The aim of this study was to investigate the tribological behaviour, of a reactive-sintered (Ti0.82Zr0.04Nb0.08Hf0.03Ta0.03)B2 + (Ti0.49Zr0.12Nb0.13Hf0.11Ta0.15)C composite using linear reciprocating testing combined with fractographic analysis. The composite exhibited a high relative density (99.8%) and a homogeneous microstructure with average grain sizes of 3.4 μm for the boride and 2.2 μm for the carbide phase. Both grains exhibited excellent nanohardness, with average values of 41.3 GPa for the boride and 38.3 GPa for the carbide phase. The average coefficient of friction remained stable at 0.65 and 0.59 under applied loads of 5 and 25 N, respectively, after 5000 s of testing, whereas increasing the load to 50 N reduced the coefficient of friction to 0.48. In contrast, the specific wear rate increased with applied load, rising from 1.87 × 10⁻⁷ mm³/N·m at 5 N to 1.64 × 10⁻⁶ mm³/N·m at 25 N and 2.64 × 10⁻⁶ mm³/N·m at 50 N.

In this study, an Al2O3-ZrO2 ceramic composite reinforced with WC was developed and characterised. The material was synthesized by spark plasma sintering (SPS) at 1600 degrees C under an argon atmosphere. Phase composition and microstructural features were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and aberration-corrected scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). The composite achieved a near-theoretical relative density (similar to 100 %) and a Young's modulus exceeding 90 % of the theoretical value. It consists primarily of Al2O3, WC, and ZrO2 (tetragonal and monoclinic phases), with a minor W2C phase. A homogeneous, ultrafine microstructure was observed, with average grain sizes of 0.44 +/- 0.10 mu m for Al2O3, 0.33 +/- 0.10 mu m for WC, and 0.37 +/- 0.15 mu m for ZrO2. No processing defects, such as porosity, abnormal grain growth, or large agglomerates, were detected, and grain boundary analysis revealed clean interfaces without impurity segregation, indicating high-quality intergranular bonding.

In this study, an Al2O3–ZrO2 ceramic composite reinforced with WC was developed and characterised. The material was synthesised by spark plasma sintering (SPS) at 1600 °C under an argon atmosphere. Phase composition and microstructural features were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and aberration-corrected scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). The composite achieved a near-theoretical relative density (∼100%) and a Young’s modulus exceeding 90% of the theoretical value. It consists primarily of Al2O3, WC, and ZrO2 (tetragonal and monoclinic phases), with a minor W2C phase. A homogeneous, ultrafine microstructure was observed, with average grain sizes of 0.44 ± 0.10 μm for Al2O3, 0.33 ± 0.10 μm for WC, and 0.37 ± 0.15 μm for ZrO2. No processing defects, such as porosity, abnormal grain growth, or large agglomerates, were detected, and grain boundary analysis revealed clean interfaces without impurity segregation, indicating high-quality intergranular bonding.

Sn-based Sn-Ag-Cu (SAC) solders are a great achievement of the scientific studies to replace the hazardous Pb-contained commercial solders. Nevertheless, the higher melting temperature comparing to the convenient Pb-Sn solders leads to the mechanical reliability issues of the lead-free solder joints due to larger Sn-Cu intermetallic compounds (IMCs), formed during the soldering process. In this work, the effects of minor additions of nanosized ceramic SiO2 and ZrO2 particles coated with Ni into the Sn–3.5Ag solder joints on their microstructure and shear strength has been studied. The morphology of the nanoparticles has been analyzed by transmission electron microscopy. Furthermore, SEM micrograph with EDS elemental analysis confirmed presence of Ni after the sputtering procedure on the surface of ceramic nanoparticles. The solder joints were produced in a sandwich form, where the nanopowders were mixed with a commercial flux and placed between the Sn–3.5Ag foil and Cu plate. The microstructure of the produced solder joints has been investigated using the scanning electron microscope. The discontinuous scallop-type shape of the interface IMC layer between the solder and substrate in the Sn–3.5Ag solder joint was changed into a more planar-type shape in those with nanosized additons. The major improvements of the interfacial layer shape were indicated for samples contained 0.5 wt% of nanosized inclusions, while the thickness of interfacial IMC layer decreased mostly gradually with increasing of nanoparticles up to 1 wt%. The shear strength of solder joints with nanosized additons was significantly enhanced from circa 30 MPa to circa 40 MPa.

