Changes In Film Structure Research Articles

Polyhydroxykanoate-Assisted Photocatalytic TiO2 Films for Hydrogen Production.

The photocatalytic production of hydrogen using biopolymer-immobilized titanium dioxide (TiO2) is an innovative and sustainable approach to renewable energy generation. TiO2, a well-known photocatalyst, benefits from immobilization on biopolymers due to its environmental friendliness, abundance, and biodegradability. In another way, to boost the efficiency of TiO2, its surface properties can be modified by incorporating co-catalysts like platinum (Pt) to improve charge separation. In this work, the surface of commercial TiO2 PC500 was modified with Pt nanoparticles (Pt1%@PC500) and then immobilized on glass surfaces using polyhydroxyalkanoate biopolymer poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBH). The as-prepared immobilized Pt-modified TiO2 photocatalysts were fully characterized using various physicochemical techniques. The photocatalytic activity of the photocatalyst film was investigated for photocatalytic hydrogen production through water reduction using ethanol as a sacrificial donor. The impact of the film preparation conditions, e.g., PHBH concentration, PHBH:catalyst ratio, and temperature, on activity and stability was studied in detail. The application of biopolymer PHBH as a binder provides a green alternative to conventional immobilization methods, and with the application of PHBH, a stable and active photocatalyst film that showed lower activity compared to that of the suspended photocatalyst but good recyclability in six runs was prepared. A long-term photocatalytic hydrogen production experiment was carried out. In 98 h of operation, 12 mmol of hydrogen was produced in three consecutive runs with a PHBH/Pt1%@PC500 film having an area of ∼5.3 cm2. A significantly lower hydrogen productivity was observed after the first run, possibly due to a change in film structure, but thereafter, the productivity remained almost constant for the second and third runs. Hydrogen was the main product in the gas phase (90%), but carbon dioxide (4-5%) and methane (4-5%) were obtained as important byproducts. The byproducts are a consequence of the use of the sacrificial reagent ethanol. The results of the film performance are very promising, with regard to large-scale continuous hydrogen production.

Influence of Ta2O5 nanoparticles on the polyvinyl alcohol films’ structure and optical parameters for UV shielding applications

Our current objective is to develop a pioneering system utilizing polyvinyl alcohol (PVA) as a host matrix for the Ta2O5 nanoparticles for shielding applications. The PVA-Ta2O5 films were obtained via casting and characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and a polarized optical microscope. XRD and FTIR analyses showed the incorporation of Ta2O5 nanoparticles in the PVA matrix and the change in the polymeric film structure. The optical bandgap energy of the PVA was affected by the inclusion of Ta2O5 nanoparticles and was investigated through Tauc's relation using the absorption data recorded from the ultraviolet–visible spectrophotometer. The direct/indirect bandgaps decreased from 5.37/4.51 eV to 3.52/2.24 eV for PVA undoped and PVA after doping with 5.7 % Ta2O5, respectively. Moreover, the refractive index of the polymer film increased from 1.9148 for pure PVA to 2.3347 after 5 % Ta2O5 was added to the PVA. Adding Ta2O5 nanoparticles to the PVA film improves PVA's optical parameters, qualifying it for use in many optical applications.

Impact of surface topography and hydrophobicity in varied precursor concentrations of tenorite (CuO) films: a study of film properties and photocatalytic efficiency

Semiconductor films are crucial in photocatalysis applications, yet their controlled production remains challenging. Previous studies have mainly focused on deposition processes, heating rates, and doping of semiconductor oxides. In this paper, we introduce a novel method for fabricating tenorite (CuO) semiconductor films with varying precursor concentrations (0.01, 0.02, 0.04, 0.06, and 0.1 g/ml) using a dip-coating technique. We explore the impact of contact angles, 3D surface topography, and film thickness on photoactivation properties, areas with limited previous research focus. The results demonstrate that higher-concentration tenorite films (0.1 g/ml) exhibit rougher surfaces (77.3 nm), increased hydrophobicity (65.61°), improved light-harvesting ability, enhanced charge separation, and higher active oxygen output. The crystal sizes were within the range of 7.3–44.1 nm. Wettability tests show a 21.47% improvement in the 0.1 g/ml film surface under indirect sunlight compared to darkness. Transmittance rates in the 600 nm range were from 0.02 to 90.94%. The direct optical band gaps were 1.21–2.74 eV, while the indirect band gaps remained unaffected (0.9–1.11 eV). Surface morphology analysis reveals an increased presence of grains with higher concentrations. Regarding photocatalysis's impact on film morphology and copper content, SEM images reveal minimal changes in film structure, while copper content remains stable with slight variations. This suggests strong adhesion of tenorite to the film after photocatalysis. Tenorite thin films display exceptional photocatalytic efficiency, making them suitable for practical applications.

