Structure Of Films Research Articles

Pinning of domain walls in epitaxial garnet film patterned by surface arrays of ferromagnetic metal particles

Rare-earth iron garnet epitaxial films famous for their unique magnetic, microwave and optical properties consistently attract high interest. Domain structure of both bulk and interfaces of garnet films is closely connected with their magnetic properties and magnetization dynamics. In this work, we investigate the magnetic behaviour and domain structure of an epitaxial bismuth-substituted lutetium iron garnet film with a regular array of planar submicron particles made of Co film or Co/Pt multilayer on its surface. Optical polarization microscopy and magnetic force microscopy techniques used for the characterization of these composite structures confirm the mutual influence of the garnet and metal nanostructured layers on each other. On the one hand, dense ordered metal particles provide the pinning of the surface magnetic domains of the garnet film, which further affects the organization of the bulk stripe domains. On the other hand, we observed that the domain structure in the metallic pattern is governed by the domain structure of the garnet placed beneath it.

Metal-semiconductor-metal UVA photodetector based on TiO2 thin films synthesized via liquid phase deposition method

In this work, titanium dioxide (TiO2) thin film-based metal-semiconductor–metal (MSM) ultraviolet (UV) photodetectors (PDs) were fabricated on glass substrates via liquid phase deposition (LPD) technique at various deposition time in the range of 3–6 h. Varying deposition time significantly impacted the physical properties of the films. Increasing the deposition time revealed a mixture of clusters and hexagonal-like structures in film’s morphology. The energy band gap of the TiO2 films decreased from 3.30 to 3.09 eV upon increasing the deposition time. Photodetection characteristics were examined by exposing the MSM UV PD to 390 nm UV light with an intensity of 1.6 mW cm−2 and a bias voltage of 5 V. The fabricated PDs implied characteristics of I-V ohmic contact. The optimum photodetection characteristics were achieved for TiO2 film deposited at 6 h which exhibited 36.9 μA maximum photocurrent, 20080.3% sensitivity, 201.80 gain, 225 mA W−1 responsivity, 81.07% external quantum efficiency, 0.276 s response time, and 0.274 s recovery time. The photoelectric properties of the films were strongly affected by the increased grain size and improved crystallinity of the films due to the prolonged deposition time. The optimum film demonstrated its potential to be a promising candidate for UV PD applications.

Preparation and properties of fluorinated VAc-VeoVa10 latex emulsified with allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulphate

Purpose The traditional VeoVa10-VAc copolymer latex, which prepared via the emulsion polymerization of the mixed monomers of VAc and VeoVa10, has the poor water resistance and thermal stability because of the migration of the conventional emulsifier molecules and the low bond energy of C-C bond. The purpose of this work is that the fluorinated monomer is used to modify the latex. The film of the resultant latex has the C-F bond with high bond energy and low surface energy, which can effectively improve the heat resistance and water resistance of the resultant film. In addition, the reactive emulsifier is used to replace the conventional emulsifier. The drawbacks of the conventional emulsifier molecules migrate and desorb can be avoided when the polymer latex is stored, thereby also improving the water resistance. Design/methodology/approach The modified VAc-VeoVa10 latex has been successfully synthesized via the semi-continuous seeded emulsion polymerization, which VAc and VeoVa10 is used as the main monomers and HFMA was used as the functional monomer. KPS and reactive surfactants of SE-10 were used as the initiator and emulsifier, respectively. The structure of resultant latex film was characterized by Fourier transform infrared spectroscopy (FTIR). The latex films were tested by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA). The particle size and its distribution of the latex were measured by the nano particle size analyzer. Findings The factors that had an influence on the properties of the latex and the film were investigated in detail. The stability of the resultant latex is good. The average particles of the latex and its distribution are small and uniform, respectively. In comparison with the conventional latex film, the thermal stability and hydrophobicity of the resultant latex film are improved obviously. Practical implications The resultant latex can be used in both the waterborne interior and exterior wall coatings, pickering stabilized waterborne polymer dispersions, polymer powders, environmentally friendly polymer-modified waterproof mortar and other fields, which can be satisfied with the high demand of thermal stability and hydrophobicity. Originality/value The modification of poly (VAc-VeoVa10) by reactive surfactant and fluorinated monomer is seldom reported. In this study, the fluorinated poly (VAC-VeoVa) latex is prepared via the reactive surfactants, which VAc and VeoVa10 is used as the main monomers and hexafluorobutyl methacrylate is used as the functional monomer. Potassium persulfate (KPS) and allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulfate are used as the initiator and emulsifier, respectively.

