Structure Of Films Research Articles

Atom Probe Tomography of the LiFePO4-Electrolyte Interface Enabled by Thin Film Electrodes

Atom probe tomography (APT) can yield three-dimensional tomographic images at atomic-scale resolution and low-AMU elements such as Li are readily observed, making it a powerful tool for exploring battery materials interfaces. However, it is difficult to prepare APT specimen tips containing the interface of interest starting with typical particle-based battery electrodes. Here we demonstrate a methodology for reliable APT imaging of battery interfaces in which a thin film electrode geometry is used to provide well-controlled planar interfaces that are ideal for APT sample preparation and imaging. LiFePO4 (LFP) thin film electrodes, synthesized using pulsed laser deposition (PLD), were studied as an example system, with standard Li-salt electrolytes. For the results to be applicable to conventional particulate electrodes, it is important to obtain representative thin film structure and electrochemical characteristics. Thus, the effects of PLD conditions including substrate temperature, substrate crystallinity, target composition, and deposition time (number of laser pulses) on the thin film’s crystallographic texture, morphology, and electrochemical performance were studied. Optimized LFP film showed good crystallinity with low-C-rate capacity of ∼90 mAh g−1. Initial APT three-dimensional imaging of the LFP/electrolyte interface shows an ∼10 nm cathode-electrolyte interphase layer that is enriched in F and Li.

Heteroepitaxial growth of Ga2O3 thin films on Al2O3(0001) by ion beam sputter deposition

Deposition of epitaxial oxide semiconductor films using physical vapor deposition methods requires a detailed understanding of the role of energetic particles to control and optimize the film properties. In the present study, Ga2O3 thin films are heteroepitaxially grown on Al2O3(0001) substrates using oxygen ion beam sputter deposition. The influence of the following relevant process parameters on the properties of the thin films is investigated: substrate temperature, oxygen background pressure, energy of primary ions, ion beam current, and sputtering geometry. The kinetic energy distributions of ions in the film-forming flux are measured using an energy-selective mass spectrometer, and the resulting films are characterized regarding crystalline structure, microstructure, surface roughness, mass density, and growth rate. The energetic impact of film-forming particles on the thin film structure is analyzed, and a noticeable decrease in crystalline quality is observed above the average energy of film-forming Ga+ ions around 40 eV for the films grown at a substrate temperature of 725 °C.

The role of microfaceting in heteroepitaxial interfaces

We investigate the effects of microfaceting on the orientation and interface structure of fcc films on fcc substrates by molecular dynamics simulations and atomic resolution electron microscopy. For (110) substrates, the simulations reveal a misorientation between film and substrate lattices that undergoes a sudden change when interfacial facets approach the “magic size”, where a lattice dislocation minimizes the strain energy by compensating the misfit between film and substrate. For a large misfit, the angle of misorientation varies between zero and several degrees, depending on the size and sequence of microfacets. Experimental observations of interfaces in Ag/Ni near the Ni(110) orientation uncover the presence of magic-size {111} facets and show how microfaceting controls the partitioning of misfit dislocations. For facets smaller than the magic size, misfit may be compensated by partial rather than perfect dislocations. In vicinal {hhl} interfaces, made of {111} terraces separated by single-layer steps, a partial dislocation per terrace leads to film growth in the heterotwin orientation. This concept explains a range of previous results on interface structures in a variety of heteroepitaxial systems.

Phase Composition and Structure of Ultrathin Nanocrystalline Cu-Ni Film Alloys

The results of studying the morphology, crystal structure and phase composition of ultrathin Cu-Ni alloy films with thicknesses up to d = 10 nm and concentrations 0 < Cu < 100 at.% are presented.

IMPLEMENTATION OF MAGNETRON SPUTTERING METHOD IN OBTAINING A RADIO-ABSORBING THIN FILM BASED ON CoC

This paper describes the main results of the study of obtaining samples of radio-absorbing CoC films by magnetron sputtering and evaluates the data of experimental and computational studies on the relationship between the structure and properties of CoC films. To eliminate the ferromagnetic effect of cobalt, a composite target was used. The use of the composite target during magnetron sputtering ensures the production of films of a given and necessary composition. Structural-phase state of the obtained films was studied using XRD, SEM and TEM methods. A distinctive feature of the synthesized coating is the absence of a crystalline structure in some areas due to the amorphizing properties of cobalt and its tendency to form metallic glasses. Results obtained by the experiments are in good agreement with computational modeling results. The radio-absorbing properties of the obtained films were confirmed by the results of measuring the reflection loss, standing wave ratio, reflectance, and impedance. Results presented in the article can serve as a baseline for perspective studies in this field.

