The influence of non-stoichiometry in the crystalline phase of V6O13 on the set of magnetic and electronic transitions and impedances in a magnetic field was studied. V6O13 films were produced by cathodic arc sputtering method from vanadium target in oxygen atmosphere. Crystal structure of the films and crystallite sizes were determined by X-ray diffraction, Raman spectroscopy and atomic force microscopy. Magnetic properties by ZFC and FC mode and electrical properties were investigated. Non-stoichiometry of oxygen leads to the formation of VO2 и V2O3 microregions. Temperature dependences of magnetic susceptability and electrical resistivity have small hysteresis near room and points of extremum in the regions of metal-insulator and magnetic phase transitions. As the temperature decreases, the relaxation time increases; the relaxation is driven by dielectric losses. The impedance decreases in the magnetic field at the temperatures of phase transitions, and the correlation between magnetic and electrical properties is established. The possibility of regulating the metal-dielectric transition under laser illumination has been revealed.

The synthesis of vanadium oxide compounds, V218O3-x, with oxygen non-stoichiometry and heavy oxygen isotope doping (18O), was achieved via the cathode arc sputtering method. The microstructural characteristics and stoichiometric properties of the resulting nanocrystalline films were examined using X-ray diffraction, atomic force microscopy and Rutherford backscatter spectrometry. The concentration of defects leading to the suppression of the structural and electronic metal-insulator transition was evaluated through Raman spectroscopy and the analysis of electrophysical properties. A semi-empirical simulation of the lattice dynamics of vanadium oxide was also performed. Notable temperature anomalies in resistance, impedance, and relaxation time were observed. A model involving the deformation of octahedra and the splitting of oxygen vacancies multiplets was proposed to explain the formation of impurity subbands. Furthermore, a change in the sign of magnetoresistance and magnetoimpedance at specific temperatures, along with the effect of photoconductivity, was discovered.

Perpendicular magnetic anisotropy (PMA) plays an important role in different spintronic devices. The rapid development of spintronics requires a better understanding of the nature and mechanisms of the PMA formation. In our article, we demonstrate the potential of studying PMA by in-situ polarized neutron reflectometry combined with pulsed laser deposition. Using these techniques, we show the formation of out-of-plane anisotropy in thin CoFeB films (1.8 nm) with a capping Mo layer. Investigating thick (5.3 nm}) and thin (0.5 nm) molybdenum films, we demonstrate that in both cases, PMA was established in bilayer structures without any thermal annealing. Also, we demonstrate how an additional silicon layer grown over the CoFeB/Mo bilayer can critically alter the magnetic properties of the sample. Such studies are possible only through the unique combination of the growth method with the in-situ polarized neutron reflectometry measurement technique. We believe that this approach will open up broad opportunities for the development and investigation of new spintronic devices.

The variety of colors found in wild mushrooms is remarkable: Yellow chanterelles, red fly agarics, violet wood blewits, blue indigo milk caps, green verdigris roundheads, brown bay cups, and black dead man's fingers are just a few examples. The pigments responsible for these hues belong to various classes of chemical compounds. Identifying them is a significant challenge, often necessitating advanced equipment and unconventional sample preparation methods. This study shows that direct spectroscopic measurements on living organisms through Raman scattering can provide a wealth of valuable information regarding their pigments. Raman spectroscopy was used to successfully identify carotenoids, melanins, polyketides (which include pulvinic acid derivatives, styrylpyrones, and anthraquinones), and polyphenol-metal complexes in the spores and fruiting bodies of 68 different species of mushrooms. Such an approach is particularly sensitive to carotenoids and conjugated polyenals, allowing for the estimation of their concentrations and structural parameters. The research demonstrates that Raman spectroscopy can serve as a highly effective tool for investigating colored biological materials in vivo.