In situ temperature synthesis and characterization of ferroelectric PZN-4.5PT nanoparticles’ thin films using synchrotron light source

ABSTRACT Despite the excellent properties of Pb(Zn1/3Nb2/3)O3-4.5PbTiO3 (PZN-4.5PT) single crystals, the greatest difficulty for their application on electronic devices is to make them to thin layers related to the difficulty to make them as ceramic materials. In this paper, we use the combined USAXS/SAXS/WAXS instrument at 9ID beamline at APS-ANL for in situ characterization of PZN-4.5PT inorganic perovskite nanoparticles thin films deposited on nanotextured silicon to understand the phase transitions and determine the observed microcrystals' structure. The sample was annealed from ambient to 1000°C. The results revealed structure changes in the nanoparticles' thin films which could be explained by the new phase that can be assigned to the Pb3(PO4)2-based component. The peak at 31° indicates the presence of the rhombohedral phase perovskites assigned to the nanoparticles. WAXS characterization permitted to identification of many transitions during thermal annealing like dehydration or dihydroxylation of phosphorus gel –OH bonds and internal water.

Advanced Characterization Methodology to Unravel the Biodegradability of Metal-Organic Framework Nanoparticles in Extremely Diluted Conditions.

Porous iron(III) carboxylate metal-organic frameworks (MIL-100; MIL stands for Material of Institute Lavoisier) of submicronic size (nanoMOFs) have attracted a growing interest in the field of drug delivery due to their high drug payloads, excellent entrapment efficiencies, biodegradable character, and poor toxicity. However, only a few studies have dealt with the nanoMOF degradation mechanism, which is key to their biological applications. Complementary methods have been used here to investigate the degradation mechanism of Fe-based nanoMOFs under neutral or acidic conditions and in the presence of albumin. High-resolution STEM-HAADF coupled with energy-dispersive X-ray spectroscopy enabled the monitoring of the crystalline organization and elemental distribution during degradation. NanoMOFs were also deposited onto silicon substrates by dip-coating, forming stable thin films of high optical quality. The mean film thickness and structural changes were further monitored by IR ellipsometry, approaching the "sink conditions" occurring in vivo. This approach is essential for the successful design of biocompatible nano-vectors under extreme diluted conditions. It was revealed that while the presence of a protein coating layer did not impede the degradation process, the pH of the medium in contact with the nanoMOFs played a major role. The degradation of nanoMOFs occurred to a larger extent under neutral conditions, rapidly and homogeneously within the crystalline matrices, and was associated with the departure of their constitutive organic ligand. Remarkably, the nanoMOFs' particles maintained their global morphology during degradation.

Unveiling the Anomalous Hall Response of the Magnetic Structure Changes in the Epitaxial MnBi2Te4 Films.

Recently discovered as an intrinsic antiferromagnetic topological insulator, MnBi2Te4 has attracted tremendous research interest, as it provides an ideal platform to explore the interplay between topological and magnetic orders. MnBi2Te4 displays distinct exotic topological phases that are inextricably linked to the different magnetic structures of the material. In this study, we conducted electrical transport measurements and systematically investigated the anomalous Hall response of epitaxial MnBi2Te4 films when subjected to an external magnetic field sweep, revealing the different magnetic structures stemming from the interplay of applied fields and the material's intrinsic antiferromagnetic (AFM) ordering. Our results demonstrate that the nonsquare anomalous Hall loop is a consequence of the distinct reversal processes within individual septuple layers. These findings shed light on the intricate magnetic structures in MnBi2Te4 and related materials, offering insights into understanding their transport properties and facilitating the implementation of AFM topological electronics.

