Search Results (4,611)

The performance of coatings, corrosion barriers, photocatalysts, and tribological materials is greatly influenced by in situ surface properties, requiring highly sensitive and reproducible operando surface characterization methods. We previously developed a temperature-programmed photoelectron emission (TPPE) method to clarify electron transfer behavior on light-irradiated metal surfaces. TPPE is sensitive to surface temperature and prior chemical exposure, which affect the total photoemitted electron count (N_T), the photothreshold, and the activation energy derived from Arrhenius plots of N_T obtained during heating–cooling cycles. This study examines the reproducibility of TPPE data and the TPPE mechanisms for Cu₂O/Cu surfaces subjected to mechanical abrasion, cleaning, plasma treatment, and subsequent immersion in organic liquids. The resulting Arrhenius plots reveal both positive and negative activation energies, depending on the treatment conditions. Negative activation energies during cooling are associated with photoredox-mediated emission. TPPE is attributed to oxygen vacancies within the Cu₂O surface layer, which is interfaced with metallic Cu, serving as a direct probe of these vacancy-related states. The TPPE characteristics (N_T intensity and activation energy) following exposure to various polar and nonpolar organic molecules (e.g., acetone, toluene, hexane, and ethanol) correlate with the electronic properties of these vacancies, consistent with previous observations for ambient air, alcohol, and water vapor exposure. Under illumination, Cu₂O vacancy states enhance photocarrier extraction (electrons and holes) and accelerate surface redox reactions within adsorbed thin films, thereby improving photocatalytic performance. Notably, the solvent’s reciprocal dielectric constant significantly influences TPPE, indicative of electrostatic surface–solvent interactions. Finally, the TPPE mechanism is discussed in the context of antiviral inactivation at the metallic copper–environment interface. Full article

Magnetic molecular thin films provide a platform for nanoscale control of spin density, morphology and low-dimensional magnetism. We use co-deposition of closely isostructural iron phthalocyanine (FePc) and metal-free phthalocyanine (H₂Pc) onto heated substrates to prepare diluted thin films with systematically varied Fe spin densities. Structural and surface characterization shows that H₂Pc incorporation modifies film growth, producing a monotonic dependence of surface roughness on dilution and a grain size minimum for mixed FePc:H₂Pc films. Vibrating sample magnetometry reveals a nonlinear suppression of the magnetic response with increasing H₂Pc content, exceeding the reduction expected from FePc concentration alone. Below 5 K, the saturation magnetization is markedly reduced in diluted films compared with undiluted FePc, suggesting that molecular packing, Fe chain length and nanoscale morphology influence the magnetic coupling strength. These findings provide insight into FePc:H₂Pc co-deposition as a route to chemically tunable magnetic molecular nanomaterials and highlight the importance of structurally compatible molecular dilution for magnetic sensing applications. Full article

In this work, Cu₂CoSnS₄ (CCTS) thin films were deposited on glass substrates by thermal evaporation and investigated for photovoltaic applications. The influence of substrate temperature, varied from 25 °C to 200 °C, on the structural, morphological, and optical properties of the films was experimentally studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) measurements. XRD analysis confirmed the formation of crystalline CCTS with a stannite structure and a preferential orientation along the (112) plane. SEM observations revealed rough and non-uniform surfaces accompanied by an increase in grain size with increasing substrate temperature. Room-temperature PL measurements indicated a band-gap energy of approximately 1.3 eV, suitable for photovoltaic applications, and confirmed the presence of secondary phases in the p-type stannite CCTS films. Despite the promising photovoltaic properties of CCTS, numerical studies on CCTS-based solar cells remain scarce in the literature. In this context, a numerical study of the CCTS-based solar structure grown on glass was also performed using SCAPS-1D, showing good agreement with experimental photovoltaic results and validating the simulation model. Replacing the glass substrate with silicon improved the device efficiency to 5.77%. Further optimization of the series and shunt resistances significantly enhanced the photovoltaic performance, achieving a power conversion efficiency of 16.77%, with FF = 52.94%, V_oc = 0.89 V and J_sc = 35.19 mA/cm². Full article