Modeling the influence of technological parameters of the magnetron sputtering process using the Caroline D12C system on the proportion of nanocrystallites in the structure of thin silicon films

Modeling the influence of technological parameters of the magnetron sputtering process using the Caroline D12C system on the proportion of nanocrystallites in the structure of thin silicon films

Impact of Silver Incorporation and Flash-Lamp-Annealing on the Photocatalytic Response of Sputtered ZnO Films.

Thin films of silver-doped zinc oxide (SZO) were deposited at room temperature using a DC reactive magnetron co-sputtering technique using two independent Zn and Ag targets. The crystallographic structure, chemical composition and surface morphology of SZO films with different silver concentrations were correlated with the photocatalytic (PC) properties. The crystallization of the SZO films was made using millisecond range flash-lamp-annealing (FLA) treatments. FLA induces significant structural ordering of the wurtzite structure and an in-depth redistribution of silver, resulting in the formation of silver agglomerates. The wurtzite ZnO structure is observed for silver contents below 10 at.% where Ag is partially incorporated into the oxide matrix, inducing a decrease in the optical band-gap. Regardless of the silver content, all the as-grown SZO films do not exhibit any significant PC activity. The best PC response is achieved for samples with a relatively low Ag content (2-5 at.%) after FLA treatment. The enhanced PC activity of SZO upon FLA can be attributed to structural ordering and the effective band-gap narrowing through the combination of silver doping and the plasmonic effect caused by the formation of Ag clusters.

Insight into wave propagation in polyimide films and resistive grid sandwich structures towards a hybrid monitoring of hypervelocity impact

Micro-Meteoroid and Orbital Debris pose a significant threat to the safe operation of orbiting spacecraft, potentially leading to mission failure in space exploration. Quantitative characterization of hypervelocity impact (HVI) is crucial to ensure the safety and successful completion of on-orbit missions. Firstly, this study designed a three-layer sandwich structure of polyimide film with orthogonally laid resistive wires, combined with piezoelectric and resistive wire sensors, for the simultaneous acquisition of acoustic emission (AE) signals generated by HVI and measurement of perforation dimensions. Secondly, a semi-analytical finite element (SAFE) analysis of wave dispersion properties in the periodic sandwich structure is conducted with Bloch’s theorem, together with a hybrid model based on three-dimensional smoothed particle hydrodynamics and finite element methods (SPH-FEM) to comprehensively understand the AE waves and damage characteristics induced by HVI. The resulting anisotropic wave propagation characteristics with SAFE and SPH-FEM are closely matched. Thirdly, a time delay-multiplication (TDM) imaging algorithm considering wave velocity anisotropy is proposed for accurate real-time “visualization” of HVI locations. Lastly, correlations are established between projectile and perforation dimensions. The proposed algorithm for HVI multi-parameter quantification and damage detection helps evaluate the space HVI environment and HVI-induced damage to spacecraft.

Novel electrochromic-supercapacitor device based on P(TPACz)/WO3-PDA nanocomposite film

Organic–inorganic composites of (E)-3,5-di(9 H-carbazol-9-yl)-N-(4-(diphenylamino)benzylidene)aniline/dopamine-modified WO3 (P(TPACz)/WO3-PDA) were prepared by electrochemical polymerisation. The as-prepared P(TPACz)/WO3-PDA composites showed good electrochromic and electrochemical performance. The prominent electrochemical performance of P(TPACz)/WO3-PDA represents a high areal capacitance (32.15 mF cm−2 at 0.1 mA cm−2) and wide range of potential windows (-2.0−1.6 V). Additionally, symmetric supercapacitor devices based on P(TPACz)/WO3-PDA composite films were successfully constructed, which exhibited a high specific capacitance (13.88 mF cm−2 at 0.02 mA cm−2) and an energy density of 7.71 × 10−3 mWh cm−2 in n-doped station. The remarkable electrochromic and electrochemical performances are due to the synergy between the organic polymer and WO3-PDA. A complete large-area composite film structure with high conductivity promises fast electronic transport. This study provides a method for preparing multifunctional composite electrode materials, offering technical support for intelligent displays and energy storage technologies.