Transition metal monoborides represent a structurally diverse class of materials known for their excellent thermal stability and mechanical properties. Synthesis by magnetron sputtering at temperatures similar to 500 degrees C usually results in the development of highly disordered or amorphous films. In this work we investigate the structural evolution of sputtered TaB1+Delta films induced by vacuum annealing. High-resolution scanning transmission electron microscopy reveals that crystallization of the disordered material into orthorhombic TaB-Cmcm structure is accompanied by formation of (110) stacking faults promoting the development of crystalline twins. The slight boron overstoichiometry in the films is accommodated by the structure through incorporation of B-rich planar defects resulting in local formation of hexagonal TaB2-P6/mmm phase. Experimental results are supported by density functional theory calculations demonstrating that twinning in the TaB-Cmcm structure is energetically favorable and thus a natural phenomenon. Importantly, our results indicate that overstoichiometry in TaB1+Delta is not likely to be caused by Ta vacancies, suggesting that planar and intergrowth-type defects represent the dominant mechanisms for incorporation of excess B.

The small-scale strength of a dual-phase high-entropy ceramic was investigated using micro-cantilever bending tests combined with linear beam theory, Weibull statistical analysis, and micro-and nano-fractography. The studied material was a high-entropy boride/carbide ceramic composite with an average grain size of approximately 1 mu m, synthesized by boro-carbothermal reduction and sintered by spark plasma sintering at 2000 degrees C under the pressure of 70 MPa for 10 min. Thirty micro-cantilevers were fabricated by focused ion beam (FIB) from a carefully polished surface at random locations to include both carbide and boride grains, as well as grain and phase boundaries within the beam volume. The measured bending strength ranged from 3.0 to 9.8 GPa, corresponding to a Weibull modulus of m = 3.3 and a characteristic strength of sigma 0 = 6.6 GPa. Fractographic analysis revealed that the fracture typically initiated at grain boundaries of differing character, size, and orientation. The spatial distribution of fracture origins along the cantilever length closely follows a Weibull-type statistical distribution, indicating that Weibull theory is also applicable to the microscale. Furthermore, the measured sizes of grain boundaries at the fracture origins (0.1-1.2 mu m) are in good agreement with values predicted using the Griffith criterion.

The synthesis of Co-ZIF polymorphs (C10H16N5O3/2Co, C8H10N4Co, and their mixture) was realized in aqueous medium under mild conditions. The morphology, crystalline and porous structure of products were investigated in detail by a range of diverse methods including scanning electron microscopy, X-ray diffraction, and low-temperature nitrogen adsorption-desorption. Visualization of the obtained metal-organic particles by SEM proved that variation of reaction mixture composition along with the metal precursor addition strategy opens up new opportunities for preparation of leaf-like, cuboid, pitaya-like, and rhombic dodecahedron Co-ZIFs. Evolution of two- to three-dimensional crystallographic structures, which takes place with the gradual increase of imidazolate ligand to metal precursor molar ratio, was confirmed by X-ray diffraction studies. According to the low-temperature nitrogen adsorption-desorption analysis, structural transformation is accompanied by a substantial increase of surface area and pore volume of the prepared Co-ZIFs. Equilibrium studies of methyl orange sorptive removal by the synthesized materials from aqueous medium proved that despite the higher specific surface area and developed porosity of the Co-ZIF with rhombic dodecahedron morphology, it demonstrates much lower sorption of dye than leaf-like, cuboid, and pitaya-like Co-ZIFs. The SEM analysis indicated that sorptive uptake of methyl orange by the leaf-like and cuboid Co-ZIFs leads to the formation of sponge-like frameworks made up of nano-sized granular structures. Meanwhile, X-ray diffraction and low-temperature nitrogen adsorption-desorption studies confirmed the formation of the rhombic dodecahedron crystalline phase and the evolution of porous structure.