Implementation of neuromorphic hardware is a promising way to improve the computing efficiency and decrease the energy consumption of artificial neural networks. For this purpose, electronic elements emulating the behavior of synapses and neurons have to be developed. In order to realize electronic artificial neurons, threshold resistive switches or memristors can be efficiently used. One of the most widespread materials for threshold switches is vanadium dioxide due to its property to demonstrate the metal-insulator transition at a temperature about 70 °C. However, the processes of VO_2 synthesis are quite restrictive in temperature and gas atmosphere conditions, which hinders its integration into CMOS fabrication. In this work, we propose a new method of VO_2 synthesis: reactive pulsed laser deposition from metallic V target in oxygen atmosphere at room temperature, followed by vacuum annealing. Our method enables target synthesis of an appropriate VO_2 phase in a polycrystalline thin film form by finely tuning oxygen pressure during room temperature deposition, which allows to relax the equipment demands, such as high temperature heating in oxygen. Successful targeted VO_2 synthesis under fabrication conditions close to back-end-of-line CMOS production, achieved in this work, show the way toward its large-scale microelectronic integration for neuromorphic hardware creation.

A polyacrylic acid hydrogel containing Ce4+ ions acting as a catalyst for the Belousov-Zhabotinsky reaction with self-healing and self-propelled properties was prepared by a one-pot synthesis. By using cerium ammonium nitrate as a radical polymerization initiator, a significant simplification of the synthesis of stimuli-responsive polymers was achieved. The compressive strain and elastic modulus were calculated to describe the mechanical properties of the hydrogel during compression.

The development of ferromagnet/heavy metal thin-film structures, such as CoFeB/Mo, with spin-orbit interaction requires advanced methods for their production and study. Polarized neutron reflectometry (PNR) provides unique insights into the evolution of magnetic properties, especially when applied in-situ during the growth process. Pulsed laser deposition (PLD) is a versatile method for producing magnetic thin films, and combining PLD with in-situ PNR measurements offers new possibilities for their investigation. In this work, we developed a compact vacuum chamber integrated into the neutron instrument, enabling step-by-step deposition and in-situ PNR measurements. A multilayer Mo/[CoFeB/Mo]12 structure was grown, and neutron reflectivity curves measured after each cycle revealed the gradual evolution of sample properties. A weak magnetic field response suggested the potential formation of perpendicular magnetic anisotropy (PMA) at CoFeB/Mo interfaces. Additionally, a single CoFeB film was annealed up to 450°C, followed by the deposition of a ~5 Å Mo layer. PNR measurements in magnetic fields of 0.01 T and 0.75 T showed a significant increase in in-plane magnetization, confirming PMA formation. Thus, we demonstrate the first successful operation of a combined PLD and in-situ PNR system, showcasing its capabilities for characterizing single-layer CoFeB and multilayer CoFeB/Mo thin-film structures.

This study investigates the effect of polyvinylidene fluoride–CoFe2O4 (PVDF-CFO) composite film thickness on their supramolecular structure, phase composition, and dielectric properties. The composites were synthesized from PVDF with CFO nanoparticles using the Dr. Blade method to obtain film thicknesses ranging from 15 to 58 μm. The data obtained show that the thinner film (15 μm) has a higher β-phase content compared to the thicker films (58 μm), as confirmed by FTIR and Raman spectroscopy. Scanning electron microscopy (SEM) showed that increasing film thickness within the studied range leads to the development of larger spherulitic structures and increased porosity. Atomic force microscopy (AFM) analysis also showed that thicker films have higher tensile strength due to their larger cross-sectional area, while thinner films exhibit lower elasticity. A more uniform microstructure and an increased electroactive phase in thin films result in increased permittivity, which is critical for PVDF-based sensors and energy devices.

Vanadium oxide xerogel samples (V2O5 center dot nH2O) were successfully synthesized using a liquid phase reaction between alpha-V2O5 and H2O2, as well as through the interaction of amorphous V2O5 films with atmospheric water. The samples were systematically investigated by X-ray diffraction and Raman spectroscopy. Temperature-dependent studies confirmed the existence of two distinct phases. Depending on synthesis and processing protocols, either phase can be stabilized in ambient conditions. It was proved that the formation of a high-temperature phase from amorphous vanadium oxide previously led to some misinterpretations associated with the high-pressure 6-V2O5 polymorph. While current structural models of vanadium oxide xerogel provide some insights, our findings underscore the exciting potential for refining and expanding these models in future research endeavors.