Assessing the Effect of Twisting and Twisting Fatigue on ZnO:Al Thin Film Performance on PEN and PET Substrates.

This study examines the electromechanical characteristics of aluminium-doped zinc oxide (AZO) films. The films were produced using the RF magnetron sputtering process with a consistent thickness of 150 nm on various polymer substrates. The study focuses on assessing the electro-mechanical failure processes of coated segments using flexible substrates, namely polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), with a specific emphasis on typical cracking and delamination occurrences. This examination involves conducting twisting deformation together with using standardised electrical resistance measurements and optical microscope monitoring instruments. It was found that the crack initiation angle is mostly dependent on the mechanical mismatch between the coating and substrate. Higher critical twisting angle values are observed for the AZO/PEN film during twisting testing. Relative to the perpendicular plane of the untwisted sample, it was found that cracks initiated at a twist angle equal to 42° ± 2.1° and 38° ± 1.7° for AZO/PEN and AZO/PET, respectively, and propagated along the sample length. SEM images indicate that the twisting motion results in deformation in the thin film material, leading to the presence of both types of stress in the film structure. These discoveries emphasise the significance of studying the mechanical properties of thin films under different stress conditions, as it can impact their performance and reliability in real-world applications. The electromechanical stability of AZO was found to be similar on both substrates during fatigue testing. Studying the electromechanical properties of various material combinations is important for selecting polymer substrates and predicting the durability of flexible electronic devices made from polyester.

Effect of camellia oil body-based oleogels on the film-forming properties of soy protein isolate

Soybean protein isolate (SPI) was frequently used to make edible films due to its highly degradability and excellent film forming ability. However, the limited barrier properties and low tensile strength of SPI films prevent their application in food packaging. In this study, the SPI film was modified by blending camellia oil body-based oleogel (COBO). COBO improved the mechanical properties of SPI film and increased its light-blocking, water insolubility and barrier properties. Micrograph, particle size distribution, protein conformation and crystalline structure analysis illustrated that camellia saponin in COBO formed hydrogen bonds with SPI, significantly reduced the particle size of the film-forming emulsion, and enhanced the order and uniformity of composite films structure, thus improved the overall performance of the SPI films. The SPI-COBO film packing delayed the weight loss, total soluble solids content increase, and the decrease in hardness of stored strawberries. This study puts forwards a new approach for SPI film modification by blending natural emulsified lipids, contributing to the development of sustainable packaging alternatives.

The influence of aluminum on the morphological, optical properties and electronic structure of ZnO thin films

The influence of aluminum on the morphological, optical properties and electronic structure of ZnO thin films

Atomic-scale understanding on the influence of sliding angle on the interfacial structure and friction behavior of textured amorphous carbon films

Textured amorphous carbon (T:a-C) films have received great attention in the fields of hard drives, MEMS, and NEMS due to their excellent tribological properties. However, there is still a lack of research on the dependence of its friction behavior on different sliding angles. Especially, owing to the limitations of in-situ characterization in capturing the friction interface information, the potential friction mechanisms are still unclear. Hence, in this work T:a-C film with a rectangular shape was constructed and the impact of different sliding angles on friction behavior under dry friction condition was mainly explored through reactive molecular dynamics simulation. Results unveil that the friction properties of T:a-C films are closely dependent on the sliding angle. When the sliding angle increases from 0° to 45°, the decrease in the number of CC covalent bonds at the friction interface weakens the interfacial crosslinking effect, leading to a decrease in the friction coefficient by 20.11 %. However, as the sliding angle further increases from 45° to 90°, an increase in friction coefficient is observed, which is due to the increase of unsaturated bond content, weakening the interface passivation effect. These results reveal the friction mechanism of T:a-C films, induced by sliding angle, and effectively guide the design and technical application of textured a-C films.

Research Progress on the Oxidation Behavior of Ignition-Proof Magnesium Alloy and Its Effect on Flame Retardancy with Multi-Element Rare Earth Additions: A Review.