Silicon is considered as a highly promising anode material for lithium-ion batteries because of its exceptionally high theoretical specific capacity of 3579 mAhg -1 -almost an order of magnitude higher than that of conventional graphite (372 mAhg -1 ). In addition to its high capacity, silicon is abundant, environmentally friendly, and cost-effective. However, its practical application is hindered by substantial volume expansion of up to ~300% during lithiation and delithiation, leading to structural degradation and shortened battery lifespan. Similarly, among the cathode materials, LiFePO 4 (LFP) offers several advantages such as excellent thermal stability, extended durability, and safety. It has a theoretical specific capacity of 170 mAhg -1 . Li-ion batteries with LFP cathodes have a long cycle life with excellent charging/discharging performance. However, the intrinsic low electronic conductivity and moderate ionic diffusion rate of LFP limit its rate capability and overall electrochemical performance. To overcome these challenges, surface modification strategies—particularly the application of ultrathin protective coatings—have been widely investigated. Atomic Layer Deposition (ALD) offers a powerful approach for this purpose, providing atomic-level control over film thickness and exceptional coating uniformity. The resulting ultrathin, conformal layers protect the electrode from direct electrolyte contact, suppressing parasitic side reactions and preventing the dissolution of active materials. Moreover, ALD coatings can enhance lithium-ion diffusion and reduce charge-transfer resistance, while simultaneously buffering volume changes and promoting the formation of a robust solid electrolyte interphase (SEI) layer. These combined advantages make ALD a highly effective method for improving the long-term stability and performance of lithium-ion batteries. Our work investigates the preparation, electrochemical performance, and effects of ZnO ALD coatings and electrolyte additives on silicon/graphite (Si/Gr) composite anodes, providing valuable insights into strategies for enhancing battery performance and long-term durability. [1,2] We also demonstrate that modifying the LFP cathode surface with ultrathin ALD-grown alumina films enhances Li-ion charge transfer, improves rate performance, and effectively mitigates chemical degradation. [3] Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and operando X-ray diffraction (XRD) were employed to provide detailed insights into the structural and interfacial evolution of the electrodes. We acknowledge support from VEGA 2/0135/26, M-ERA.NET SusHiBatt, APVV-24-0321 and the European Union’s Horizon Europe research and innovation program under grant agreement No. 101192848 (FULL-MAP). References [1] P. P. Sahoo, A. Güneren, B. Hudec, M. Mikolášek, A. Nada, M. Precnerová, M. Mičušík, Z. Lenčéš, P. Nádaždy, K. Fröhlich, ACS Appl. Nano Mater. 2024 , 7 , 18486. [2] P. P. Sahoo, A. Güneren, B. Hudec, M. Mičušík, P. Jr. Švec, M. Precnerová, A. Nada, Z. Lenčéš, K. Fröhlich, ACS Appl. Energy Mater. 2025 , 8 , 6925. [3] P. P. Sahoo, B. Hudec, M. Mičušík, M. Mikolášek, M. Precnerová, P. Jr. Švec, P. Nádaždy, S. Mičky, M. Zubair, P. Siffalovic, K. Fröhlich, ACS Appl. Energy Mater. 2025 , 8 , 10594.

In-rich InxAl1-xN layers were grown on sapphire substrates with an AlN nucleation layer by metal-organic chemical vapour deposition (MOCVD). Deposition parameters were varied to achieve a high In molar fraction and optimized microstructure without InAlN phase separation. Continuous flow epitaxy (CFE) and, for the first time, flow-modulated epitaxy (FME) MOCVD growth methods were applied to In-rich InAlN. Diverse micro-structural analyses were focused on the study of various crystal defects, including dislocations, significantly inclined grains, voids, and phase separation of different kinds, and were supported by electrical and optical measurements. The best structural quality was obtained by FME in 170 nm thick N-polar In0.64Al0.36N, demonstrating respective screw-and edge-type dislocations densities of 0.61 & times; 109cm-2 and 61 & times; 109cm-2, pits density of 2.4 & times; 108cm-2, surface RMS roughness of 5.3 nm, an electron density and mobility of 1.3 & times; 1019cm-3 and 37.4 cm2/Vs, respectively, and an optical band gap of 1.62 eV.