In this paper, based on the analysis of Raman spectroscopy data, the kinetics of the disproportionation reaction process (GeOx → (1−x/2)Ge + (x/2)GeO2) of an amorphous GeOx film during furnace annealing were studied. An approximation of the experimental kinetics of the disproportionation reaction to the theoretical Kolmogorov–Johnson–Mel–Avrami dependence has been carried out. By analyzing the temperature dependence of the formation time of amorphous germanium clusters, the activation energy of the formation process was obtained, which amounted to 0.9 ± 0.1 eV. In addition, it was found that the position of the Raman peak from amorphous germanium nanoclusters depends on their size. Thus, the phonon localization model can be applied not only to germanium nanocrystals but also to amorphous germanium clusters in the case of their ultra-small sizes (less than 1.5 nm), which is less than the phonon correlation length in amorphous germanium.

We report a new facile method for the synthesis of prolate cobalt ferrite nanoparticles without additional stabilizers, which involves a co-precipitation reaction of Fe3+ and Co2+ ions in a static magnetic field. The magnetic field is demonstrated to be a key factor for the 1D growth of cobalt ferrite nanocrystals in the synthesis. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy are applied to characterize the morphology and structure of the obtained nanoparticles. According to TEM, they represent nanorods with a mean length of 25 nm and a diameter of 3.4 nm that have a monocrystalline structure with characteristic plane spacing of 2.9 Å. XRD and Raman spectroscopy confirm the spinel CoFe2O4 structure of the nanorods. After aging, the synthesized nanorods exhibit maximum saturation magnetization and coercivity equal to 30 emu/g and 0.3 kOe, respectively. Thus, the suggested method is a simple and “green” way to prepare CoFe2O4 nanorods with high aspect ratios and pronounced magnetic properties, which are important for various practical applications, including biomedicine, energy storage, and the preparation of anisotropic magnetic nanocomposites.

We summarize the current knowledge on crystal structures, synthesis, applications, and Raman spectroscopy of Wadsley phases of vanadium oxide, including VO2 (B), V6O13, V4O9, V3O7, and V2O5. While these oxides have garnered significant attention for potential energy storage applications and have been studied for decades, there remains inconsistency in data regarding their characteristic Raman spectra. To address this, we synthesized a series of Wadsley phases by physical vapor deposition of amorphous vanadium oxide films and subsequent annealing in a controlled environment. X-ray diffraction studies confirmed the formation of VO2 (B), V6O13, V4O9, and V3O7. We meticulously measured the room-temperature Raman spectra of these phases, offering robust reference data for the easy identification of vanadium oxides in unknown samples. Finally, we studied low-temperature phase transitions in VO2 (B) and V6O13.

Elements of microfluidic systems created by 3D printing offer numerous advantages, such as rapid manufacturing, low cost, and the ability to create complex 3D channel topologies. Their parameters and performance can be quickly adjusted by editing the model loaded into the printer. However, the mechanical properties of polymers used for printing are often poorly documented and can significantly change over time due to aging, relaxation, or creep effects, leading to unexpected behaviour of 3D-printed devices. To address this issue, we performed a complete mechanical characterization of the samples made by 3D printing, including stress relaxation and creep tests, at different time intervals after printing. The determined properties of the material allowed us to model the mechanical and hydrodynamical performance of the 3D-printed microfluidic device, which we demonstrate using an example of a fully printed check valve specially developed for use in microfluidic systems. This approach allows easy quantitative evaluation of the optimal production cycle and lifetime of 3D-printed microfluidic devices.

Microreactor chemistry has evolved over the past two decades, showing great promise in the chemical industry, pharmaceuticals, fine chemicals, and in chemical synthesis research. Although, the microfluidic systems have found wide practical applications, there is little information regarding their industrial adaptation in catalytic chemistry. The microreactor chemistry presents myriad optimization opportunities for gas–liquid catalytic processes, particularly in the context of hydroformylation, which requires high pressures of toxic gases and temperatures. The current review highlights advantages of continuous flow for hydroformylation and related reactions, which are of great importance as a root for production of oxygenates. These reactions nowadays have increasing role in processing renewable raw materials as a sustainable high atomic-efficiency route. The review reports the most recent advancements in microfluidic technology with a focus on the high-pressure conditions and applicable spectral methods for in situ and operando diagnostics in the biphasic segmented flow regime.

