Oxide Film Thickness Research Articles

Amorphous Mixed-Vanadium-Tungsten Oxide Films as Optically Passive Ion Storage Materials for Solid-State Near-Infrared Electrochromic Devices.

Near infrared (NIR) electrochromic (EC) devices that selectively modulate the NIR light without affecting the daylight represent a promising window technology for saving energy consumption of buildings. Current research efforts have been focused on developing NIR-EC materials, while little attention has been directed to the optically passive ion storage materials that are crucial for balancing charges in a full NIR-EC device. Herein, we report that amorphous phase mixed-vanadium-tungsten oxide films exhibit minimum optical change with high ion storage capacity, which enables the usage of the mixed-metal oxides as optically passive counter electrode materials for NIR-EC devices. The mixed-vanadium-tungsten oxide films are synthesized by a room-temperature solution-based photodeposition method that allows us to precisely engineer the metal compositions and thicknesses of the mixed-metal oxide films, thus optimizing their optical inertness and ion storage capability. A solid-state NIR-EC device assembled with the mixed-vanadium-tungsten oxide film as an ion storage layer and the amorphous tungsten oxide hydrate as the NIR-EC layer shows fast response speed with cycling stability up to 10,000 cycles, proving the outstanding charge balancing capability of mixed-metal oxide. Our work provides an efficient strategy for developing optically passive ion storage films with high ion storage capability for high-performance EC devices.

XPS study of the thermal stability of passivated NiCrFeCoMo multi‐principal element alloy surfaces

X‐ray photoelectron spectroscopy analysis was applied to investigate the thermal stability under ultra‐high vacuum environment of the surface oxide film formed by electrochemical passivation of a newly designed Cr15Fe10Co5Ni60Mo10 (at.%) multi‐principal element alloy and providing the alloy superior localized corrosion resistance compared to conventional stainless steels and alloys. A spectral decomposition methodology involving the subtraction of Auger peaks overlapping the Fe 2p and Co 2p core level regions was applied for quantification of the oxide film composition and thickness. The results show that, at 100°C, the passive oxide film is mainly dehydrated and dehydroxylated. Obvious loss of Ni hydroxide and conversion of Mo (VI) to Mo (IV) species are observed at 200°C, with further reduction of Mo species to Mo (III) observed at 300°C. In this temperature range, the total cation quantity in the oxide film remains stable despite the compositional alteration. At 400°C, Cr (III) oxide forms at the expense of Fe and Mo oxides, resulting in an oxide film essentially consisting of chromium oxide. At 500°C, Cr (III) oxide is eliminated, making the passive film unstable at this temperature. Possible Cr oxide removal mechanisms are discussed.

Fabrication of Aluminum Oxide Thin-Film Devices Based on Atomic Layer Deposition and Pulsed Discrete Feed Method

This study demonstrates the low-temperature (<100 °C) process for growing a thin silica buffer layer and aluminum oxide by atomic layer deposition (ALD) in the same reaction chamber. Heterogeneous multilayer thin films are prepared by a dual-mode equipment based on atomic layer deposition and plasma-enhanced chemical vapor deposition (PECVD) techniques. The pulse discrete feeding method (DFM) was used to divide the precursor purging steps into smaller intervals and generate discrete feeds, which improved the saturated distribution of gas precursors, film density and deposition selectivity. The experimental results show that the process method produces a uniform microstructure and that the best film uniformity is ±2.3% and growth rate is 0.69 Å/cycle. The thickness of aluminum oxide film has a linear relationship with the cyclic growth number from 360 to 1800 cycles. Meanwhile, the structural and mechanical stress properties of aluminum oxide thin films were also verified to meet the requirements of advanced thin-film devices.

