensurate barium hydroxide bilayers and indium oxide blocks. Unlike known (oxy-)hydroxides, this oxy-hydroxide displays exceptional thermal stability, retaining hydroxide ions within its crystal structure up to approximately 700 °C. These features suggest promising potential for high-temperature proton conductivity, as demonstrated by an electrical conductivity of 5 × 10⁻⁴ S cm⁻¹ at 500 °C even under dry argon. Our “vapor hydroxidation” method thus opens up a new avenue for the development of proton-functional materials with unconventional chemical and electronic characteristics.

The Li_1.17Ni_0.17Mn_0.50Co_0.17O₂ Li-rich NMC positive electrode (cathode) for lithium-ion batteries has been coated with nanocrystals of the LiMn_1.5Co_0.5O₄ high-voltage spinel cathode material. The coating was applied through a single-source precursor approach by a deposition of the molecular precursor LiMn_1.5Co_0.5(thd)₅ (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) dissolved in diethyl ether, followed by thermal decomposition at 400 °C inair resulting in a chemically homogeneous cubic spinel. The structure and chemical composition of the coatings, deposited on the model SiO₂ spheres and Li-rich NMC crystallites, were analyzed using powder X-ray diffraction, electron diffraction, high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray (EDX) mapping. The coated material containing 12 wt.% of spinel demonstrates a significantly improved first cycle Coulombic efficiency of 92% with a high first cycle discharge capacity of 290 mAhg⁻¹. The coating also improves the capacity and voltage retention monitored over 25 galvanostatic charge–discharge cycles, although a complete suppression of the capacity and voltage fade is not achieved.

The use of aluminum alloy AA2024-T4 (Russian designation D16T) in applications requiring a high strength-to-weight ratio and fatigue resistance such as aircraft fuselage often demands the control and modification of surface properties. A promising route to surface conditioning of Al alloys is laser treatment. In the present work, the formation of ripples and conical microstructures under scanning with femtosecond (fs) laser pulses was investigated. Laser treatment was performed using 250 fs pulses of a 1033 nm Yb:YAG laser. The fluence of the pulses varied from 5 to 33 J/cm². The scanning was repeated from 1 to 5 times for different areas of the sample. Treated areas were evaluated using focused ion beam (FIB)- scanning electron microscopy (SEM) imaging and sectioning, energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), and confocal laser profilometry. The period of laser-induced periodic surface structures (LIPSS) and the average spacing of conical microstructures were deduced from SEM images by FFT. Unevenness of the treated areas was observed that is likely to have been caused by ablation debris. The structural and elemental changes of the material inside the conical microstructures was revealed by FIB-SEM and EDX. The underlying formation mechanisms of observed structures are discussed in this paper.

NASICON-structured Na ₃ V ₂ O _2x (PO ₄ ) ₂ F _3−2x (0 < x ≤ 1) solid solutions have been prepared using a microwave-assisted hydrothermal (MW-HT) technique.