Structure Of Oxide Films Research Articles

Light and Carrier Transportation Management in Transparent Electrode for Achieving over 30% Efficiency Perovskite/Silicon Tandem Solar Cells.

Perovskite/silicon tandem solar cells have drawn widespread attention owing to their higher power conversion efficiency (PCE). However, reducing the reflection and parasitic absorption as much as possible in the transparent electrode is of considerable interest to promote the tandem device to obtain higher circuit current density (JSC). Furthermore, the carrier vertical and lateral transport capability of transparent electrodes also affects the electrical performance of solar cells. Herein, we designed and realized a stacked structure of a columnar-equiaxed zirconium-doped indium oxide (IZrO) film. The optimal stacked IZrO thin film shows carrier density and mobility of 9.4 × 1020 cm-3 and 29.7 cm2 V-1 s-1, respectively. Additionally, it also shows superior optical transmittance and lower parasitic absorption in the visible-to-near-infrared region. In addition, reflectance in the perovskite/c-Si tandem solar cell shows an obvious reduction after the application of a stacked IZrO transparent electrode because of the gradient refractive index. Finally, the stacked IZrO transparent electrode was incorporated into P-I-N-type perovskite/textured-silicon tandem solar cells, and the champion stacked IZrO-based device showed PCE of 30.12% with an active area of 1.05 cm2.

(Invited) Mild Anodization of Aluminum: From Fundamentals to Industrial Applications

Considering the recent energy crisis and global environmental pollution, the weight reduction of vehicles through the modification of several parts (e.g., engines and wheels) is emerging as an important research area. One strategy for achieving this is the use of aluminum. Aluminum, a lightweight material with excellent recyclability, is widely used in various industrial fields. There are various surface treatment methods for aluminum, depending on the purpose of use in each operating environment. Corrosion resistance and hardness of native oxides are not enough under some environment.To improve the surface properties of aluminum, anodic oxidation of aluminum (so-called anodizing or anodization), is generally applied. The surface treatment has a history of nearly 100 years. In Japan, anodization using oxalic acid was first patented in 1923. A porous-type oxide film formed on aluminum by anodization, or a product covered with the porous alumina film, is industrially called alumite in Japan. The structure of a porous-type oxide film (alumite) determines the various surface properties of aluminum. For instance, to increase the hardness of anodic films on aluminum, the anodization is industrially carried out at low temperature to avoid chemical dissolution of the formed oxide film during anodization.Here, I present an overview of the progress of anodization in common acidic electrolytes (e.g., sulfuric acid, oxalic acid, or phosphoric acid) containing alcohol as an additive [1-6]. Anodization was mainly conducted using various alcohols with different physical properties under mild anodization conditions with a constant current of 100 A·m−2 at 20 °C. The effects of alcohol addition in electrolytes on the anodization behavior of aluminum, the coating ratio, the porosity, the maximum attainable film thickness, and the hardness of anodic films will be discussed in terms of both basic research and commercial applications. H. Asoh, M. Matsumoto, H. Hashimoto, Surf. Coat. Technol., 378, 124947 (2019).M. Matsumoto, H. Hashimoto, H. Asoh, J. Electrochem. Soc., 167, 041504 (2020).H. Asoh, T. Sano, J. Electrochem. Soc., 168, 103506 (2021).H. Asoh, H. Kadokura, R. Murohashi, M. Matsumoto, J. Electrochem. Soc., 169, 073510 (2022).T. Sano, Y. Wakabayashi, H. Asoh, Surf. Coat. Technol., 459, 129399 (2023).H. Asoh, S. Ota, K. Hagiwara, J. Electrochem. Soc., 171, 033502 (2024).

Corrosion Ferritic Stainless Steel in a Simulated Hydrothermal Liquefaction Bioconversion Aqueous Solution: Effect of Surface Cr Content

Abstract The objective of this study was to determine the effect of surface Cr content on the corrosion of ferritic stainless steels in hot pressurized alkaline water (310 °C at 10 MPa) simulating a hydrothermal liquefaction bioconversion medium. Two methods to increase the Cr surface content were investigated: (i) selecting commercial grades of ferritic stainless steel with an increasing Cr content and (ii) applying a Cr coating (chromizing) to a low-Cr (Type 409) ferritic stainless steel. The observed parabolic-like corrosion kinetics were analyzed and discussed in terms of the structure and composition of the double layered oxide films that formed. The (surface) Cr content is a critical factor affecting corrosion. Corrosion was reduced by 66% (after 20 days exposure) when increasing the Cr content from 9 wt.% (P91) to 21 wt.% (SS443) in the commercial grades of ferritic stainless steel. Moreover, corrosion was reduced by 84% (after 20 days exposure) by chromizing the surface of a low-Cr (Type 409) ferritic stainless steel. Improved corrosion protection was attributed to increased Cr incorporation into the inner (barrier) Fe(Fe1-nCrn)2O4 layer, with the formation of a Cr2O3 layer (resulting from chromizing) being most beneficial.