Effect of Ni and Fe elements on microstructure and high temperature oxidation behavior of laser cladding aluminum bronze coating

In this work, two kinds of aluminum-bronze coatings were successfully prepared on 316 stainless steel substrate by laser cladding technology. The changes of microstructure and high temperature oxidation behavior of pure aluminum bronze laser cladding layer before and after adding Ni and Fe elements were studied and compared. The results show that a certain amount of κ phase and Fe–Cr phase are constituted in the modified coating with the addition of Ni and Fe elements, which refines the structure and grains. The main components of the oxide layer of the two coatings are Al2O3. In the high temperature oxidation process, both two coatings experienced the formation, spallation, and recovery of an oxide film. The time to form a stable oxide film on the surface of the modified coating is significantly shorter than that of the original coating. As a result of the formation of fine and dense oxide particles on the modified coating's surface, the stability and internal stress resistance of the oxide film is superior. Under the condition of 1000 °C oxidation for 100 h, the oxidation film thickness and oxidation rate constant (kp) of the modified coating are about 0.88 and 0.79 times of that of the original coating. The addition of Ni and Fe can greatly enhance the laser cladding aluminum bronze coating's resistance to high-temperature oxidation.

Controlling the thickness and composition of stainless steel surface oxide film for anodic sulfide removal

Hydrogen sulfide is hazardous and toxic, and is present at many waste streams of industry processes. Anodic sulfide oxidation is a potentially effective approach to remove sulfide in aqueous media. This study therefore prepared and optimized surface oxide film on AISI 304 stainless steel (SS) as active and stable anode for sulfide removal. Among stainless steel samples of different anodization pretreatment duration, the anode with 15 min pretreatment (SS-15) resulted in the best sulfide removal at the same testing conditions, and achieved 48% and 18% improvement in terms of sulfide removal efficiency compared with the untreated SS and graphite, respectively. ANOVA-based tests (overall and for pairwise comparisons) also suggest the data are indeed valid. When anode potential was set no more than 1.62 V vs. reversible hydrogen electrode (RHE), direct sulfide oxidation dominated; and further increase in anode potential would initiate oxygen evolution reaction (OER) which contributed to indirect sulfide oxidation. Surface characterization found that the varying corrosion pretreatment duration led to oxide films of different thickness and chemical composition. The pretreatment duration from 15 min to 90 min increased the oxide film thickness from 178 nm to 264 nm and decreased the composition of FeOOH and NiOOH, which were most likely the catalytic active species for sulfide oxidation revealed by high-resolution XPS. Electrochemical analysis confirmed that the smaller thickness and enriched FeOOH/NiOOH composition in SS-15 led to a lower charge transfer resistance, a lower mass transfer resistance, and meanwhile a greater material stability. Depth profiling via high-resolution XPS identified metallic Fe inside oxide films and its presence may also promote the conductivity of the oxide film. This study demonstrated that anodization pretreatment of stainless steel was able to prepare effective and stable anode for electrochemical sulfide removal by controlling the thickness and composition of oxide films.

Potential dependent mechanism of the composition and electrochemical property of oxide films of Ti-6Al-3Nb-2Zr-1Mo

Potential dependent mechanism of the composition and electrochemical properties of oxide films formed on Ti-6Al-3Nb-2Zr-1Mo in 0.5 M H2SO4 at potential ranging within −0.80–5.00 V was studied. The quantitative calculation and qualitative analysis of thicknesses of oxide films and valence states of Ti and Al, Nb, Mo increase with potential increasing to 3.00 V, whereas surface roughness illustrates the opposite trend. The corrosion resistances and semiconductor properties results indicate better protection effect and uniformity of oxide film at higher potential in passive region. A schematic considering alloying elements effect within oxide films formed at different applied potential on Ti-6Al-3Nb-2Zr-1Mo is established.

ОКСИДНЫЕ ПЛЕНКИ С РАЗЛИЧНЫМИ ХАРАКТЕРИСТИКАМИ ПРОПУСКАНИЯ И ПОГЛОЩЕНИЯ В УФ-ОБЛАСТИ, ПОЛУЧЕННЫЕ ЭКСТРАКЦИОННО-ПИРОЛИТИЧЕСКИМ МЕТОДОМ

UV and visible transparency of ZrO2, CuO, TiO2, Y2O3, ZnO and NiO oxide films of various thickness obtained by the extraction-pyrolytic method on fused silica supports at pyrolysis temperature 500°C and crystallization temperature 700°C. The characterization of their optical performances demonstrated a possibility for obtaining coatings providing either reduction of increase of the transmission in different UV regions.