Porous Ni-Co-Cu alloys were fabricated by eliminating Zn from the as-cast precursor alloys using vapor phase dealloying method. The XRD studies point out the formation of several FCC solid solutions of TM with a small amount of ZnO. Fabricated multicomponent porous alloys have an open spongy microstructure that was formed throughout the entire depth of the precursor alloys during VPD. The results of electro catalytic activity studies using linear sweep voltammetry methods indicated that fabricated porous materials with high Ni content demonstrate better activity in both the Hydrogen evolution reaction (HER) and the Oxygen evolution reaction (OER).

The ordered tetragonal FeNi L10 phase, tetrataenite, is a promising candidate for rare earth-free permanent magnets due to its competitive magnetic properties and the low cost of the constituent elements. In this work, we have investigated the effect of molybdenum and aluminum substitution on the formation of the ordered L10 phase. The alloys were prepared with die casting and melt spinning techniques, further processed using cold rolling and cryomilling, and finally annealed below the estimated order–disorder temperature (TOD). To study the influence of composition and processing of the alloys, structural characterization and microstructural analysis were performed with synchrotron radiation X-ray diffractometry (SR-PXD) and Scanning Transmission Electron Microscopy (STEM), respectively. The presence of tetrataenite in the alloys investigated in this work could not be confirmed. In situ SR-PXD and STEM indicated minimal structural changes in the temperature stability range of the materials. A full-loop hysteresis curve acquired using a vibrating sample magnetometer (VSM) indicated no signs of magnetic hardening of the alloys with the measured coercivity being below 10 Oe, and thus consistent with FeNi without ordering.

The development of new photochromic systems is motivated by the possibility of controlling the properties and functions of materials with high spatial and temporal resolution in a reversible manner. While there are several classes of photoswitches operating in solution, the design of systems efficiently operating in the solid state remains highly challenging, mainly due to limitations related to confinement effects. Triaryl-hydrazones represent a relatively new subclass of bistable hydrazone photoswitches exhibiting efficient Z/E photochromism in solution. As "large volume" photoswitches, they have been anticipated to display only limited solid-state photoswitching. Here, we show that the Z isomers of newly prepared triaryl-hydrazones containing a perfluorinated hydrazine phenyl ring (PHZs) exhibit impressive solid-state photochromism with an unexpected light-induced red-shift of the absorption maximum. Based on (time-dependent) density functional theory calculations, a photoswitching reaction mechanism involving the excited state intramolecular proton transfer has been proposed, which rationalizes the observed red-shift in absorption by the formation of a metastable proton transfer structure. Advanced experimental techniques including X-ray diffraction, solid-state NMR and EPR spectroscopy, and confocal Raman microscopy corroborated the suggested mechanism and revealed that the observed photochromism is a superficial phenomenon. This atypical photochromic behavior of PHZs can also be realized by using visible light and in the form of thin films, which manifests their potential use in optics and optoelectronics.

Diborides of transition metals from group IVB (TMB2, TM = Ti, Zr) are desirable materials in demanding industrial conditions due to their excellent mechanical properties. Direct current magnetron sputtering (DCMS) leads to the growth of overstoichiometric (TMBx, x > 2) film with nanocomposite structure consisting of crystalline hexagonal TMB2 nanocolumns surrounded by a thin, amorphous boron-rich rich tissue phase. At elevated temperatures, the presence of the tissue phase has a negative effect on the films' mechanical properties and oxidation resistance. An innovative approach using effective ionization of sputtered species during high-power pulsed magnetron sputtering (HiPIMS) growth of ZrB2 films is presented. While layers grown using the conventional DCMS method are overstoichiometric (B/Zr = 2.2), the films grown by HiPIMS are understoichiometric, with a B/Zr ratio ranging from 1.6 to 1.9. In understoichiometric ZrB1.9 and ZrB1.6 films, detailed structural analysis using transmission electron microscopy revealed a nanocrystalline structure comprised of densely packed 10-20 nm wide nanograins. In addition, the understoichiometric films exhibit high hardness values above 42 GPa and improved high-temperature oxidation resistance compared to the ZrB2.2 film deposited by DCMS.