Effect of passivation behavior of SAC305 alloy on the structure and defects of surface oxide film

The effect of the passivation behavior of SAC305 alloy in deionized water on the structure and defects of the surface oxide film was investigated. The results indicate that during the passivation process of the alloy film formation, as the surface potential increases, Sn is oxidized, undergoing two transformations: first to Sn(II) and then to Sn(IV). During this process, the point defects in the oxide film evolve from Sn(II) interstitial ions and O vacancies to Sn(II) ion vacancies, and subsequently to Sn(II) and Sn(IV) interstitial ions and O vacancies. Additionally, the oxide film does not cover the Ag3Sn phase, yet the alloy is able to maintain an effective passivation.

Effect of oxidation temperature on surface oxide film structure and corrosion resistance of 50 steel

The phase structure, thickness and corrosion resistance of oxidation film of 50 steel oxidized at 200∼600 °C in an air furnace were studied by AES, SEM, XRD and EIS in this paper. The results show that the concentration of surface oxygen atoms of 50 steel shows a trend of rapidly increasing to a peak, maintaining stability for a distance, then decreasing, and finally stabilizing after oxidation treatment at different temperatures. The peak concentration of oxygen atoms and the stabilization distance are found to vary with the oxidation temperature. The oxidation activation energy is 25.2 kJ/mol. With the increase of oxidation temperature, the oxide film composed of the outer Fe2O3 layer and the inner Fe3O4 layer is generated on the surface of 50 steel, and Fe2O3 is the primary constituent. Moreover, the corrosion of oxide film in NaCl solution is marked by anodic activation dissolution. The thermal oxidation samples demonstrate better corrosion resistance than the original samples with the increase of oxidation temperature, there is an upward trend in the self-corrosion potential, whereas a decreasing trend in the corrosion current density, and the capacitor-reactance arc radius is gradually increased. The maximum corrosion potential, the minimum corrosion current density and the largest capacitor-reactance arc radius are recorded at 600 °C, at which temperature it has the best corrosion resistance.

Effect of Cr content on the high temperature oxidation behavior of FeCoNiMnCrx porous high-entropy alloys

FeCoNiMnCr porous high-entropy alloys were prepared using the activation reaction sintering method with Fe, Co, Ni, Mn, and Cr as raw materials. The oxidation behaviors of FeCoNiMnCrx porous high-entropy alloys with different Cr contents, such as pore structure, the surface oxide film phase composition, structure, and morphology, were characterized by X-ray diffraction (XRD), electron probe micro analysis (EPMA), energy dispersive X-ray spectroscopy (EDS), and pore tester after high-temperature oxidation at 800–1000 °C. The results indicate that the initial porous high-entropy alloy comprises a single FCC solid solution phase. With the increase in Cr content, the average pore diameter, average porosity, and air permeability of the porous high-entropy alloy also increase. The oxidation kinetics of the porous high-entropy alloy after exposure to temperatures between 800 °C and 1000 °C follows a single-stage parabolic evolution law. At the same oxidation temperature, With the increase of Cr content, the oxidation gains gradually increased, at the same Cr content at different temperatures, the antioxidant performance of 1000 °C was the weakest, followed by 800 °C, and 900 °C showed excellent antioxidant performance. The oxidation products are mainly Mn2O3, Mn3O4, (Mn, Cr)3O4, Cr2O3and Fe2O3.