Reactive remote plasma sputtering of TiOx thin films and controlled growth of textured single-phase rutile using rf substrate biasing

Titanium oxide (TiOx) thin films were deposited by remote plasma sputtering (RPS) with the use of rf substrate bias onto unheated and water-cooled glass, Si, and Kapton substrates. The rf remote plasma power was kept constant (2.0 kW) and the properties of the films were studied as a function of deposition rate and substrate bias voltage. Four different reactive processes at four different deposition rates were developed under zero bias conditions by altering the target bias voltage and the flow of oxygen to give highly transparent TiOx films. These processes were studied with varying substrate bias voltage and the film structural, optical, and surface properties were investigated by GI-XRD, SEM, transmission, and sessile drop measurements. The changes in film structure and properties observed were related to the plasma conditions of the RPS system, investigated by dc electrical probe and OES measurements, and compared with other observations for films deposited under energetic conditions in the literature. All films deposited under zero bias conditions exhibited amorphous structures in GI-XRD and SEM images. Sufficient application of substrate bias was seen to promote columnar growth in cross-sectional SEM images and to crystallise phase pure rutile with no detection of the anatase phase in GI-XRD. Rutile bearing films were noted for their change in optical properties. Further increase of the substrate bias voltage caused a change in the texture of the rutile films from a low-energy [110] preferred orientation to a high-energy [101] and [002] preferred orientation. Contact angles of water with deposited films were found to increase with increasing substrate bias voltage and decreasing deposition rate. Film stress was also found to be influenced mainly by the substrate bias voltage process parameter.

In-situ photocatalytic degradation of low-density polyethylene: A pathway towards eco-sustainability and circular economy

The present study demonstrates the accelerated rate of photo-degradation in low-density polyethylene (LDPE) films using nanomaterials like titanium dioxide (TiO2) in a photochemical reactor, an efficient, environmentally benign, and sustainable chemical. The effect of various parameters such as source of light, catalyst loading, pH, and temperature was investigated to achieve maximum degradation on a laboratory scale. The surface morphology with molecular and chemical structure changes in the nanocomposite films was monitored before and after degradation using various analytical techniques. It is found that the degradation reaction rate is greatly affected by pH and temperature and follows the first-order photo-thermal kinetics reactions. The calculated activation energies for the different properties range from 77.6 kJ/mol for carbonyl group formation to 55 kJ/mol for vinyl group formation at an optimum pH of 4 and temperature of 30 °C, respectively. The optimized sample's storage modulus (Esm) increased from 17.76 to 210 MPa, demonstrating the loss of tensile strength after irradiation and increased elasticity. Thus, it clearly demonstrated that the LDPE sample loaded with 12% catalyst and exposed to 288 h at pH 4 and 30 °C temperature degraded most efficiently with 6.25% weight loss. In addition, there is a high correlation between the area of degradation and carbonyl index with R2 > 0.96, which helps in validating the fact that during the degradation process, there is volatilization of degradation products that leads to the formation of 0.523 mm (in length) of holes (microscopic analysis). This study brings new insights into reducing plastic pollution by minimizing waste prevention and generation at the source by promoting the usage of intermediates (formed during degradation) as a secondary material for producing new plastic products.

Corundum-structured AlCrNbTi oxide film grown using high-energy early-arriving ion irradiation in high-power impulse magnetron sputtering

Multicomponent or high-entropy oxide films are of interest due to their remarkable structure and properties. Here, energetic ion irradiation is utilized for controlling the phase formation and structure of AlCrNbTi oxide at growth temperature of 500°C. The ion acceleration is achieved by using a high-power impulse magnetron sputtering (HiPIMS) discharge, accompanied by a 10 μs-long synchronized substrate bias (Usync), to minimize the surface charging effect and accelerate early-arriving ions, mainly Al+, O+, Ar2+, and Al2+. By increasing the magnitude of Usync from −100 V to −500 V, the film structure changes from amorphous to single-phase corundum, followed by the formation of high-number-density stacking faults (or nanotwins) at Usync = −500 V. This approach paves the way to tailor the high-temperature-phase and defect formation of oxide films at low growth temperature, with prospects for use in protective-coating and dielectric applications.