The experimental evidence of a large magnetoresistance in magnetite pellets is provided in this article. Applying a magnetic field along the length of the four-point resistivity probe, on the surface of a bulk magnetite pellet, results in large magnetoresistance change in the order of 150%. Measurements were realized in 10(-3) mbar vacuum with excitation currents from 0.1 A up to 0.5 A, with magnetic field from 0 mT up to 250 mT. After the exponential decrease of resistance because of the increase of the carrier number due to the temperature elevation and the semiconducting nature of the magnetite pellets, the steady-state resistance of the sample was dependent on the externally applied field. The drop of resistivity is attributed to the parallelization of the magnetic flux B of the magnetite pellet with the excitation current, thus resulting in an increase of the corresponding mean free path.

This study investigates the corrosion behaviour and underlying mechanisms of in-situ fabricated Al-AlN metal matrix composites (MMCs) produced via large-scale powder metallurgy. Two extruded composite variants containing 8.8 and 14.7 vol% AlN ( referred to as Al10AlN and Al16AlN, respectively) were tested in both transverse (T) and longitudinal (L) orientations. Corrosion performance was assessed under 100 % humid air (HA) and artificial acid rain (AR) conditions using long-term immersion testing, open-circuit potential (OCP), potentiodynamic and cyclic polarisation and electrochemical impedance spectroscopy (EIS). Post-exposure surface characterisation was performed via scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results revealed that Al-AlN MMCs exhibit overall low corrosion rates in both environments, confirming their excellent corrosion resistance. In humid air, higher AlN content was associated with increased corrosion rates while this trend was less pronounced in acidic conditions. Localised corrosion was predominantly initiated at Mg2Sn intermetallic particles, which acted as galvanic sites for pitting corrosion. Mechanical testing demonstrated that tensile properties remained largely unchanged after corrosion exposure. Anodisation markedly improved general corrosion resistance, although its effectiveness in suppressing localised attack was limited. Overall, controlling the size and distribution of Mg2Sn phases emerged as a critical strategy for enhancing corrosion performance in Al-AlN composites.

Spin control represents an interesting avenue in modern electrochemistry, with the ability to tune the state of reaction intermediates and the overall reaction selectivity and yield. One of the ways to achieve the reaction spin control is the preparation of specific electrodes through the utilization of the so-called chiral-induced spin selectivity phenomenon (CISS). This approach is based on the utilization of chiral coatings on the surface of redox-active materials, which allow one to align the spin of transited electrons, but limits the available current densities and electrode stability. In this work, the realization of the CISS phenomenon with the implementation of intrinsically chiral 2D flakes of MoS2 doped with single Ni atoms is proposed for the first time. The created material was applied to an oxygen evolution reaction (OER) performed under alkaline conditions. The singleatom catalyst provides the material redox activity, while the flakes chirality ensures the alignment of the spins of transited electrons. We reached a significant enhancement of the OER kinetics and suppressed hydrogen peroxide formation. The utilization of the proposed chiral materials allows us to perform OER experiments at a relatively high current density and significantly improve the electrode stability.

We propose a real-time, all-RRAM intelligent gas perception (RIGP) system, featuring three cross-layer innovations. At the process level, a novel direct atomic layer processing (DALP) technique eliminates lithography and etching, enabling high-quality TiO2 deposition with variable thicknesses at designated locations. At the device level, a vertical TiO2-based gas sensor, built using a standard RRAM structure, exhibits high H2 responsivity. Its self-rectifying behavior effectively suppresses sneak current paths in high-density passive arrays without transistors. At the architecture level, the RRAM gas sensor enables seamless integration with an RRAM-based in-memory computing (IMC) platform. Variable TiO2 thicknesses facilitate local feature extraction within the sensor array, eliminating the need for analog-to-digital converters (ADCs). The RIGP system, incorporating hardware-encrypted acceleration of reservoir computing (RC), achieves highly accurate real-time detection (NRMSE < 0.08) and inherent security in a compact, energy-efficient design.