Atomistic insight into structure and properties of oxide films formed upon oxidation of Al–Mg alloys – reactive molecular dynamics study

Oxidation phenomena on metal surfaces can be advanced using atomistic modeling for the study of the structure and properties of the growing oxide films. Molecular dynamics investigations were performed to study thermal oxidation of single-crystal and polycrystalline Al–Mg alloys with low Mg content of up to 2.5 at. %. Structure, topological atom network and surface topography of the oxide films grown on Al–Mg surfaces at 300, 475 and 663 K are determined. Mg-content and temperature dependent oxide films developed on Al-Mg alloy substrates with two-phase oxide film formation as also confirmed experimentally. It is related with a gradual long-range order formation above 475 K for (Al,Mg)-oxide films, for which solid amorphous phase predominates over crystalline phase. The 1.12-nm-thick oxide films grown at 300 K are fully amorphous and build up from (Al, Mg)-oxide which the Al2O3 dominates. Increase of Mg coefficient confirms faster Mg diffusion to oxide/alloy interface at high oxidation temperature and the formation of MgO-like network. The presence of planar crystal defect (grain boundary, GB) into Al-Mg alloy substrate governs the kinetics of oxide film growth and its structure evolution. GB also compensate internal stresses during oxide film growth. Obtained results are in good agreement with experimental observations.

Fast inverse design of microwave and infrared Bi-stealth metamaterials based on equivalent circuit model

This work proposed a fast inverse design method for microwave and infrared (IR) bi-stealth metamaterials based on the equivalent circuit model (ECM). Using this method, we designed a microwave and IR bi-stealth metamaterial by deploying a multilayered structure of the indium tin oxide (ITO) film based metasurface. First, the IR emissivity of the ITO film was calculated in the framework of the ECM. Then, an ITO metasurface was proposed to implement low IR emission and high microwave transmission simultaneously. Based on the ECM of the square patch, the ECM of the whole metamaterial was established at the microwave band. An inverse design program was built by incorporating the ECM with genetic algorithm (GA). Structure parameters of the metamaterial were optimized by GA to achieve the broadest microwave stealth bandwidth for the given thickness. Finally, the sample of the optimized bi-stealth metamaterial was prepared and tested. The calculated, simulated, and measured results are in good agreement, showing that such a metamaterial has an IR emissivity of 0.18 in the band from 3 to 14 μm and an efficient microwave stealth band from 4.8 to 17 GHz with a thickness of 4.9 mm. The proposed method will benefit the design and application of microwave and IR bi-stealth metamaterials.

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.

Effect of polyacrylic acid on the corrosion behavior of Alloy 690 in pressurized water reactor secondary water

The effect of polyacrylic acid (PAA) on the corrosion behavior of Alloy 690 in simulated pressurized water reactor secondary water was investigated. The duplex oxide film structure, consisting of a Ni-rich outer layer and a Cr-rich inner layer, was maintained regardless of PAA presence. PAA inhibited the growth of outer Ni-rich particles while promoting Cr enrichment in the inner layer and inducing its amorphization, both enhancing oxidation resistance. However, excess PAA (≥ 500 ppb) suppressed protective oxide formation during initial oxidation, leading to oxygen penetration into the matrix. A PAA concentration of around 250 ppb is considered optimal for steam generators, as it provides the benefits of PAA without adverse effects on the alloy.

3D printing flexible Ga-doped ZnO films for wearable energy harvesting: thermoelectric and piezoelectric nanogenerators

The 3D printing of energy harvesters using earth-abundant and non-toxic elements promotes energy sustainability and market competitiveness. The semiconducting behavior and non-centrosymmetric wurtzite crystal structure of gallium-doped zinc oxide (GZO) films make them attractive for thermoelectric and piezoelectric nanogenerators. This study investigates the thermal, structural, mechanical, thermoelectric, and piezoelectric properties of 3D-printed GZO nanocomposite films. Thermal analysis demonstrates the stability of the nanocomposite film up to 230 °C, making it suitable for wearable energy harvesters. The crystalline structure of the nanocomposite film aligns with the hexagonal wurtzite structure of ZnO and displays a bulk-like microstructure with a uniform distribution of elements. The presence of Ga 2p, Zn 2p, O 1 s, and C 1 s core levels confirms the development of the nanocomposite film, characterized by a fine granular structure and a conductive domain compared to the neat resin film. The inclusion of GZO nanofillers tailors the stress–strain behavior of the nanocomposite film, enhancing flexibility. The 3D-printed GZO nanocomposite films demonstrate a promising thermoelectric power factor and piezoelectric power densities, along with mechanical flexibility and thermal stability. These advancements hold significant potential for wearable and hybrid energy generation technologies.

