Search Results (86)

Adjusting the Schottky barrier height is an important approach to enhancing the gas-sensing performance of TiO₂ Schottky sensors. In this study, micro TiO₂ nanotube Schottky sensors were fabricated via magnetron sputtering and anodic oxidation, with their Schottky barrier height adjusted by varying the annealing temperature. The morphology, phase composition, oxygen vacancy concentration, band structure, and Schottky junction of the samples were investigated using SEM, GIXRD, EPR, Hall effect measurements, XPS, I-V curves, and AC impedance. The sensor annealed at 500 °C demonstrated the highest gas-sensing response, outperforming sensors treated at other temperatures by over 100 times. Its response value to 1 ppm H₂ was 242. The annealing temperature significantly affects the TiO₂ phase and oxygen vacancy concentration, resulting in the highest Schottky barrier height in the 500 °C-annealed sensor, which contributes to its superior sensing performance. AC impedance measurements revealed no significant Fermi-level pinning in TiO₂. Based on the gas-sensing mechanism analysis, the response of the TiO₂ sensor can be divided into three regimes: Schottky junction control, TiO₂ resistance control, and co-control. Full article

This work presents a study on the evaluation of the erosive wear behavior of laminated composites, manufactured using the vacuum-assisted resin infusion (VARI) method with a glass fiber-reinforced epoxy matrix modified with SiO₂ nanoparticles (0.0, 1.5, and 3.0 wt.%). Results indicate that nanoparticle concentration and dispersion state critically influence the mechanical and tribological performance. The composite FG-1.5-SiO₂ with 1.5 wt.% SiO₂ exhibited optimal nanoparticle distribution, as confirmed by FTIR, GIXRD, and SEM analyses, with the lowest surface roughness (Ra = 0.215 μm), highest hardness (35.58 HV), and highest elastic modulus (19.66 GPa). These enhancements contributed to a 38% improvement in erosion rate compared to the unmodified laminated composite, with the lowest total mass loss (0.0261 mg) and erosion rate (2.3360 × 10⁻⁵ mg/g). Profilometry and SEM results revealed shallower wear depths and reduced matrix removal, indicating stronger fiber–matrix interface integrity. In contrast, the 3.0 wt.% SiO₂ composite (FG-3-SiO₂) suffered from nanoparticle agglomeration, which increased surface roughness, diminished mechanical properties, and reduced erosion resistance to levels comparable to the unreinforced material. The results indicate that homogeneous dispersion at an optimal concentration (1.5 wt.%) is crucial for improving erosion resistance, while agglomeration at higher concentrations negates the potential benefits of nanoparticle incorporation. These findings highlight the need to optimize nanoparticle dispersion for the development of fiberglass/epoxy composites with greater durability and erosion resistance in demanding applications. Full article

This study investigates the effects of deposition angle and arc current on the surface morphology and optical response of Ti coatings obtained by unfiltered cathodic arc evaporation for spectrally selective solar-thermal applications. 100 nm-thick Ti films were deposited at normal (0°) and oblique (80°) angles of incidence, with arc currents of 65 A and 90 A, respectively. The SEM measurements revealed the characteristic arc-generated microdroplet population. At normal incidence (0°), droplets are predominantly spherical and relatively uniformly distributed, whereas at 80° incidence, many droplets exhibit elongated footprints aligned with the incoming flux from the Ti cathode. This behavior is consistent with oblique-angle deposition (OAD), where the arrival geometry can promote self-shadowing and transient droplet spreading before solidification. AFM confirms an increase in nanoscale roughness, whereas GIXRD indicates nanocrystalline α-Ti and cubic TiO, with maximum crystallinity for 0°/65 A. Contact-angle measurements demonstrate a transition from hydrophobic 316L (~103°) to moderately hydrophilic Ti-coated surfaces (~68–72°), with only minor dependence on deposition geometry. Optical reflectance in the 400–800 nm range is significantly lower for Ti-coated glass and is further reduced for OAD films, indicating enhanced solar absorptance. Full article

This study employed a combined electrochemical-Raman and synchrotron GIXRD-electrochemical approach to characterize the passive film growth on Fe-30Cr in situ. During passivation, adsorbed species such as (Cr,Fe)-OH ads and FeOOH evolved into stable oxides (Cr₂O₃, Fe₂O₃, FeCr₂O₄), forming a dense, protective layer. The results provide direct evidence of the passivation mechanism of Cr-containing alloys in marine environments and offer insights into the structural evolution and corrosion resistance of passive films. Full article