Preparation and characterization of a multifunctional film with excellent UV shielding, antibacterial and antioxidant capabilities containing cinnamaldehyde and titanium dioxide (TiO2)

AbstractSoy protein isolated (SPI) have a wide application in the food packaging, but their water resistance, mechanical properties and antibacterial properties are not ideal for directly use. In our study, we developed a series of SPI composite films loaded with cinnamaldehyde and titanium dioxide (TiO2). X‐ray diffraction (XRD), UV scanning spectra (UV) and spectro colorimeter were applied to indicate the structure of films. The incorporation of TiO2 (0.5%) caused a subsequent effect on the tensile property, UV blocking properties and water vapor properties (WVP). On the other hand, SPI film composed with a constant amount of TiO2 and different concentration of cinnamaldehyde showed an excellent synergistic effect to improve the tensile property, moisture content, UV blocking properties, water vapor properties and morphological characteristics. Furthermore, the composite films exhibited superior antibacterial activity when tested against both S. aureus and E. coli. The microstructure of the composite film become heterogeneous and rough after addition of TiO2 and cinnamaldehyde compare to control film. The findings of the present study may facilitate a re‐evaluation of the potential of using multiple compounds to prepare active edible films.

Comparative Study and Analysis of Social Structure and Cultural Values in Chinese and Korean Movies

A comparative study of social structure and cultural values in Chinese and Korean films reveals the unique perspectives and profound differences between the two countries in reflecting social reality and conveying cultural values in their films. Chinese movies tend to depict harmonious and intimate family relationships when showcasing family structure, emphasizing the importance of the family as an individual's emotional support and spiritual sustenance. Korean movies, on the other hand, focus more on showcasing the complexity and conflicts within families, reflecting social reality and the depth of human nature through the entanglements among family members. This difference reflects the different emphasis on family values and social values between China and South Korea. In terms of social class, Chinese movies often focus on the survival status and struggle process of the lower class society, showcasing social injustice and contradictions by telling stories of ordinary people. This kind of attention reflects the humanistic care of Chinese films towards vulnerable groups and their profound reflection on social issues. Korean movies, on the other hand, tend to reveal and criticize the power and corruption of the upper class, reflecting the dark side of society by depicting social phenomena such as collusion between politics and business, and power and money transactions. This difference reflects the different orientations of social class concepts and social responsibility between China and South Korea.

Features of the structure and resistive switching of titanium oxide films on Y-cut piezoelectric substrate of a LiNbO3 crystal

The difference in the structure of titanium oxide thin films deposited on fused silica substrates and the Y-cut of a lithium niobate crystal is demonstrated. In both cases, the film is amorphous; however, an insignificant amount of rutile crystallites is observed in the film formed on the Y-cut of the lithium niobate crystal. It is shown that the electrical characteristics of the films depend not only on the material of the substrate, but, in the case of the lithium niobate substrate, also on the direction of an electric field. This is caused by the deformation of the substrate due to the inverse piezoelectric effect.

Comprehensive analysis of charge carriers dynamics through the honeycomb structure of graphite thin films and polymer graphite with applications in cold field emission and scanning tunneling microscopy

Polymer graphite electron sources have performed satisfactorily as field emission emitters and scanning tunneling microscopy probes in the past few years. However, the emission process was characterized by limited total emission currents. This paper introduces the elemental, vibrational, electronic structure, and optical analysis of polymer graphite and glass-graphite composite field emission cathodes to study these limitations. Moreover, the field emission characteristics are studied including the changes in the potential energy barrier of the used materials and structures. Among the studied structures, the cathodes prepared from graphite thin films deposited on a micropointed glass substrate (film-GMF) showed superior performance as random field emission arrays. This includes obtaining much higher emission current values ≈ 20 times) and lower threshold voltages ≈ 1/2) compared to the results obtained from polymer graphite samples. The enhancement factor in such emitters is believed to be the three-dimensional honeycomb structure of graphite. Moreover, the study includes applying graphite coatings to tungsten nano-field emission cathodes and scanning tunneling microscopy probes, which improves the performance of such cathodes/probes in both microscopic techniques.

Study of endogenous chloride ion content on the behavior of steel bar depassivation in sea sand concrete

In this study, we investigated the chloride concentration in sea sand that induces corrosion in steel bars, as well as the corrosion mechanisms of steel bar within sea sand concrete. Different analytical techniques indicated that the chloride concentration for steel bar corrosion in sea sand concrete was 0.03 % (when the water-binder ratio was in the range of 0.4–0.6). First, the calcium silicate in sea sand concrete reacted with Fe3+ to reduce the compactness of the oxide layer and increase the corrosion risk of steel bars. Second, as the water-binder ratio and chloride concentration gradually increased, the loose structure of the passive film increased, and the relatively dense structure decreased, which made it easier for chloride ions to penetrate the outer layer of the passive film to erode the steel matrix. Besides, the reaction of chloride ions with C3A to form Friedel's salt optimized the pore structure and reduced the content of free chloride ions. However, the adverse effect of chloride ions on the passive film of steel bars exceeded the beneficial impact of porosity reduction. These findings allow us to better apply sea sand to improve the sustainable development of environment.