Direct bonding of Ni nanoparticles to a semiconductor Al electrode in air and its form

This research group evaluated the bondability of sinter bonding using Ni nanoparticles, which have a high melting point and excellent corrosion resistance, as a new metal nanoparticle bonding material, and found that bonding is possible at bonding temperatures below 400 °C when the particle size is less than 100 nm. Furthermore it was found that Ni nanoparticles can be directly bonded to Al, which is considered difficult to bond directly with solder materials containing tin (Sn) or lead (Pb), and that high bonding strength can be obtained. In addition, the bonding strength of Ni nanoparticles to Al was higher when bonded in air than in a reduction atmosphere of N2+H2 (3 %), indicating that there were differences in bonding properties depending on the bonding atmosphere. In this study, we compared the bonding properties to Al in different bonding atmospheres. In the N2+H2 (3 %) reducing atmosphere, the bonding strength was not increased even when the bonding temperature was increased. On the other hand, the bonding strength was significantly increased with increasing bonding temperature over 330 °C in air. The failure mode was also rupture in the bonding layer, and good bonding was achieved at the Ni/Al bonding interface. Observation of the bonding interface between Ni nanoparticles and Al using Transmission electron microscope (TEM) showed the presence of an interlayer of oxide film at both bonding interfaces in air and in the N2+H2 (3 %) reduction atmosphere. And the oxide layer at the interface bonded in air was thicker, indicating that the structure at the interface between the Ni layer, the oxide layer and the Al layer has changed. It was suggested that the difference in oxide film formation behavior, structure, and thickness affects the bondability due to the difference in the bonding atmosphere.

Exploitation of PANI based Metal Oxide (ZnO-SnO2) Thick Films Humidity Sensor1

Polyaniline (PANI) based Metal oxide nanocomposite thick films were prepared by using the screen printing technique. The films were fired and optimized temperature of 60ºc for 30 minutes in an air atmosphere. In the present work, Polyaniline is prepared by polymerization of aniline under acidic conditions. Zinc Oxide (ZnO) nanoparticles and Tin Oxide (SnO2) prepared by the Precipitation method at room temperature. The films were showing a decrease in resistance with an increase in temperature indicating semiconducting behavior. It is observed that PANI doped Metal oxide nanocomposite sensor shows a high response and sensitivity with good repeatability as compared to that of pure PANI and Metal oxide nanoparticle. The crystallinity and the crystallite size were examined by X-Ray Diffraction technique (XRD), and Scanning Electron Microscopy (SEM). Also confirms that the properties of pure polyaniline can be improved by the synthesis of Polyaniline - Metal oxide nanocomposites

Optical and structural properties of CdS-ZnO thick film

In the present work, we report the fabrication and characterization of undoped ZnO and Cadmium Sulfide (CdS) and Zinc Oxide (ZnO) thick films. The structural properties of ZnO films are characterized by X-ray Diffraction (XRD). It is evident from XRD that, the crystallite size of fabricated ZnO and CdS-ZnO films are 45 nm and 38 nm respectively. Optical properties have been investigated by U-V absorption. It is observed from U-V Spectroscopy that the band gap decreases with CdS doping. We found that all deposited ZnO thin films are to be polycrystalline structures of wurtzite, and the crystallite size of ZnO is in the nanometric range which further decreases with CdS doping.

Corrosion characterization of NiTi alloy by femtosecond laser surface processing

AbstractThe study of the corrosion resistance of NiTi alloy surfaces with different wettabilities is important to achieve improvements in biocompatibility. In this study, a femtosecond laser was used to process different wettability surfaces on the NiTi alloy. The corrosion resistance of the surfaces was examined via potentiodynamic polarization and electrochemical impedance spectroscopy. Scanning electron microscopy and X‐ray photoelectron spectroscopy were used to analyze the morphology and chemical composition of the surfaces. The findings demonstrate that when an original oxide film is destroyed by femtosecond laser processing with a low laser fluence, hydrophilic or hydrophobic surfaces are more vulnerable to erosion. The corrosion resistance of superhydrophilic surfaces is improved to a certain extent, whereas superhydrophobic surfaces exhibit excellent corrosion resistance. Superhydrophilic surfaces are protected from further corrosion by the formation of a dense oxide film after corrosion, whereas superhydrophobic surfaces can inhibit corrosion because of their thicker oxide film and additional air film produced by air trapped in the micro/nanostructure.