Ferroelectricity in hafnium oxide (HfO₂)-based thin films has emerged as a scalable pathway toward CMOS-compatible non-volatile memories and logic devices. This study examines how dopant chemistry and film thickness influence the stabilization of the ferroelectric phase in ALD-grown HfO₂ thin films doped with Zr, Al, and Y. Structural, morphological, and electrical characterizations were carried out using AFM, GIXRD, P–E, in-plane I/W–E, and C–V measurements on films with thicknesses of 7 nm and 100 nm. AFM revealed atomically smooth and dense surfaces (R_q < 0.5 nm), while GIXRD confirmed the stabilization of the orthorhombic Pca2₁ phase in doped 7 nm films and its relaxation toward the monoclinic phase at 100 nm. The 7 nm HfZrO and HfYO films exhibited robust ferroelectric hysteresis with remanent polarization values up to 60 μC·cm⁻², whereas HfAlO showed a narrower but still distinct switching response. In-plane I/W–E characteristics indicated a combination of Poole–Frenkel and injection-limited conduction, consistent with defect-assisted polarization reversal and asymmetric contact barriers. At 100 nm, all films showed reduced polarization and partially dielectric behavior, as corroborated by the C–V data. These results demonstrate that nanoscale confinement, dopant-induced strain, and oxygen vacancy related defect chemistry collectively stabilize the orthorhombic ferroelectric phase, with Zr doping providing the most favorable balance between polarization strength and leakage control. Full article

The spontaneous formation and stability of a protective passive film on a metal surface are crucial for the metal material’s corrosion resistance during its service life. Passive films have been extensively studied, and our understanding of passive films has been significantly improved with the development of advanced analytical techniques. Modern synchrotron X-ray sources offer unprecedented possibilities for detailed analyses of passive films and for in situ and operando studies of passive films in both gaseous/aqueous environments, as well as in electrochemical environments. This mini review presents a short summary of recent studies on passive films, mainly focusing on stainless steels and nickel-base alloys, which utilize state-of-the-art synchrotron X-ray techniques, particularly X-ray photoelectron spectroscopy (XPS), often in combination with other synchrotron techniques such as X-ray adsorption, diffraction, reflectivity, and fluorescence. These reports demonstrate that synchrotron-based techniques greatly improve probing sensitivity and spatial resolution, enabling in situ and operando studies of passive films at solid–liquid interfaces. These studies reveal changes in the passive film and underlying alloy layer, highlighting the important role of hydroxides, as well as the inhomogeneity in passive films associated with the complex microstructures in advanced industrial alloys. Full article

As 3D stacking technologies advance, low-temperature hybrid Cu bonding has become essential for fine-pitch integration. This study focuses on evaluating Pd nanolayers deposited by electroless plating (ELP) on Cu surfaces and compares them to electroplated (EP) Pd to assess their suitability for hybrid bonding. Pd nanolayers (5~7 nm) were deposited on Cu films, and their surface morphology, crystallinity, and chemical composition were characterized using AFM, TEM, GIXRD, and XPS. EP-Pd layers exhibited lower roughness and larger grain size, acting as effective Cu diffusion barriers. In contrast, ELP-Pd layers showed small grains, higher surface roughness, and partial Cu diffusion and oxidation. At 200 °C, both Pd layers enabled bonding, but ELP-Pd samples achieved more uniform and continuous interfaces with thinner copper oxide layers. Shear testing revealed that ELP-Pd samples exhibited higher average bonding strength (20.58 MPa) and lower variability compared to EP-Pd (16.47 MPa). The improved bonding performance of ELP-Pd is attributed to its grain-boundary-driven diffusion and uniform interface formation. These findings highlight the potential of electroless Pd as a passivation layer for low-temperature hybrid Cu bonding and underscore the importance of optimizing pre-bonding surface treatments for improved bonding quality. Full article

This parameter study examines the impact of two distinct adhesion layers, chromium (Cr) and titanium (Ti), on the performance of CuO/Cu₂O-based chemoresistive gas sensors by varying the layer thickness. The sensing material utilised on a Si-SiO₂ sensor chip with Pt electrodes is an ultrathin CuO/Cu₂O film fabricated through thermal deposition of Cu and subsequent oxidation. The sensors were evaluated by measuring the change in electrical resistance against a range of target gases, including carbon monoxide (CO), carbon dioxide (CO₂) and a mixture of hydrocarbons (HC_Mix), in order to assess any potential cross-sensitivity issues. As the reactions occur at the surface, the surface was characterised by scanning electron microscopy (SEM) and the composition by grazing incidence X-Ray diffraction (GIXRD) measurement to gain further insight into the influence of the adhesion layer on the sensing performance. Full article