We investigate the dynamic magnetic properties of an epitaxial Co₂₅Fe₇₅ thin film grown on a MgAl₂O₄ (001) substrate using broadband ferromagnetic resonance (VNA-FMR). The film exhibits a pronounced fourfold symmetry of the resonance field, characteristic of cubic magnetocrystalline anisotropy. By combining broadband and angular-dependent FMR measurements, we determined a spectroscopic g-factor of 2.083 ± 0.017, an effective magnetization of 1655 ± 31 kA/m, and a cubic magnetocrystalline anisotropy field of 28.25 ± 0.22 mT. Beyond the expected angular dependence of the resonance field, we experimentally demonstrated a pronounced flattening of the frequency versus magnetic field dependence for magnetic field direction located between the principal crystallographic axes. The effect, predicted by conventional ferromagnetic resonance theory but not previously investigated in detail, originates from the equilibrium rotation of the magnetization and is quantitatively described within the Stoner–Wohlfarth framework. For ${\varphi }_H$ = 34°, the resonance frequency remained nearly constant over the magnetic field interval from 6.8 to 26.2 mT at room temperature. A comparison with other (001)-oriented epitaxial magnetic films revealed that similar frequency plateaus can occur over frequencies ranging from 0.9 to 12.35 GHz and over magnetic field intervals from 0.5 to 63 mT. These findings establish a route toward microwave devices that are insensitive to fluctuations in the applied magnetic field and motivate further studies of spin-wave dynamics in this regime. Full article

In this paper, we have investigated the photocatalytic performances of some yttrium-doped ZrO₂ films for decomposing Rhodamine B and Methylene Blue. The as-deposited thin films (obtained by RF magnetron sputtering) were heat-treated to stabilize their structure. To assess the films’ characteristics, a group of analytical methods (XRD, XPS, AFM and DRS) allowed for the determination of their structural, surface, and optical properties. These characteristics were correlated with the observed photocatalytic activity and wetting behaviour. The Y-doped ZrO₂ film with medium nanoparticle size and a high contribution of the oxygen vacancy is found to be more efficient in Rhodamine B and Methylene Blue photodegradation; the 100% degradation efficiency was reached in 70 min and 40 min, respectively, for the 3 mg/L solution dye. The photodegradation mechanism is driven by photogenerated holes, and a possible reaction mechanism was proposed. By investigating the charge carrier separation at the film–ITO interfaces, made through a comparative analysis of their determined band edge potentials, we conclude that the transfer is not possible in either of the semiconductor pairs, so ITO does not “help” the photocatalytic process. Full article

High-entropy alloys (HEAs) are a unique metallic alloy that was initially recognized for the possibility of stabilizing simple solid-solution phases through high configurational entropy. Research over the past two decades, however, has shown that their behavior is far more complex. Phase formation, microstructural evolution, and surface performance arise from the combined influence of composition, atomic interactions, processing history, and the surrounding environment. This paper reviews the connections between these aspects moving from the bulk alloy to the surface. The thermodynamic and empirical criteria utilized for prediction of phase formation and reasons behind ignoring the factors such as ordering, segregation, metastability, and processing defects are described. Further, the influence of casting, rapid solidification, coating deposition, and thin-film processing on the microstructure that will interact with catalytic or corrosive environment is reviewed. Electrocatalysis and corrosion resistance are considered as two strongly coupled surface phenomena rather than separate fields of application. Quantitative comparison of exemplary high-entropy alloy systems shows the influence of the alloying approach and surface development on the catalytic properties, surface reconstruction, selective dissolution, passive film formation, and localized corrosion. The potential of CALPHAD modeling, density functional theory, machine learning, and multi-objective optimization for a better alloy selection in the field of high-entropy alloys is reviewed as well. We identified that the success of HEA design is not only in choosing the right composition but rather in controlling the phases, defects, interfaces, and surface of the HEA. Full article