Investigation on the corrosion behavior of Alloy 800H at various levels of deformation

The corrosion behavior of Alloy 800H in deaerated supercritical water was investigated. Multi-pass cold rolling was used to achieve thickness reductions of up to 80%, and the weight gain vs. time (up to 1000 h) in supercritical water at 600 ℃ and 25 MPa were obtained for specimens in the polished vs. ground surface condition. Polished specimens without rolling showed the highest corrosion rates, and surface grinding or cold rolling significantly increased the corrosion resistance. A thick oxide film develops, with an outer moderately uniform layer of magnetite (Fe3O4) with crystallites along the surface, and areas of uneven oxidation into the metal that incorporate Cr (e.g., FeCr2O4). Very few Cr2O3 particles exist, and preferentially near the grain boundaries. Continuous Cr-rich oxide films were found in the thin oxide films on the surface of ground specimens and heavily rolled specimens, and an associated Cr depleted zone in the metal under the oxide of ground specimens, but not in heavily rolled specimens. This indicates that the high density of dislocations accelerates the diffusion of elements and enhance the formation of Cr-rich oxide film, which promotes passivity.

Effects of Zn injection on corrosion behavior and crud deposition of FeCrAl fuel cladding under subcooled nuclear boiling condition in high-temperature pressurized water

The effects of Zn injection on corrosion behavior and crud deposition of FeCrAl fuel cladding in high-temperature pressurized water were investigated under subcooled nuclear boiling condition. The crud deposition and the growth of double-layered oxide films under the crud occurred simultaneously. Zn injection decreased the oxide films thickness and reduced the quantity/size of the outer oxide particles. These effects changed the surface roughness and wettability of the oxide films, resulting in a reduction of deposited crud at the initial stage. Both Zn and released matrix elements could be incorporated into the crud and Zn reduced the size of crud particles.

Corrosion evolution of high-temperature formed oxide film on pure Sn solder substrate

The evolution of morphology, composition, thickness and corrosion resistance of the oxide film on pure Sn solder substrate submitted to high-temperature aging in 150 °C dry atmosphere was investigated. The results indicate that high-temperature aging accelerates the dehydration of Sn(OH)4 in the pre-existing native oxide film to form SnO2 and facilitates the oxidation of fresh Sn substrate, resulting in the gradual increase in oxide film thickness and surface roughness with prolonging aging time. However, the corrosion resistance of the film initially is enhanced and then deteriorated with an extending aging time. Besides, the formation and evolution mechanisms of the oxide film with aging time were discussed.

Probing the Effects of Electrode Composition and Morphology on the Effectiveness of Silicon Oxide Overlayers to Enhance Selective Oxygen Evolution in the Presence of Chloride Ions.

Seawater electrolysis offers significant logistical advantages over freshwater electrolysis but suffers from a fundamental selectivity problem at the anode. To prevent the evolution of toxic chlorine alongside the evolution of oxygen, a promising approach is the use of electrochemically inert overlayers. Such thin films can exert a perm-selective effect, allowing the transport of water and oxygen between the bulk electrolyte and the electrocatalytic buried interface while suppressing the transport of chloride ions. In this work, we investigate thin (5-20 nm) overlayer films composed of amorphous silicon oxide (SiO x ) and their application to suppressing the chlorine evolution reaction (CER) in favor of the oxygen evolution reaction (OER) during acidic saltwater electrolysis on three different types of electrodes. While SiO x overlayers are seen to be an effective barrier against the CER on well-defined, smooth Pt thin films, decreasing the CER activity roughly 20-fold, this ability has not been previously explored on Ir-based catalysts with a higher surface area relevant to industrial applications. On amorphous iridium oxide electrodes, the selectivity toward the CER versus the OER was marginally reduced from ∼98 to ∼94%, which was attributed to the higher abundance of defects in overlayers deposited on the rougher electrode. On the other hand, Ir-based anodes consisting of thick mixed metal oxide films supported on Ti showed a significant decrease in CER selectivity, from ∼100 to ∼50%, although this came at the cost of reduced activity toward the OER. These results show that the morphology and composition of the underlying electrode play important roles in the effectiveness of the selective overlayers and provide guidance for further development of high-surface-area OER-selective anodes.