The phenomenon of high-temperature oxidation in magnesium alloys constitutes a significant obstacle to their application in the aerospace field. However, the incorporation of active elements such as alloys and rare earth elements into magnesium alloys alters the organization and properties of the oxide film, resulting in an enhancement of their antioxidation capabilities. This paper comprehensively reviews the impact of alloying elements, solubility, intermetallic compounds (second phase), and multiple rare earth elements on the antioxidation and flame-retardant effects of magnesium alloys. The research progress of flame-retardant magnesium alloys containing multiple rare earth elements is summarized from two aspects: the oxide film and the matrix structure. Additionally, the existing flame-retardancy models for magnesium alloys and the flame-retardant mechanisms of various flame-retardant elements are discussed. The results indicate that the oxidation of rare earth magnesium alloys is a complex process determined by internal properties such as the structure and properties of the oxide film, the type and amount of rare earth elements added, the proportion of multiple rare earth elements, synergistic element effects, as well as external properties like heat treatment, oxygen concentration, and partial pressure. Finally, some issues in the development of multi-rare earth magnesium alloys are raised and the potential directions for the future development of rare earth flame-retardant magnesium alloys are discussed. This paper aims to promote an understanding of the oxidation behavior of flame-retardant magnesium alloys and provide references for the development of rare earth flame-retardant magnesium alloys with excellent comprehensive performance.

Ultrahigh Bipolar Photoresponse in a Self-Powered Ultraviolet Photodetector Based on GaN and In/Sn-Doped Ga2O3 Nanowires pn junction.

Self-powered ultraviolet photodetectors with bipolar photoresponse have great potential in the fields of ultraviolet optical communication, all-optical controlled artificial synapses, high-resolution ultraviolet imaging equipment, and multiband photoelectric detection. However, the current low optoelectronic performance limits the development of such polar switching devices. Here, we construct a self-powered ultraviolet photodetector based on GaN and In/Sn-doped Ga2O3 (IGTO) nanowires (NWs) pn junction structure. This unique nanowire/thin film structure allows GaN and IGTO to dominate the absorption of light at different wavelengths, resulting in a highly bipolar photoresponse. The device has a responsivity of 2.04 A/W and a normalized detectivity of 7.18 × 1013 Jones at 254 nm and a responsivity of -2.09 A/W and a normalized detectivity of -7 × 1013 Jones at 365 nm, both at zero bias. In addition, it has an extremely high Ilight/Idark ratio of 1.05 × 105 and ultrafast response times of 2.4/1.9 ms (at 254 nm) and 5.7/5.2 ms (at 365 nm). These excellent properties are attributed to the high specific surface area of the one-dimensional nanowire structure and the abundant voids generated by the nanowire network to enhance the absorption of light, and the p-n junction structure enables the rapid separation and transfer of photogenerated electron-hole pairs. Our findings provide a feasible strategy for high-performance wavelength-controlled polarity switching devices.

Metal dependence of spontaneous graphitization growth at room temperature

The low-temperature graphene growth is a crucial step toward more efficient, cost-effective, productive, cheap, and sustainable energy systems. In this work, we report the effect of transition metal nanoparticles (TMNPs) Ag, Pd, and Cu on the graphitization of amorphous carbon (a-C) deposited onto SiO2 substrates using a one-step magnetron sputtering technique at room temperature (RT). Transmission electron microscopy (TEM), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) were used to examine the structures of TMNP-C films. The a-C around the metallic NPs spontaneously formed a disordered graphitic structure. Moreover, the 2D peak was detected in Raman spectra, and XPS analyses revealed the sp2 graphitization for the Ag-C, Pd-C, and Cu-C films deposited on the SiO2 substrates. These studies suggest that these metals’ graphitization activity is in the sequence of Pd > Cu > Ag. The highest catalytic activity of Pd NPs in graphitization at low temperatures was due to the highest carbon solubility and nano-sized particles. Thus, the control of the particle size of the catalyst to enhance the carbon solubility and decrease the melting point will open up a new strategy to grow high-quality graphene at low- temperatures.