In this paper, the oxidation behavior of the 310H alloy coated with NiCrAlY using the EB-PVD method is studied after exposure to water at a high temperature and pressure (550 °C and 25 MPa) for different periods (720 h, 1440 h, and 2160 h). The Electron Beam Physical Vapor Deposition (EB-PVD) method was used to obtain the NiCrAlY coating. After testing, the coating performance was carried out by gravimetric analysis, grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and the linear polarization method. GIXRD analysis highlighted the presence of chromium oxide (Cr₂O₃) and the Corundum phase (Al₂O₃) on the surface of the oxidized NiCrAlY-coated 310H samples. On the surface of the 310H alloy, the existence of the NiCrAlY coating and of the oxide film generated during oxidation are evident according to the EIS spectra, which show two capacitive semicircles in the Nyquist diagram. Furthermore, an increase in diameter semicircles with the oxidation time increasing was observed in the Nyquist diagram. Very low corrosion rates of 4.8 × 10⁻⁵ mm × year⁻¹, which were observed for oxidization for 2160 h NiCrAlY-coated samples, indicated that the oxide films are more protective and provide better corrosion resistance, which is also evidenced by the EIS analysis. Considering the obtained results, a significant relationship between the electrochemical technique, scanning electron microscopy, and gravimetric analysis was established. Full article

To improve the friction performance and service life of protective coatings in humidity-fluctuating environments, porous hard titanium nitride (TiN)–molybdenum disulfide (MoS₂) composite coatings were prepared by using direct current magnetron sputtering (DCMS) with the mode of oblique angle deposition (OAD) and chemical vapor deposition (CVD) technologies. The structure and chemical component were characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), grazing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The tribological properties of these TiN–MoS₂ composite coatings were investigated. The results indicate that the porous TiN–MoS₂ composite coating exhibited outstanding friction performance and long service life under humidity-fluctuating environments. At the initial 20% relative humidity (RH) stage, the MoS₂ on the porous TiN–MoS₂ composite coating surface worked as an effective lubricant; thus, the coating demonstrated excellent lubrication performance, and the friction coefficient (COF) was about 0.05. As the humidity was alternated to 70% RH, the lubrication effect diminished due to the production of molybdenum oxide (MoO₃), and the COF was about 0.2, which was attributed to the degradation of MoS₂ on the wear track and the release of fresh MoS₂ from the porous TiN matrix. After the environmental conditions shifted from 70% to 20% RH, the MoO₃ was removed, and the lubrication effect was restored. In summary, TiN–MoS₂ porous composite coating offers a promising approach for lubrication in humidity-fluctuating environments. Full article

Bacterial cellulose (BC) has earned a well-defined place among biopolymers due to its unique physicochemical properties. Unfortunately, native BC lacks antimicrobial and antioxidant properties. To address this limitation, many BC-based nanocomposites with antimicrobial properties have been developed, primarily for applications in the biomedical field, but also for use in food packaging. Many nanoparticles can be incorporated into BC membranes, often in combination with other bioactive molecules. Among the available methods for nanoparticle synthesis, green synthesis has emerged as promising, as it avoids the use of hazardous chemicals. The aim of this paper is to develop and characterize antimicrobial composite materials fabricated using carboxymethyl cellulose (CMC) and bacterial cellulose fibrils loaded with zinc oxide and silver nanoparticles (NPs) obtained using turmeric extract by green synthesis. NP-loaded CMC-BC composites were characterized using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, Grazing incidence X-ray diffraction (GI-XRD), and thermal analysis (TA). The antibacterial potential of such composites was tested against Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), and Candida albicans (C. albicans). Full article

This work studied the effect of sequential irradiation by krypton and helium ions at room temperature on the composition and structure of CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs). Irradiation of the HEAs by 280 keV Kr¹⁴⁺ ions up to a fluence of 5 × 10¹⁵ cm^–2 and 40 keV He²⁺ ions up to a fluence of 2 × 10¹⁷ cm^–2 did not alter their elemental distribution and constituent phases. Blisters formed on the nickel surface after sequential irradiation, where large blisters had an average diameter of 3.8 μm. The lattice parameter of the (Co, Cr, Fe and Ni) and (Co, Cr, Fe, Mn and Ni) solid solutions increased by 0.17% and 0.37% after sequential irradiation, respectively. Irradiation by Kr ions led to a decrease in tensile macrostresses in the HEAs in the region of krypton ion implantation (Region I) and the formation of compressive macrostresses in the region behind the peak of implanted krypton (Region II). Sequential irradiation formed large compressive stresses in Ni and HEAs equal to −131.5 MPa, −300 MPa and −613.5 MPa in Ni, CoCrFeNi and CoCrFeMnNi, respectively, in the Region II. Irradiation by krypton ions decreased the dislocation density by 1.6–2.3 times, and irradiation with helium ions increased it by 11–15 times relative to unirradiated samples for CoCrFeNi and CoCrFeMnNi, respectively. Sequentially irradiated CoCrFeMnNi HEA had higher macrostresses and dislocation density than CoCrFeNi. Full article