Study on corrosion behavior of two superalloys under two extreme atmospheres

Inconel 617 and Hastelloy X alloys are two candidate materials for very high temperature gas-cooled reactor (VHTR) intermediate heat exchanger and steam generator equipment. This work explored the corrosion behavior of two alloys in the atmosphere of extreme air ingress accidents and vacuum environment. After the experiment, the corrosion behaviors of the two alloys were characterized and analyzed by electronic balance, scanning electron microscope(SEM), energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD) and carbon sulfur analyzer. The results showed that the mass change and oxide film thickness of Hastelloy X alloy and Inconel 617 alloy after corrosion in air met the oxidation parabola law, and the kp of Hastelloy is lower. The chromium migration of the two alloys was obvious after corrosion in air. The longer the corrosion time was, the more obvious the phenomenon was. The carbon content of the alloy did not change significantly with the corrosion time. Mass loss and decarburization occurred in both alloys after corrosion in vacuum, and volatile elements volatilized and migrated. The weight loss, decarburization and element volatilization of Hastelloy X were more obvious.

Micro/nano dual-scale porous surface structure of the Al alloys and improvement on the joint strength with carbon fiber reinforced PA 6 thermoplastic

Improving the interfacial bonding strength of the Al/CFRTP hybrid composites is beneficial for its application in lightweight automotive technology. This study fabricated the micro/nano dual-scale porous surface structures of the Al alloy by the low-cost and effective oxalic acid anodizing to improve the interlocking interface structure. The effects of current density and oxidation time of the anodic oxidation on the shear strength of the Al/PA 6 CFRTP hybrid composite joints were investigated. The results showed that with the increase of the oxidation current density and time, the nanopore diameter, porosity, wettability, and oxide film thickness were significantly improved. The shear strength of the Al/CFRTP PA 6 joints was as high as 23.7 MPa. The micro-scale pits (average size 6 μm) produced by the NaOH treatment and the nano-scale porous structure (16–106 nm) induced by anodizing enhanced the adhesion area and anchoring effect between the Al alloy and PA 6 resin. Thus, the synergistic improvement in the interfacial bonding strength was exhibited.

Enhanced stability and mobility of solution-processed oxide thin-film transistors with bilayer terbium-incorporated indium oxide channel

The trade-off between mobility and stability in oxide thin-film transistors (TFTs) hinders further advances of an active-matrix flat panel display. Herein, a solution-processed bilayer active channel is designed to improve the stability and mobility simultaneously. The optical bandgap and work function of Tb:In2O3 films are modulated by tuning the film thickness and Tb concentration of Tb-doped indium oxide (Tb:In2O3) films. Large conduction band offset is achieved in a Tb:In2O3 bilayer channel, which induces accumulation of abundant electrons at the interface. The mobility is significantly improved to 38.2 cm2/V s, and the photoinduced stability of bilayer Tb:In2O3 TFTs is improved with low threshold voltage shift of 0.26 and −0.38 V under negative-bias illumination stress and negative-bias temperature illumination stress, respectively.

(Industrial Electrochemistry and Electrochemical Engineering Division H. H. Dow Memorial Student Achievement Award) Electrochemically Grown Highly Textured Thick Ceramic Oxide Films for Energy Storage: A New Manufacturing Paradigm for Cathode Materials