Degradation characteristics of polybutylene adipate terephthalic acid (PBAT) and its effect on soil physicochemical properties: A comparative study with several polyethylene (PE) mulch films

The degradation process of different types of mulch in agriculture and its effect on soil ecosystem should be considered comprehensively. To this end, the changes in performance, structure, morphology, and composition of PBAT film during the degradation process were examined through a multiscale approach in comparison with several PE films and their effects on the soil physicochemical properties were investigated. At the macroscopic scale, the load and elongation of all films decreased with increasing ages and depths. At the microscopic scale, the stretching vibration peak intensity (SVPI) for PBAT and PE films decreased by 48.8 ∼ 60.2% and 9.3 ∼ 38.6%, respectively. The crystallinity index (CI) increased by 67.3 ∼ 209.6% and 15.6 ∼ 21.8%, respectively. At the molecules scale, terephthalic acid (TPA) was detected in localized soil with PBAT mulch after 180 d. In short, the degradation characteristics of PE films were depended on their thickness and density. The PBAT film exhibited the highest degree of degradation. Simultaneously, the soil physicochemical properties such as soil aggregates, microbial biomass and pH were affected by the changes of film structure and components during the degradation process. This work has practical implications for the sustainable development of agriculture.

Electrochemical behavior of oxazoline‐based plasma polymers for biosensing applications

AbstractPlasma‐polymerized polyoxazoline (POx) thin films offer a fast, scalable, and solvent‐free method of electrode functionalization through the unique chemistry of the oxazoline ring. However, for POx to be a viable green alternative to existing surface modification approaches, the films should be able to withstand the processing steps involved in biosensing. Here, the effects that current exposure, extended incubation, and repeated electrode rinses have on the electrochemical and physical stability of polymethyloxazoline thin films are investigated. The films are observed to become more diffusive after incubation and rinse steps. While no significant changes in chemistry were observed, a marked change in nanotopography occurred after exposure to current, suggesting a change in the polymer film structure.

The interface effects on the breakdown strength of multilayer PVDF-based capacitors

Exploring polymer-based films with high energy density and low cost is important, because they have potential applications in flexible electronic equipment. In this paper, we investigated the evidence of structure changes in multilayer films and elaborated on the part of interface effects on dielectric properties. Polyvinylidene fluoride (PVDF) and poly (vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) were spun-coated to form multilayer polymer films. The PVDF/P(VDF-HFP)/PVDF multilayer film has an improved breakdown strength of 4492 kV cm−1 and a discharged energy density of 6.24 J cm−3. According to experimental results, an increase in breakdown strength is caused by an improvement in leakage current and a reduction in ferroelectric β-phase. The high breakdown strength of multilayer films contributes to the improvement of energy storage density. This work will provide a process method for creating low cost, defect-free, high energy density polymer capacitors.

Microscopic studies on transparent AlSiN ternary hard coating

In this work AlSi nanocomposite coating were deposited by RF magnetron sputtering in Ar/N2 reactive atmosphere. AlSi alloy target of composition 86:14 wt % have been used to deposit the coating on float glass substrate by varying the deposition time: starting from 0.5 h to 2 h. The substrate temperature and target power were fixed at 250 °C and 100 W respectively. The effect of deposition time on microstructure, mechanical and optical property were studied by usingX-ray Diffraction (XRD), Stylus profiler, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), UV–Visible Spectrometer and Nanoindentation techniques. The XRD shows the formation h-AlN phase for film deposited for 2 h which shows that with increase in deposition time, the film structure changes from amorphous to polycrystalline, the coating deposited for 2 h develops wurtzite-AlN nanocrystalline structure. The thickness of the coating increases with respect to the increasing deposition time which was confirmed from stylus profiler. The FESEM study shows the uneven and randomly oriented grains present in the coating. TEM study confirms the amorphous and polycrystalline nature of the films with low and high thickness respectively. The elemental composition was confirmed by EDS. UV–Visible Spectrometer delivers the optical transparency of the film which is >90% for all the coatings in the visible range spectra. The roughness of the samples was also measured from scanning probe microscope image, which showed average roughness (Rã) value below 2 nm. The maximum hardness obtained is 31 GPa for the coating deposited 2 h with 490 nm thickness, it has an elastic recovery of 92% which suggest its resistance to elasticity as well as plastic deformation.