With the declining number of neutron sources in the world and the decommissioning of research reactors, there is a growing interest in developing compact neutron sources. The DARIA project involves the use of a proton beam accelerated to an energy of 13 MeV, which creates a neutron beam through the ( p , n ) nuclear reaction with a beryllium target. The reaction yield is 3 neutrons per 1000 protons, releasing most of the proton-beam energy as heat in the target, which can cause its destruction if sufficient heat removal is not provided. To address this issue, we develop a rotating water-cooled beryllium target system capable of efficiently removing heat from the target’s inner (water facing) surface. We conduct numerical calculations to determine the coolant rate and pressure limits, as well as the corresponding flows leading to target destruction. Thermodynamic calculations make it possible to estimate the system’s average temperature and peak local temperatures due to high-energy pulses.

The temperature dependence of the resistivity of titanium oxynitride TiNxOy thin films with different oxygen and nitrogen content obtained by atomic layer deposition was investigated. We found that the resistance of all films monotonically decreased with increasing temperature and varied within a wide range depending on the chemical composition and thickness of the film. The technology for obtaining a compact temperature sensor of wide range from helium to room temperature based on 40-nm thick TiN0.87O0.97 is presented.

Pulsed laser deposition of nanostructured molybdenum sulfide films creates specific nonequilibrium growth conditions, which improve the electrocatalytic properties of the films in a hydrogen evolution reaction (HER). The enhanced catalytic performance of the amorphous a-MoSx (2 ≤ x ≤ 3) matrix is due to the synergistic effect of the Mo nanoparticles (Mo-NP) formed during the laser ablation of a MoS2 target. This work looks at the possibility of employing a-MoSx/NP-Mo films (4 and 20 nm thickness) to produce hydrogen by photo-stimulated HER using a p-Si cathode. A simple technique of pulsed laser p-Si doping with phosphorus was used to form an n+p-junction. Investigations of the energy band arrangement at the interface between a-MoSx/NP-Mo and n+-Si showed that the photo-HER on an a-MoSx/NP-Mo//n+p-Si photocathode with a 20 nm thick catalytic film proceeded according to a Z-scheme. The thickness of interfacial SiOy(P) nanolayer varied little in photo-HER without interfering with the effective electric current across the interface. The a-MoSx/NP-Mo//n+p-Si photocathode showed good long-term durability; its onset potential was 390 mV and photocurrent density was at 0 V was 28.7 mA/cm2. The a-MoSx/NP-Mo//n+p-Si photocathodes and their laser-based production technique offer a promising pathway toward sustainable solar hydrogen production.

The temperature dependence of the resistivity of titanium oxynitride TiNxOy thin films with different oxygen and nitrogen content obtained by atomic layer deposition was investigated. We found that the resistance of all films monotonically decreased with increasing temperature and varied within a wide range depending on the chemical composition and thickness of the film. The technology for obtaining a compact temperature sensor of wide range from helium to room temperature based on 40 nm thick TiN0.87O0.97 is presented. Keywords: titanium oxide-nitride, temperature sensors, thin films, atomic layer deposition, integrated circuit components.

A thin film of vanadium oxide Magnéli phase V4O7 was produced using cathodic arc sputtering. X-ray diffraction, Rutherford backscattering spectrometry and Raman investigations confirmed the formation of this phase. The Raman spectrum of V4O7 differs considerably from the spectrum of another Magnéli oxide, V3O5, showing that Raman spectroscopy is an excellent tool for distinguishing between these two phases. Temperature-dependent Raman measurements revealed a significant change of the spectra near the V4O7 metal–insulator phase transition.

We have designed, built, and tested two cells for in situ and, potentially, operando X-ray absorption spectroscopy experiments in transmission and fluorescence modes. The cells were developed for high-pressure and high-temperature conditions to study the catalytic processes under relevant industrial conditions. Operation of the cells was tested for Ru and Rh-based homogeneous and heterogeneous catalytic systems. Using synchrotron-based in situ X-ray absorption spectroscopy we tracked the evolution of active metal species during catalytic reactions. Our setup proved that it was capable to investigate liquid-state homogeneous and heterogenous systems under elevated temperatures, high pressures of reactive gasses, and in the presence of corrosive reagents.