Effect of mass ratio on flame propagation behaviors and thermal radiation performance of Al–AlH3 composite dust

Aluminum (Al) is a high-energy density fuel additive commonly used in solid composite propellants. However, Al dust will form a dense oxide layer, which will reduce activity. Aluminum hydride (AlH3) can release hydrogen, destroying the oxide film structure and releasing more energy. In this paper, the flame and thermal radiation characteristics of Al–AlH3 composite dust explosion with different mass ratios were studied experimentally. The results indicate that under the same mass ratio, the propagation height, velocity, and flame surface temperature of the composite system show a trend of first increasing and then decreasing. With the decrease of Al, the propagation height, velocity, and flame surface temperature increase gradually, with maximum values of 420 mm, 17.9 m⋅s−1, and 2033 °C, respectively. With the increase of AlH3 content, the composite system releases more H2, which lead to the enhancement of reaction intensity. Based on experimental and semi-empirical static models, the heat radiation flux is calculated. Compared with the quasi-static process on the tube side, the experimental value of vertical heat flux is greater than the calculated value. Therefore, the model is modified by introducing λ. It provides a theoretical basis for the flame and thermal radiation of dust explosions confined by vertical tubes.

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.

Relationship between doped structure and properties of zinc oxide film

Overview of relevant research fields: Introduce the basic concepts and background of oxidizing thin films and doped materials. Discuss the characteristics, applications, and effects of doping on the performance of oxidizing thin films. Types and effects of doping elements: Introduce commonly used doping elements in oxidizing thin films, such as Al, Ga, Sn, etc. Discuss the effects of different doping elements on the properties of thin films, such as electrical, optical, and magnetic properties. Temperature and concentration effects: Exploring the effects of doping temperature and concentration on the properties of oxidizing thin films. Analyze the mechanisms and patterns of the effects of temperature and concentration on lattice structure, defect morphology, and carrier concentration. Application Fields and Prospects: Review the research progress of oxidative thin film doping in various application fields, such as optoelectronic devices, catalysts, sensors, etc. Looking forward to the future development direction and potential application fields of doping in oxidizing thin films. When writing a review, ensure accurate citation of relevant literature and analyze and discuss from multiple perspectives. In addition, pay attention to using concise and clear language to make it easy for readers to understand and obtain information. The most important thing is to ensure that the literature review complies with academic integrity and ethical standards, and adheres to citation norms.

Structure and optical properties of aluminum oxide films (Al2O3) after heating in water vapor and vacuum

Structure and optical properties of aluminum oxide films (Al2O3) after heating in water vapor and vacuum

Ionization Processes of Negative Corona Discharge Part 1. Review and Experiment

The purpose of the research is an experimental study of physical processes in the near-electrode zones of negative point electrodes in an electronegative gas (air) under the condition of a high-voltage field.Methods. Video image analysis, current-voltage characteristics measurements, and spectroscopy are used. The current-voltage characteristics of the corona discharge ignition voltage in the environment are measured, the problem of experimental identification of surface charges, the mechanism of negative corona discharge ignition, and the ionic structure of streamers is studied, degradation of electrodes during negative corona discharge, spectrum of corona discharge creation and electromagnetic sound.Results. It is shown that at small radii of curvature of needle electrodes, the development of a negative corona discharge is due to the cold emission of electrons, and on flat and slightly curved negative electrodes, due to the capture of surface electrons by electron-withdrawing molecules. The mechanism of ignition of a corona discharge in an electronegative gas with a negative needle, the structure of streamers from negative needles, the emission spectrum and ethonic degradation of electrodes have been studied.Conclusions. The ignition of a negative corona discharge at small radii of the tips of the pointed needles (ro less than tens of microns) is due to the cold emission of electrons followed by impact ionization of neutral molecules. With slightly curved electrodes, the appearance of a negative corona discharge is due to the capture of surface electrons by electronegative gas molecules with subsequent plasma-chemical reactions. The formation of surface electrons depends on many factors: the presence and structure of oxide films (roughness, defects, etc.), which determine the electron work function and form local fields at the tips of microtips. The appearance of a corona discharge leads to degradation of the corona electrodes, expressed in the spraying of the tips of the points and the melting of the needles. In the dark region of the negative corona discharge (U < U*), photons in the in the ultraviolet spectrum (UV spectrum) are emitted, and when U > U*, in addition to UV photons, photons in the visible region of the spectrum are emitted. Glow fluctuations are caused by the chaotic dynamics of the formation of injection centers (melted tubercles - ectons) on the surface of the corona electrode. The ignition of a corona discharge is accompanied by sound emission with a frequency of about 300 Hz.

Oxidation Behavior of Pre-Strained Polycrystalline Ni3Al-Based Superalloy.