Плёнки FeZrN: статические и СВЧ магнитные свойства

The phase-structural state, magnetic structure parameters, static and microwave magnetic properties of Fe81 – 74Zr2 – 5N17 – 21 films prepared by reactive magnetron deposition were studied. As the Zr and N contents increase, the film structure changes from, so-called, mixed structure (grain size 3 – 6 nm of nanocrystalline α-Fe(Zr,N) + fcc nitride) to amorphous one. The film magnetic structure parameters (effective anisotropy field of stochastic domains D1/2〈Ha〉 = 11.8 ± 8 Oe and effective local anisotropy field D1/2Ha = 880 ± 700 Oe), saturation magnetization Ms (1.8 ± 0.3 T), coercive field Hc (11 ± 2 Oe), and the real permeability µ′ (80 ± 30), retaining its value at frequencies up to 3 GHz, were determined. The values of the initial permeability µ0 (70 ± 21) obtained from the hysteresis and the real permeability µ′ (80 ± 30) obtained from microwave measurements are in good agreement. The correlation between the static magnetic properties, the stochastic magnetic structure parameters and the real permeability µ′ was considered. There is no any sign on ferromagnetic resonance in the studied frequency range. However the Acher’s coefficient value (less than 0.38) for this frequency range indicates the possibility of ferromagnetic resonance at higher frequencies.

Change of the elastic strain in SiC films growing on Si substrates by the method of consistent atomic substitution

Sequential stages of synthesis of SiC epitaxial films on n- and p-type Si(111) substrates in a mixture of carbon monoxide and silane are studied by X-ray diffraction (XRD) and Raman scattering methods. It was found that the elastic strain in SiC films grown on n-type Si(111) is absent in contrast to SiC films grown on p-type Si(111), where the deformations are formed and completely relaxed by the 40 min of synthesis. A dramatic change in the SiC film structure is observed on the third minute of the growth, which is associated with the formation and growth of pores in the SiC layer. Differences in the lattice constants of SiC films grown on p- and n-type Si substrates are determined and verified via analysis of the change in the curvature of SiC/Si wafers. Keywords: Silicon carbide on silicon, elastic strain, nanostructures, microstructure evolution.

Review of effective techniques for surface engineering material modification for a variety of applications

<abstract> <p>The status of current advances in modifying surfaces for the protection of materials is reviewed in this research. The main goal of material selection is to improve and reinforce surface functionalities. A few examples of surface modification techniques include sol-gel, cladding, electroplating, plasma and thermal spraying, physical deposition of vapors (PVD), vapor chemical deposition (CVD) and beam electron physical vapor deposition (EB-PVD). Strengthening by flame, induction, laser or electron beam is one type of surface modification procedure. Other types include plasma-immersed ion implantation and ion implantation at high energies, as well as diffusion treatments like carburizing and nitriding. Friction control, improved surface corrosion and wear resistance and changes to a component's mechanical or physical qualities are all possible using surface modification methods. The study also contains contemporary research in laser therapy, PVD, EB-PVD, thermal spraying and ion implantation. Additionally, magnetron sputtering (MS) is a widely used and successful approach for thin film coating in the current study. It is crucial to remember that each approach has a distinct set of restrictions, and the method's parameters might change based on the one that is selected, such as deposition targets, overall vacuum substrate temperature, reactive or mixed gas type, pressure percentage and bias voltage, which all have impacts on the PVD technique's layer qualities. Phase formation, change in phase, hardness and film structure of monolayer and multilayer films formed on the substrate under various circumstances also cause variations in the characteristics. Additionally, ion implantation enhances the surface characteristics of layers by implanting ions such as N<sup>+</sup>, B<sup>+</sup>, C<sup>+</sup>, etc. The study shows that the higher layers of multilayer enhance the degree of hardness and lower friction coefficients. To enhance the protection of thermal resistance, a thermal spraying barrier coating was coated on substrate nickel-base alloys, and the surface materials' texture, hardness and wear rate were altered by laser beam. Additionally, a heat pipe's performance was improved by a factor of 300 by adding a tiny coating of gold.</p> </abstract>