Topochemical Polymerization at Diacetylene Metal-Organic Framework Thin Films for Tuning Nonlinear Optics.

Developing the topochemical polymerization of metal-organic frameworks (MOFs) is of pronounced significance for expanding their functionalities but is still a challenge on third-order nonlinear optics (NLO). Here, we report diacetylene MOF (CAS-1-3) films prepared using a stepwise deposition method and film structural transformation approach, featuring dynamic structural diversity. The MOF structures were determined by the three-dimensional electron diffraction (3D ED) method from nanocrystals collected from the films, which provides a reliable strategy for determining the precise structure of unknown MOF films. We demonstrate the well-aligned diacetylene groups in the MOFs can promote topological polymerization to produce a highly conjugated system under thermal stimulation. As a result, the three MOF films have distinct NLO properties: the CAS-1 film exhibits saturable absorption (SA) while CAS-2 and CAS-3 films exhibit reverse saturable absorption (RSA). Interestingly, due to the topochemical polymerization of the MOF films, a transition from SA to RSA response was observed with increasing temperatures, and the optical limiting effect was significantly enhanced (∼46 times). This study provides a new strategy for preparing NLO materials and thermally regulation of nonlinear optics.

Flexible Near‐Infrared Organic Photodetectors With Ultralow Dark Current by Layer‐by‐Layer Blade Coating

AbstractNear‐infrared organic photodetector (NIR OPD) is promising for emerging wearable biosensing applications. However, their practical application is hindered by the high dark currents of devices that limit the detection of faint light. In this work, highly sensitive flexible NIR OPDs are presented with ultralow dark currents, fabricated using a layer‐by‐layer blade coating (LBL‐BC) technique. In the active layer, a fully fused‐ring molecule FM2, featuring a fixed molecular skeleton, is employed as an electron acceptor to reduce the trap density. The LBL‐BC method enhances the film order and phase purity of the active layer, significantly reduces the trap density of states, and optimizes the vertical phase separation structure of the thin film, thereby preventing reverse charge injection. As a result, a highly sensitive flexible NIR OPD is developed exhibiting an ultralow dark current density of 4.83 × 10−9 A cm−2 at −0.3 V bias and an extremely low noise current density of 7.65 × 10−15 A Hz−1/2 at 10 Hz, comparable to commercial silicon photodiodes. Furthermore, this flexible device is successfully applied for real‐time monitoring of human heartbeat rate, oxygen saturation, and motion recognition. These findings advance the development of highly sensitive NIR OPDs and their application in wearable biosensing technologies.

Selectable growth and electronic structures of two-dimensional layered InSe and In2Se3 films

Selectable growth and electronic structures of two-dimensional layered InSe and In2Se3 films

Transmission anomalies in 2D photonic crystals from the checkerboard family: from broken to hidden symmetries and plasmon “spoofing”

In a field representation, the main symmetry of the electromagnetic response of complementary metal film structures is described by the Babinet principle, which is expected to be strictly obeyed by structures in vanishingly thin films of a perfect electric conductor. On the other hand, a softer version of this based on transmittance, the transmittance Babinet principle (TBP), is not so restrictive. The goal of this work is to study how severely this broken symmetry affects the optical response of such structures. We consider two geometrically distinct series of planar complementary structures from the checkerboard family: regular and bowtie. The self-complementary structure of these series is known to be very singular and breaks even the rigorous Babinet principle. Here, we study complete simulated transmittance spectral maps (T-Maps), which accumulate the whole spectral response of an entire series of structures in a single plot. The ab initio simulated T-Maps of these 2D photonic crystals were simulated for linearly polarized waves propagating perpendicular to these planar structures, made in a vanishingly thin film of a perfect electric conductor. While we confirm the expected long wavelength validity of the TBP, we show that in the frequency range where diffraction effects dominate, the standard derivation of the TBP no longer applies, and with the help of our T-Maps, we demonstrate a total collapse of the TBP in the structures considered. We show that this broken symmetry practically eliminates all but one transmission band on the hole side of the T-Maps and that the remaining strong band is a “spoof” plasmon, free of multiple frequency replicas, an important feature for optical filter applications. In addition, by symmetry arguments and simulations, we discovered that the T-Maps for bowtie and doubled-period regular structures are identical. We discuss how this hidden symmetry can benefit various applications by providing a convenient scaling, whereby simplified structures can deliver a tailored response.