This study developed a composite rejuvenator comprising recycled polyethylene wax (PREW), waste cooking oil (WCO), and epoxidized soybean oil (ESO) activated by the tertiary amine catalyst BDMA to improve the intermediate-temperature rejuvenation of aged SBS-modified asphalt binder. The binder was subjected to combined rolling thin-film oven and pressure aging vessel aging. Conventional tests, rotational viscosity, bending beam rheometer, multiple stress creep recovery, fluorescence microscopy, and Fourier transform infrared spectroscopy were used to evaluate macroscopic, rheological, and microstructural properties. Aging hardened and embrittled the binder, increased softening point and viscosity, reduced penetration and ductility, and disrupted the polymer-rich phase. PREW reduced flow resistance and retained relatively high-temperature structural stability, whereas WCO improved flexibility and flowability, although excessive softening impaired high-temperature stability. ESO/BDMA treatment was accompanied by changes in oxygen-containing functional group-related absorption regions and improved apparent connectivity of the SBS-rich phase. Among the tested temperatures, 120 °C provided the best overall balance among the evaluated properties, satisfying low-temperature stress-relaxation requirements while limiting high-temperature creep deformation. These results identify 120 °C as the preferred treatment temperature for the PREW/WCO/ESO-BDMA rejuvenation system. Full article

Polylactic acid (PLA) is one of the most promising bio-based and biodegradable polymers, yet its inherent brittleness limits its application in flexible film products. This study compares three mixing strategies, applied as four sample series, to improve the mechanical performance of PLA-based binary blends: (1) single-pass melt blending with poly(butylene adipate-co-terephthalate) (PBAT) or poly(butylene succinate) (PBS) at 10, 20, and 30 wt%; (2) addition of poly(ethylene glycol) (PEG 4000 or PEG 20000) as a plasticizer/compatibilizer at 1, 3, and 5 wt%; (3) double melt processing of PLA/PBAT and PLA/PBS blends. Thin films were characterised by tensile testing, differential scanning calorimetry (DSC), FTIR, SEM and contact angle measurements. Double processing emerged as the most effective approach, yielding elongation at break values up to approximately 137% for 70PLA/30PBAT blends, compared to 16.9% for the equivalent single-processed samples. Relative to the single-processed controls, double processing raised elongation at break by approximately 712% for 70PLA/30PBAT and 1201% for 70PLA/30PBS, and by 98% (80PLA/20PBAT), 175% (80PLA/20PBS) and 278% (90PLA/10PBAT); the latter three increases were statistically significant (p < 0.05). By contrast, PEG addition changed maximum stress by at most about 18% and never raised elongation at maximum stress above 6%. Two-way ANOVA confirmed that blend ratio was a significant factor for maximum stress (p < 0.001) whereas PEG molecular weight was not (p > 0.10). PEG addition produced moderate improvements in tensile stress, but did not replicate the ductility enhancement observed after reprocessing. DSC data confirmed a decrease in the glass transition temperature (Tg) and altered crystallisation behaviour in double-processed samples, consistent with improved interfacial compatibility. Contact angle results showed broadly similar surface wettability across all series, pointing to processing history, rather than surface chemistry, as the key variable governing final mechanical behaviour in these blends. Full article

This study explores the multifunctional properties of Ni nanoparticles obtained by laser ablation in liquid, with emphasis on the potential use of these nanoparticles in different applications such as cooling fluids or photoelectrochemical ones. The Ni nanoparticles were synthesized by the laser ablation in liquid technique using an Nd-YAG laser and ultrapure water as liquid. The structural, dimensional, morphologic, and stoichiometric characterizations of the nanoparticles were performed using different techniques such as transmission electron microscopy (TEM), energy dispersive X-ray (EDS) and dynamic light scattering spectroscopy (DLS). Nickel nanoparticles with sizes ranging from 5 to 15 nm in diameter were obtained. The experimental measurements were performed to determine the thermal conductivity and viscosity of the obtained nanofluids, essential parameters in the evaluation of the cooling fluid performances. Loading TiO₂ thin films with Ni nanoparticles led to the enhancement of the photoelectrochemical water splitting properties of TiO₂ thin films, the Ni nanoparticles acting on the collecting, transferring and separating the photogenerated charges and ultimately improving the overall anodic and cathodic efficiencies. The results obtained can contribute to the development of innovative, multifunctional solutions based on non-precious metals for cooling and water splitting systems used in industrial, electronics and other applications. Full article