The harsh service environment of aeroengine hot-end components requires superalloys possessing excellent antioxidant properties. This study investigated the effect of pre-strain on the oxidation behavior of polycrystalline Ni3Al-based superalloys. The growth behaviors of oxidation products were analyzed by scanning electron microscope, transmission electron microscope, X-ray Photoelectron Spectroscopy and Raman spectroscopy. The results indicated that the 5% pre-strained alloys exhibited lower mass gain, shallower oxidation depth and more compact oxide film structures compared to the original alloy. This is mainly attributed to the formation of rapid diffusion paths for Al atoms diffusing to the surface under 5% pre-strain, which promotes the faster formation of protective Al2O3 film while continuing to increase the pre-strain to 25% results in less protective transient oxidation behavior being aggravated due to the increase in dislocation density within the alloy, which prevents the timely formation of the protective Al2O3 film, resulting in uneven oxidation behavior on the alloy.

Interfacial carbon quantum dot thin film impacts on morphological and chemical structures of fluorine-doped tin oxide films

Morphology and chemical bonding states, including surface roughness, film density, F-doping, and oxygen vacancy (VO) concentration directly affect the electrical and optical properties of fluorine-doped tin oxide (FTO) films. In this study, morphology and chemical bonding states of FTO films are engineered simultaneously by introducing a carbon quantum dot (CQD) thin film as an interface layer during ultrasonic spray pyrolysis deposition. The abundant oxygen-containing surface functional groups and large surface free energy of the CQD thin film promoted (200) oriented crystal growth and accelerated nucleation of FTO, resulting in smooth and dense FTO film morphology. The abundant carboxyl surface functional groups on the CQDs generate active F− species that are effectively doped into SnO2. Formic acid, formed by dissociation of the carboxyl group, can serve as a strong reducing agent for extracting oxygen atoms from the SnO2 lattice, thereby increasing the VO concentration. The accelerated F-doping and VO concentration result in the generation of additional free electrons. The effects of the optimized CQD on the morphological and chemical structures of FTO films are demonstrated by their superior electrical (sheet resistance of ∼5.7 Ω/□) and optical properties (visible transmittance of ∼85.9 %) compared with bare FTO. Moreover, CQD/FTO used as transparent conducting electrodes in electrochromic (EC) application exhibited improved EC performances, including fast switching speeds (5.3 s and 2.3 s for bleaching and coloration, respectively) and high coloration efficiency (81.1 cm2/C) compared to that of bare FTO.

Tin oxide thin films on Ag(111): Thickness and temperature dependent study of surface structure and electronic properties

Growth and structure of tin oxide films on Ag(111) from submonolayer to 10 monolayer equivalent thickness have been studied using low energy electron diffraction (LEED), x-ray photoemission spectroscopy (XPS) and angle-resolved photoemission spectroscopy techniques for room temperature (RT) and high temperature (HT) (573 K). For RT growth, most of the tin is oxidised to form tin oxide (SnOx) as confirmed by XPS where no metallic component is noticed. However, the grown films are not epitaxial or ordered which can be confirmed by no spots in LEED for higher coverage. Metallic Sn along with two oxidation states of Sn are noticed for HT growth, with the surface mainly composed of SnO2. LEED pattern shows the presence of c(2 × 2) and (3 × 1) along with two different hexagonal multidomain type patterns. The electronic structure for lower coverage resembled the Sn/Ag(111) alloy structures for lower coverage. For higher coverages appearance of three bands below 2 eV binding energy was noticed.

High-performance a-Ga2O3 solar-blind photodetectors by pulsed magnetron sputtering deposition

Solar-blind photodetectors (SBPDs) based on the ultrawide-bandgap semiconductor Ga2O3 have gained attention due to their potential applications in both military and civilian domains. As technology advances, photodetectors are being improved to achieve better energy efficiency, smaller size, and better performance. Solar-blind photodetectors based on a metal-semiconductor-metal structure of amorphous gallium oxide (a-Ga2O3) films were fabricated by pulsed magnetron sputtering deposition (PSD). The photodetector based on amorphous gallium oxide has a responsivity of 71.52 A/W, a fast rising and falling response time of less than 200 ms, a photo-to-dark current ratio (PDCR) of 6.52 × 104, and an external quantum efficiency of 34 526.62%. PSD-prepared gallium oxide SBPDs demonstrate a cost-effective room temperature method for growing gallium oxide and show the advantages of growing gallium oxide.