Electrochemical synthesis of materials has contributed to significant breakthroughs in materials processing by replacing high temperature, cost and energy intensive pyrometallurgical processes. Noteworthy examples include aluminum extraction by Hall–Heroult process, electrowinning of copper, titanium extraction through the Kroll process, electrolytic production of steel, and electrochemical synthesis of cement. Increasing the energy and power density of alkali ion intercalated transition metal oxide cathodes which power electric cars and portable electronics, has been a growing topic of global techno-economic interest. Our work demonstrates a direct electrodeposition of thick ternary ceramic oxide films as an alternate scalable manufacturing technique for fabrication of binder-and-additive free cathode materials for secondary battery. Employing an intermediate temperature (200-400°C) molten hydroxide-based electrodeposition method, a general electrochemical growth strategy for multiple Li and Na ion cathode chemistries is demonstrated for the first time including NaCoO2, NaMnO2, LiCoO2, Li2MnO3, LiMnO2, LiMn2O4, (A. Patra, P.V. Braun et. al, PNAS, 2021) in a thick (> 50 µm) thick film form factor. In-plane and through-plane texture can be electrochemically architectured in LiCoO2 and NaCoO2 films across multiple textures: <003>||ND (Li/Na ion blocking sites parallel to the normal direction), <101>||ND, <104>||ND, <110>||ND (fast lithium ion conducting sites parallel to the normal direction). An accurate control of crystallization dynamics leads to highly anisotropic, grain boundary engineered structure with low tortuosity and fastest electron and Li ion conducting pathways (<110>||ND) oriented normal to the current collector. The highly textured (<110>||ND), dense (>95%) electroplated cathodes can perform even at ultrahigh thickness of ~ 200 µm (areal capacity of ~13.6 mAh/cm2) in comparison to 40-60 µm for conventional slurry cast cathodes (areal capacity of ~3-4 mAh/cm2 with a porosity of ~10-20%), a fivefold increase in areal capacity and volumetric energy density (A. Patra, P.V. Braun et. al, to be submitted). In order to enable a high voltage (> 4.5 V vs. Li) cathode design, a functionally graded architecture is also demonstrated with a core capable of providing high-capacity and rate capability (LCO <110>||ND); and multiple capping layers (LCO <003>||ND and Li2MnO3) to suppress harmful side reactions occurring at voltages beyond the normal operation range (beyond 4.2 V vs. Li). Our work paves the way towards an electrosynthesis platform for functional oxides with the ability to generate micron scale ordering with controllable in-and-through-plane orientation in thick ceramic oxide films important for electrochemical energy storage.

Combining High-Temperature Cyclic Voltammetry and Electrochemical Impedance Spectroscopy in a Setup for the Controlled Oxidation of Copper

Copper is utilized in a variety of industrial applications (e.g. heat conductors, electronic components, protective coating), where it is frequently exposed to high temperatures [1]. However, contact with the atmosphere at these high temperatures causes uncontrolled oxidation of the metal. Previous research investigated the oxidation mechanism by oxidizing at specific temperatures and then analyzing the oxide layers with a scanning electron microscope [2].This work presents a new method for the simultaneous investigation of the oxide layer formation by electrochemical impedance spectroscopy and cyclic voltammetry. The high-temperature electrochemical polarization method allows a dynamic adjustment of the oxygen partial pressure on the surface of the copper, leading to oxide layers with different compositions in respect to their thickness and defect density. The common combination of a potentiostat and a frequency response analyzer (FRA) in a three-electrode setup suffers from bandwidth limitations and artifacts [3]. Therefore, a novel method developed by Fafilek in 2009 [3] for a potential controlled electrochemical spectroscopy was adapted to our high-temperature oxidation setup. Thereby the two measuring units, potentiostat and FRA are electrically separated with regard to their grounding. Cyclic voltammograms are obtained as the result of the polarization of a sputtered copper ring versus a reference electrode, while the impedance spectra are recorded between the same copper ring (large contact area) and a copper sphere (small contact area) as shown in Figure 1. The FRA has nearly no internal resistance which ensures that both samples are adopting the same potential during the potential sweep resulting in an equal oxide formation on them. As the copper ring shows a significantly larger area than the copper sphere, the current received by the potential sweep is assumed to stem from the copper ring. Conversely, it is considered that the impedance spectra originate from the copper sphere, since the impedance of the copper ring can be neglected due to its large size. The data obtained from the potential sweep, such as the oxide structure and film thickness, are combined with the electrical properties acquired by impedance spectroscopy. This allows accurate characterization of the oxide layer that forms during electrochemically controlled oxidation.[1] Davis, J.R. ed., 2001. Copper and copper alloys. ASM international.[2] Zhu, Y., Mimura, K. and Isshiki, M., 2002. Oxidation mechanism of copper at 623-1073 K. Materials transactions, 43(9), pp.2173-2176.[3] Fafilek, G., 2009. A novel experimental method for potential controlled electrochemical impedance spectroscopy. Monatshefte für Chemie-Chemical Monthly, 140(9), pp.1121-1127. Figure 1