We present a brief review that highlights the importance of III-Nitride semiconductor compounds according to their structural, compositional, morphological, and optical properties, which have significant applications in new semiconductor devices and play a fundamental role in modern electronic and optoelectronic technologies. The importance of sputtering as a viable alternative for obtaining III-Nitride semiconductor compounds is discussed. This is due to its versatility, cost, ease of handling, and advantages provided by the physics of its operation in obtaining thin films compared to techniques such as metal–organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), and molecular beam epitaxy (MBE). The physics of the sputtering method is briefly and clearly described, including magnetron configurations, plasma generation, energy dependence of sputtering, reactive sputtering, hysteresis effects, target types, and the importance of temperature and working distance between the substrate and target. In addition, the review of the literature on the application of sputtering for obtaining III-Nitride semiconductor compounds is presented. Furthermore, this review also highlights the future of sputtering, which is moving towards high-power pulsation, atomic-level precision, and AI-driven automation due to the miniaturization of electronics, advances in green technology, and innovations in plasma control to increase film density and reduce target material loss. Full article

Copper and its alloys are indispensable for electronics, communications, new energy systems, and aerospace engineering due to their exceptional electrical conductivity and mechanical properties. However, the thin cuprous oxide (Cu₂O) layer that naturally forms on copper and its alloys is prone to failure under elevated temperatures and high humidity, particularly in chloride-rich environments, leading to accelerated localized corrosion. While conventional chromate-based passivation has long been the industrial standard for preventing corrosion, its use has been increasingly restricted by global regulations (such as RoHS and REACH) due to its severe toxicity and health risks. To address the conflict between environmental compliance and protective performance, this review systematically evaluates recent advances in environmentally friendly, chromium-free anti-corrosion coatings in the present review. These alternative coatings are critically analyzed and categorized into four mechanistic groups: (i) inorganic conversion coatings (including molybdate, tungstate, rare earth, and phosphate systems); (ii) organic films formed via chemical or physical adsorption (such as organic inhibitors, thiol-based monolayers, and organosilane self-assembled films); (iii) conversion coatings engineered through covalent bonding, coordination chemistry, and microstructural tailoring; and (iv) multifunctional coatings that integrate self-healing capability with high electrical conductivity. Beyond providing a technical summary, this review explored how the swift progression of electronic information technology, new energy infrastructure, and robotics has imposed more exacting, multifunctional demands on copper components. This review provides a strategic roadmap for future research and prioritizes the creation of protection strategies that operate robustly in multi-physics coupling environments—integrating high conductivity, autonomous self-healing, and long-term chemical stability to ensure the reliability of next-generation infrastructure. Full article

We demonstrate the integration of molecular beam epitaxy (MBE)-grown InAs/InP quantum dots (QDs) on gold thin films, achieving a fivefold enhancement of telecom-wavelength emission compared with QDs grown on distributed Bragg reflectors (DBRs). Micro-photoluminescence (µ-PL) spectroscopy reveals a pronounced increase in PL intensity from the Au-integrated structures, highlighting the enhanced optical response enabled by the metallic mirror effect. Reflectivity measurements exhibit a characteristic dip near the QD emission wavelength, indicating increased optical absorption and reduced reflectance, consistent with improved coupling of incident light into the fabricated structure. Power-dependent measurements demonstrate background-free exciton and biexciton emission from single QDs with resolution-limited linewidths. Polarization-dependent measurements further reveal an ultra-small excitonic fine-structure splitting, reaching values as low as ~2 μeV. Finally, statistical analysis of multiple QDs confirms the reproducibility and robustness of the observed optical properties. Full article