This study aims to improve the photocatalytic properties of titanium dioxide nanorods (TNRs) and other related nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) by modifying them with silver nanoparticles (AgNPs). This preparation is carried out using a two-step method: sol–gel dip-coating deposition combined with hydrothermal crystal growth. Further modification with AgNPs was achieved through the photoreduction of Ag⁺ ions under UV illumination. The investigation explores the impact of different growth factors on the morphological development of TiO₂ nanostructures by modulating (i) the chemical composition, the water:acid ratio, (ii) the precursor concentration involved in the hydrothermal process, and (iii) the duration of the hydrothermal reaction. Morphological characteristics, including the length, diameter, and nanorod density of the nanostructures, were analyzed using scanning electron microscope (SEM). The chemical states were determined through use of the X-ray photoelectron spectroscopy (XPS) technique, while phase composition and crystalline structure analysis was performed using the Grazing Incidence X-ray Diffraction (GIXRD) method. The results indicate that various nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) can be obtained by modifying these parameters. The photocatalytic efficiency of these nanostructures and Ag-coated nanostructures was assessed by measuring the degradation of the organic dye rhodamine B (RhB) under both ultraviolet (UV) irradiation and visible light. The results clearly show that UV light causes the RhB solution to lose its color, whereas under visible light RhB changes into rhodamine 110, indicating a successful photocatalytic transformation. The nanoball-like structures’ modification with the active metal silver (TNRs 4 Ag) exhibited high photocatalytic efficiency under both ultraviolet (UV) and visible light for different chemical composition parameters. The nanorod structure (TNRs 2 Ag) is more efficient under UV, but under visible-light photocatalyst, the TNRs 6 Ag (dense nanorods) sample is more effective. Full article

Solution-based inorganic–organic halide perovskites are of great interest to researchers because of their unique optoelectronic properties and easy processing. However, polycrystalline perovskite films often show inhomogeneity due to residual strain induced during the film’s post-processing phase. In turn, these strains can impact both their stability and performance. An exhaustive study of residual strains can provide a better understanding and control of how they affect the performance and stability of perovskite films. In this work, we explore this complex interrelationship between residual strains and electrical properties for methylammonium ${\mathrm{CH}}_3{\mathrm{NH}}_3{\mathrm{PbI}}_{3-\mathrm{x}}{\mathrm{Cl}}_{\mathrm{x}}$ films using grazing incidence X-ray diffraction (GIXRD). We correlate their resistivity and carrier mobility using the Hall effect. The ${\sin }^2\left(\psi \right)$ technique is used to optimize the annealing parameters for the perovskite films. We also establish that temperature-induced relaxation can yield a significant enhancement of the charge carrier transports in perovskite films. Finally, we also use Raman micro-spectroscopy to assess the degradation of perovskite films as a function of their residual strains. Full article

Monolayers of Ti and TiN coatings, as well as a Ti/TiN bilayer coating, were deposited on AISI M2 steel substrates using the PVD cathodic arc technique. The coatings had a thickness close to 5 μm and an average roughness between 98.6 and 110.1 μm due to the presence of microdroplets on the surface. The crystalline structure of the materials was analyzed using Grazing Incidence X-ray Diffraction (GIXRD) with an increase in temperature to study the dynamics of oxide formation. A phase composition study was conducted using the Rietveld refinement method. At the temperatures where critical growth of titanium oxides, both anatase and rutile, was observed, pin-on-disk tests were performed to study the tribological properties of the materials at high temperatures. It was determined that the oxidation temperature of Ti is around 450 °C, promoting the formation of a combination of anatase and rutile. However, the formation of rutile inhibits the formation of anatase, which is stable above 600 °C. In contrast, TiN showed an oxidation temperature of 550 °C, with an exclusive growth of the rutile phase. The Ti/TiN bilayer exhibited mixed behavior, with the initial growth of anatase promoted by Ti, followed by the formation of rutile. Oxidation and tribo-oxidation dominated the wear behavior of the surfaces, showing a transition from mechanisms related to abrasion at low and medium temperatures to a combination of abrasion and adhesion mechanisms at high temperatures (800 °C). Full article