In addition to its use as a lightweight material, pure magnesium is a promising candidate for prospective bioimplants considering its excellent biocompatible properties. Regardless of what Mg application is used, the ultimate goal is to improve magnesium's mechanical properties and degradation behaviour. Because of the high affinity for oxygen native oxide layer of gas-atomized powders is naturally formed in contact with the atmosphere. S/TEM investigation of the native oxide of the Mg powder particles revealed a nonhomogeneous nano-crystalline MgO layer. MgO is relatively soluble in water and does not provide sufficient corrosion protection. Among various surface treatment methods, conversion of the non-protective magnesium oxide to carbonate products is possible depending on the environmental conditions. This work used a simple experimental method using CO2 and water vapour to achieve surface carbonation of Mg powders. Two carbonated samples and pure magnesium were prepared by direct extrusion. The samples after carbonation retained good mechanical properties and the layer of carbonates had a significant impact on corrosion resistance. 1 day carbonation resulted in transformation of native oxide into amorphous layer and reduction of corrosion rate. Longer carbonation (10 days) revealed layer growth and transformation of native oxide to crystalline nesquehonite structure.

According to the well-known concept of multicomponent high-entropy alloys, high entropy of mixing can stabilize the formation of solid solutions (simple bcc or fcc crystal structure) during solidification. Stabilization of the solid solution and prevention of the formation of intermetallic phases during solidification is provided by the high entropy of mixing in the solid and liquid states. High-entropy alloys have increased strength, high hardness, thermal stability in combination with good resistance to oxidation and corrosion. These properties allow to significantly expand the scope of these alloys. In this work, the electrical resistivity, thermoelectric power and surface tension of binary Cu–Sn, Cu–Ga and Cu–Bi alloys, which are the sub-system components of model low-temperature high-entropy Bi–Cu–Ga–Pb–Sn alloys, have been studied in a wide temperature range including solid and liquid states. The lack of the surface tension data of the above-mentioned alloys is compensated by the model predicted values.

A simple, cost-effective, and environmentally friendly strategy was proposed for synthesis of three types of zeolitic imidazolate frameworks (Co, Co/Zn, and Zn based/containing) with cuboid particle morphology. The structure of (Co, Co/Zn, Zn)-ZIFs was studied by scanning electron microscopy, x-ray diffraction, and low-temperature nitrogen adsorption-desorption. To obtain information about the possibility of potential liquid-phase application of the cuboid (Co, Co/Zn, Zn)-ZIFs, hydrolytic stability testing was carried out at ambient conditions. According to the results of flame atomic absorption spectroscopy of supernatant solutions and x-ray diffraction analysis of solid samples, the negligibly small cleavage of Co-N and especially Zn-N bonds takes place during the first day of experiment with no discernible influence on the structure integrity of the studied ZIF mateials. Long-term water exposure of Co-containing ZIF materials results in transition of metal cations into the solution and noticeable transformation of crystalline structure. The effectiveness of the synthesized (Co, Co/Zn, Zn)-ZIFs in sorption of methyl orange from aqueous solutions was studied in dependence on duration of contact and equilibrium concentration of azo dye. Obtained results were analyzed by kinetic (Lagergren and Ho-McKay) and equilibrium (Langmuir, Freundlich, and Dubinin-Radushkevich) adsorption models. It was found that the kinetics of methyl orange sorption by synthesized ZIF sorbents is best described with the Ho-McKay model. The equilibrium sorption on Co-ZIF and Zn-ZIF with cuboid particle morphology proceeds in accordance with the Langmuir model, whereas interaction with heterometallic Co/Zn-ZIF agrees with the Freundlich one. The mean free adsorption energy for sorption of azo dye by ZIF materials increases in the order Zn-ZIF < Co/Zn-ZIF < Co-ZIF. The x-ray diffraction studies of (Co, Co/Zn, Zn)-ZIF materials after methyl orange sorption proved the complete transformation of mixed ZIF-L/ZIF-67 phase of cuboid Co-ZIF to rhombic dodecahedral ZIF-67.