Production of a novel biodegradable film made from chitosan and pomegranate (Punica granatum L.) seed essential oil

This study evaluated the effects of pomegranate (Punica granatum L.) seed essential oil (PSO) on chitosan-based films. The results showed that the addition of PSO slightly increased thickness, while significantly decreasing the moisture content, and solubility properties. The color values of the composite films containing PSO changed noticeably, with a tendency toward light brown, which was beneficial in resisting food decomposition caused by ultraviolet light. X-Ray diffraction analysis (XRD) and Fourier-transform Infrared (FT-IR) results indicated that the addition of PSO affected the structure of the chitosan films, while the interaction between chitosan and polyphenols in PSO established new hydrogen bonds. Scanning electron microscopy (SEM) showed that the surface of the PSO-containing blend films was rougher compared to the chitosan control film, and the roughness increased as the PSO content in the blend films increased. Additionally, composite films that contained PSO had substantial antibacterial action, particularly against pathogenic E. coli. In short, the novel active chitosan-based films with incorporated PSO present broad application prospects in the packaging of fresh-cut meat or vegetables. Therefore, this study will also be beneficial in these areas.

Corrosion behavior of Cr/RE alloyed rebar in carbonated simulated concrete pore solutions with chloride ions

This study investigated the effect of the addition of Cr and RE microalloying regarding the steel rebar's resistance to corrosion in the co-existence of carbonation and chloride ions using electrochemical tests, scanning electron microscopy and confocal laser scanning microscopy. The best corrosion resistance of the Cr/RE microalloying rebar was found by the reduction in corrosion rates and the diminution of the rust layer. And during the initial stages of localized corrosion, the corrosion pits' depth was minimized, showing lateral expansion trends, which was supported by confocal laser scanning microscopy. Additionally, XPS analysis revealed that Cr/RE microalloying rebar can change the structure of the surface oxide film with a higher Fe(II)/Fe(III) ratio, which enhanced the surface oxide film's protective qualities.

Regulation of near-infrared absorbing property for the absorptive short-wave pass filter based on Ag:1st/Si3N4/SiO2/Si3N4/Ag:2nd/Si3N4/W-WOx quasi-optical microcavity

Regulation of the near-infrared absorbing property in the different spectral ranges has been a challenge for absorptive short-wave pass filters (ASPFs) to meet the increasing application demands. In this paper, the multi-layer ASPF with the film structure of substrate(quartz)/Si3N4/ Ag:1st/Si3N4/SiO2/Si3N4/Ag:2nd/Si3N4/W-WOx/SiO2 is designed and prepared by magnetron sputtering. We get an optimal spectral selectivity in that the transmissive band ranges from 380-700 nm with a peak transmittance of 72.9 %, and the absorptive band ranges from 700-1400 nm with a peak absorptance of 84.1 %. As the main part of the ASPF, the quasi-optical microcavity (QOM) is creatively constructed with the film structure of Ag:1st/Si3N4/SiO2/Si3N4/Ag:2nd/Si3N4/W-WOx, integrating the interference mechanism and surface plasmon resonance mechanism with the intrinsic spectral selectivity of the W-WOx and silver layers, achieving the good selective absorbing property. The absorptive band is widened from 700-1400 nm to 700–2500 nm by regulating the interference effect and the intrinsic property via changing the thickness of the W-WOx layer, realizing much more significant regulation. The optical property remains stable after heat treatment at 200 °C for 72 h in the air, showing better thermal stability than other ASPFs. The outdoor thermal insulation experiments show that the temperature of black paint under the ASPF is about 17 °C lower than that under quartz glass. The microscopic and optical mechanisms for regulating the optical properties have been analyzed in-depth, providing a new strategy for the development of ASPFs.

Interfacial Distortion of Sb2Te3-Sb2Se3 Multilayers via Atomic Layer Deposition for Enhanced Thermoelectric Properties.

Atomic layer deposition (ALD) is an effective technique for depositing thin films with precise control of layer thickness and functional properties. In this work, Sb2Te3-Sb2Se3 nanostructures were synthesized using thermal ALD. A decrease in the Sb2Te3 layer thickness led to the emergence of distinct peaks from the Laue rings, indicative of a highly textured film structure with optimized crystallinity. Density functional theory simulations revealed that carrier redistribution occurs at the interface to establish charge equilibrium. By carefully optimizing the layer thicknesses, we achieved an obvious enhancement in the Seebeck coefficient, reaching a peak figure of merit (zT) value of 0.38 at room temperature. These investigations not only provide strong evidence for the potential of ALD manipulation to improve the electrical performance of metal chalcogenides but also offer valuable insights into achieving high performance in two-dimensional materials.