The performance of low-temperature detectors utilizing thermal effects is determined by their energy relaxation properties. Usually, heat transport experiments in mesoscopic structures are carried out in the steady state, where temperature gradients do not change in time. Here, we present an experimental study of dynamic thermal relaxation in a mesoscopic system—thin metallic film. We find that thermal relaxation of hot electrons in copper and silver films is characterized by several time constants, and that the annealing of the films changes them. In most cases, two time constants are observed, and we can model the system by introducing an additional thermal reservoir coupled to the film electrons. We determine the specific heat of this reservoir and its coupling to the electrons. We suspect that multiscale thermal relaxation arises from the complicated morphology of the films, in which the electron–phonon coupling strength in grains with different orientations varies. Full article

This study presents a comprehensive investigation of the structural, morphological, and optical properties of aluminum phthalocyanine (AlPc) and silicon phthalocyanine (SiPc) thin films prepared by the close space sublimation (CSS) method, deposited at different evaporator temperatures of 350 °C, 400 °C, and 450 °C, including heterostructures incorporating an indium tin oxide (ITO) layer. Scanning electron microscopy revealed a clear temperature-dependent evolution of surface morphology, with both materials transitioning from isolated crystallites to dense, highly crystalline films. SiPc exhibited higher nucleation density and earlier film densification, while AlPc showed more pronounced grain growth at elevated temperatures, accompanied by crack formation due to internal stress. Optical absorption spectra indicated a red shift in absorption maxima with increasing deposition temperature, associated with improved crystallinity and reduced defect density. The presence of ITO significantly modified the optical response, introducing additional absorption features in the near-infrared region due to interference effects and free-carrier contributions. Fluorescence measurements revealed enhanced emission intensity with increasing temperature for AlPc, while SiPc showed weaker emission overall. The incorporation of ITO led to substantial fluorescence enhancement and the appearance of additional near-infrared emission bands, highlighting the importance of interface engineering. Transmittance spectra demonstrated that ITO-based heterostructures provide a balance between transparency and absorption, with selective attenuation in the 600–800 nm range, enabling band-stop filter behavior. Raman analysis revealed opposite temperature-dependent trends: increasing structural order in AlPc and gradual disorder in SiPc. X-ray diffraction confirmed the crystalline nature of both materials, showing temperature-induced improvements in crystallinity and crystallite size, as well as distinct differences in molecular packing and preferred orientation. These results demonstrate the potential of AlPc and SiPc thin films as functional optical materials with tunable structural and optical properties. Full article

The rapid development of implantable medical electronics requires robust biocompatible coatings capable of ensuring long-term stability in aggressive physiological environments. Although Grade 1 titanium is widely used for its excellent mechanical properties and corrosion resistance, active implants require defect-free insulating coatings to prevent electrical leakage and metal ion release. This study presents a systematic evaluation of Parylene C (P-C) thin films deposited by the Gorham chemical vapor deposition (CVD) process onto implant-grade titanium substrates. Four coating thicknesses (1, 5, 10, and 20 µm) were deposited and characterized using complementary chemical, morphological, optical, and mechanical techniques. Contact-angle measurements confirmed uniform hydrophobicity (90.56 ± 1.86°), while FTIR and EDX verified the characteristic chemical composition of P-C. Reflectometry, ellipsometry, and interferometry demonstrated excellent thickness control and deposition reproducibility. Pull-off testing showed high initial mechanical integrity, with detachment forces ranging from 52 to 73 N. However, accelerated PBS ageing (21 days at 90 °C) induced significant degradation, particularly for thicker coatings, reducing pull-off forces to 19–42 N. Likewise, thermal-shock cycling (−80 °C to +220 °C) caused severe interfacial damage, decreasing the required detachment force to approximately 5.5 N for 20 µm coatings because of extensive cracking and delamination. These results demonstrate that Parylene C provides excellent conformal coverage and chemical stability on titanium but that its durability is significantly affected by prolonged hydrothermal ageing and extreme thermal loading. This study provides practical guidelines for the design of reliable encapsulation systems for active implantable medical devices and highlights the need for improved interfacial engineering through optimized adhesion-promoting layers or hybrid protective architectures. Full article