Изменение упругих деформаций в пленках SiC в процессе роста методом согласованного замещения атомов на подложках Si

Sequential stages of synthesis of SiC epitaxial films on n- and p-type Si(111) substrates in a mixture of carbon monoxide and silane are studied by X-ray diffraction (XRD) and Raman scattering methods. It was found that the elastic strain in SiC films grown on n-type Si(111) is absent in contrast to SiC films grown on p-type Si(111), where the deformations are formed and completely relaxed by the 40th minute of synthesis. A dramatic change in the SiC film structure is observed on the third minute of the growth, which is associated with the formation and growth of pores in the SiC layer. Differences in the lattice constants of SiC films grown on p- and n-type Si substrates are determined and verified via analysis of the change in the curvature of SiC/Si wafers.

Ionic liquid modulation of exchange bias in epitaxial LaMnO3 thin films

The magnetic ground state of LaMnO3 (LMO) thin film is still a controversial issue, even though various mechanisms, such as cation/anion non-stoichiometry, epitaxial strain, interfacial charge reconstruction, and orbital ordering, have been proposed. Here, exchange bias (EB) was introduced into a high-quality epitaxial LMO thin film via relatively low oxygen growth pressure. The EB in LMO was modulated by +2 V gating via ionic liquid method with increased EB field (HEB), coercivity (HC), blocking temperature (TB), and reduced ferromagnetic (FM) magnetization. However, the −2 V gating has a much weaker tunability. By investigating the change of structure, surface morphology, and Mn oxidation state in LMO thin films, the modulation of magnetic properties is attributed to the creation/annihilation of oxygen vacancy in an LMO thin film. The suppressed FM phase in LMO can be ascribed to reduced Mn valence, structure disorders, and structure transition. However, the enriched antiferromagnetic phase results from the transition of the pseudocubic structure to the distorted orthorhombic structure. This work not only highlights the importance of functional defects in perovskite oxides but also sheds light on the potential of electric-field modulation of magnetism in spintronic devices.

The enhancement and regulation of lasing in dye-doped multi-layer polymer film systems

As a new research hotspot in nano-materials and nano-structures, photoluminescence is widely used in medical imaging, biosensors, integrated devices and other fields because of its excellent optical performance and good stability. The design and fabrication of these nanostructures are expensive and complex, meanwhile, the influence of film structure change on lasing characteristics has not been systematically summarized. Thus, there are still challenges to realizing lasing regulation by using a multilayer film system. In this study, a dye-doped multilayer system was prepared by a convenient spin-coating method on polyethylene glycol terephthalate (PET) film. The effects of sandwich-like film and Au nanoparticles on the lasing characteristics were studied. The results show that the sandwich-like film can form a mirror symmetry plane and increase the photon scattering frequency. Furthermore, the band-gap edge effect can effectively improve the photon gain, enhancing the optical feedback and realizing band-edge lasing. The lasing intensity in the sandwich-like film is nearly 30% higher than that of the bilayer film system at the same pump energy. By adding Au nanoparticles as scatterers, the local electromagnetic field can be enhanced because of the surface plasmon resonance, improving the transition rate of dye molecules. Meanwhile, the photon scattering frequency among the scattering cross-section can also be increased, increasing the interaction between photons and dye. The lasing intensity can be enhanced by 160% at the same pump energy because of the interaction between the plasmon resonance effect and the scattering effect. The fabrication method in this study is convenient and easy to implement, which is conducive to improving the lasing intensity and provides an effective technical way for the realization of a modulated random laser.

P‐130: Organic Thin Films for OLED Applications: Simulating the Influence of Deposition Conditions and Substrate

Organic light‐emitting diodes (OLEDs) are fabricated using a stepwise process, where layers are deposited on top of previous layers. Each of these deposition steps introduces changes to the film structure, both in the crystal structure and in the growth direction. These changes in film structure have dramatic influences on the overall performance of practical devices.