Modification of a Carboxymethyl Cellulose/Poly(vinyl alcohol) Hydrogel Film with Citric Acid and Glutaraldehyde Crosslink Agents to Enhance the Anti-Inflammatory Effectiveness of Triamcinolone Acetonide in Wound Healing.

Anti-inflammatory wound healing involves targeted drug delivery to the wound site using hydrogel materials to prolong drug effectiveness. In this work, hydrogel films were fabricated using carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) crosslinked with citric acid (CA) and glutaraldehyde (GA) at different concentrations. The crosslinker densities were optimized with various CA (2-10% w/v) and GA (1-5% v/v) concentrations. The optimized crosslink densities in the hydrogel exhibited additional functional group peaks in the FT-IR spectra at 1740 cm-1 for the C=O stretching of the ester linkage in CA and at 1060 cm-1 for the C-O-C stretching of the ether group in GA. Significantly, the internal porous structures of hydrogel composite films improved density, swelling capacities, solubility percentage reduction, and decreased water retention capacities with optimized crosslinker densities. Therefore, these hydrogel composite films were utilized as drug carriers for controlled drug release within 24 h during medical treatment. Moreover, the hydrogel films demonstrated increased triamcinolone acetonide (TAA) absorption with higher crosslinker density, resulting in delayed drug release and improved TAA efficiency in anti-inflammatory activity. As a result, the modified hydrogel showed the capability of being an alternative material with enhanced anti-inflammatory efficiency with hydrogel films.

Microstructures and tribological properties of MoS2/Mo2N multilayer gradient films deposited by reactive magnetron sputtering

In order to compare the microstructures and tribological properties of films, pure Mo2N, pure MoS2, 3-layer and 13-layer MoS2/Mo2N gradient films were deposited by reactive magnetron sputtering. The crystalline structure, surface and cross-section morphologies, 3D surface topography, binding energy, hardness and tribological properties of films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atom force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), nanoindenter, and wear tester, respectively. The results indicate that the preferred orientation of MoS2 in gradient films has changed. The surface and cross-section structures of gradient films become denser with increasing the number of gradient layers. Average surface roughness (Ra) of pure MoS2 film is the highest, and Ra of 13-layer film is the lowest. The binding energy of MoS2 in the composite layer of gradient film has changed. The hardness of gradient film is higher than that of MoS2 and lower than that of Mo2N. The wear resistance of gradient films is much better than that of pure MoS2, and this phenomenon is more obvious under high load conditions. The improvement in the wear resistance of gradient films is attributed to the increase of dense, hardness, H/E and H3/E2. In the initial stage of friction, the 3-layer gradient film can maintain low friction coefficient (≤0.15), which is attributed to the thick MoS2 surface layer. The wear resistance of 13-layer is much better than that of 3-layer gradient film, because it has higher hardness, higher H/E and H3/E2 than 3-layer gradient film.

Multiparticle Synergistic Electrophoretic Deposition Strategy for High-Efficiency and High-Resolution Displays.

Colloidal nanoparticles offer unique photoelectric properties, making them promising for functional applications. Multiparticle systems exhibit synergistic effects on the functional properties of their individual components. However, precisely controlled assembly of multiparticles to form patterned building blocks for solid-state devices remains challenging. Here, we demonstrate a versatile multiparticle synergistic electrophoretic deposition (EPD) strategy to achieve controlled assembly, high-efficiency, and high-resolution patterns. Through elaborate surface design and charge regulation of nanoparticles, we achieve precise control over the particle distribution (gradient or homogeneous structure) in multiparticle films using the EPD technique. The multiparticle system integrates silicon oxide and titanium oxide nanoparticles, synergistically enhancing the emission efficiency of quantum dots to a high level in the field. Furthermore, we demonstrate the superiority of our strategy to integrate multiparticle into large-area full-color display panels with a high resolution over 1000 pixels per inch. The results suggest great potential for developing multiparticle systems and expanding diverse functional applications.

Structure and Superconductivity of Epitaxial and Polycrystalline VN Thin Films

Structure and Superconductivity of Epitaxial and Polycrystalline VN Thin Films