Thermal stress concentration points and stress mutations in nano-multilayer film structures

Abstract In the multilayer film-substrate system, the buckling, delamination and cracking of the film caused by the thermal stress concentration point and the stress mutation are the main factors leading to the failure of the corresponding device function. In this paper, we studied the multilayer film system composed of the substrate and the three-layer film. The thermal stress distribution inside the structure was calculated by the finite element method (FEM). It was observed that there was a large thermal stress difference between the layers. This is mainly due to the mismatch of thermal expansion coefficient (CTE) between materials. Different materials have different degrees of change with the external environment temperature, and the layers are squeezed. In particular, there are obvious thermal stress concentration points at the corners of the base layer and the transition layer, which is due to the sudden change of the shape at the geometric section of the structure, resulting in a sudden increase in local stress. In order to solve this problem, we have chamfered the substrate and added an intermediate layer between the substrate and the transition layer to analyze whether the difference between the thermal stress concentration point and the thermal stress can be reduced or eliminated, and the service life of the multilayer structure can be extended. The conclusion shows that chamfering and increasing the intermediate layer can reduce the stress mutation and weaken the thermal stress concentration point, which can effectively improve the interlayer bonding strength.

Strategies for the incorporation of organosolv lignin in hydroxypropyl methylcellulose-based films: A comparative study

Organosolv lignin extracted from vine pruning residues was added to hydroxypropyl methylcellulose (HPMC)-based films using three strategies: i) lignin incorporated into the film (lignin-based film), ii) lignin nanoparticles (LNPs) incorporated into the film (LNPs-based film), and iii) lignin coated on HPMC films' surface (lignin-coated film). The films obtained were evaluated in terms of morphology, water barrier and mechanical properties, and antioxidant capacity. Results showed that LNPs incorporation did not affect the films´ water vapour permeability (WVP). Nonetheless, the lignin-based and lignin-coated films improved the water barrier properties of HPMC-based films, achieving a 31.5 and 36 % reduction of WVP, respectively. The morphological evaluation, performed by scanning electron microscopy, revealed films' morphology changes with the lignin incorporation, which was more evident in the lignin-based films. Fourier transform infrared spectroscopy (FTIR) showed minor changes in the film's structure using the different lignin incorporation methods. The mechanical properties were improved, including a significant increase in the tensile strength in the lignin-based and lignin-coated films. All films showed high radical scavenging activity (RSA) after 24 h, with a gradual increase in the lignin-coated films over time. The lignin-coated films showed to be the most promising incorporation strategy to improve the HPMC-based film's properties.

Enhanced crystallinity of (Sr,Ba)Nb2O6 films on sapphire and alumina substrates

Barium-strontium niobate in thin film form can be considered as a prospective ferroelectric material for microwave applications due to high dielectric nonlinearity. Its performance is linked to film structure quality, and one method to achieve high-quality films on microwave substrates goes through the process of annealing. (Sr,Ba)Nb2O6 films of good crystallinity were formed on sapphire and alumina substrates by magnetron sputtering. The processes of recrystallization of films on single- and polycrystalline substrates under the conditions of ex situ annealing at temperatures of 1100–1200 °C were studied. Highly (00l) oriented films on sapphire substrate were obtained by the deposition in oxygen atmosphere at a substrate temperature of 900 °C with post-growth annealing in air at an annealing temperature of 1150 °C.

Preparation and Keep-Refreshing Effect of Chitosan/Sea Buckthorn Polysaccharide Composite Film on the Preservation of Yellow Cherry Tomatoes.

In this study, sea buckthorn polysaccharides (SBP) were added as functional substances to chitosan (CS), and chitosan/sea buckthorn polysaccharide (SCS) composite films were prepared using the casting method. The effects of SBP addition on the optical properties, physical properties, mechanical properties, structure, antioxidant activity, and antibacterial activity of the SCS composite films were studied, and the prepared SCS composite films were used to preserve yellow cherry tomatoes. The results showed that SCS composite films exhibited good UV resistance, water solubility, and antioxidant activity, but its apparent structure, hydrophobicity, and mechanical properties needed further improvement. Meanwhile, SBP has inhibitory effects on all 8 experimental strains. In addition, the SCS composite film with the addition of 200 mg/L SBP could reduce the weight loss rate of yellow cherry tomatoes, maintain hardness, delay the decrease of total soluble solids, titratable acid, and Vitamin C content, and inhibit the accumulation of malondialdehyde. SCS composite films are beneficial for enhancing the quality of yellow cherry tomatoes during storage, and their application in fruit and vegetable preservation has development prospects.