Properties Of Oxide Layers Research Articles

Impact of Annealing in Various Atmospheres on Characteristics of Tin-Doped Indium Oxide Layers towards Thermoelectric Applications.

The aim of this work was to investigate the possibility of modifying the physical properties of indium tin oxide (ITO) layers by annealing them in different atmospheres and temperatures. Samples were annealed in vacuum, air, oxygen, nitrogen, carbon dioxide and a mixture of nitrogen with hydrogen (NHM) at temperatures from 200 °C to 400 °C. Annealing impact on the crystal structure, optical, electrical, thermal and thermoelectric properties was examined. It has been found from XRD measurements that for samples annealed in air, nitrogen and NHM at 400 °C, the In2O3/In4Sn3O12 share ratio decreased, resulting in a significant increase of the In4Sn3O12 phase. The annealing at the highest temperature in air and nitrogen resulted in larger grains and the mean grain size increase, while vacuum, NHM and carbon dioxide atmospheres caused the decrease in the mean grain size. The post-processing in vacuum and oxidizing atmospheres effected in a drop in optical bandgap and poor electrical properties. The carbon dioxide seems to be an optimal atmosphere to obtain good TE generator parameters-high ZT. The general conclusion is that annealing in different atmospheres allows for controlled changes in the structure and physical properties of ITO layers.

Copper Oxide Electrochemical Deposition to Create Antiviral and Antibacterial Nanocoatings.

The impact of the reaction environment on the formation of the polycrystalline layer and its biomedical (antimicrobial) applications were analyzed in detail. Copper oxide layers were synthesized using an electrodeposition technique, with varying additives influencing the morphology, thickness, and chemical composition. Scanning electron microscopy (SEM) images confirmed the successful formation of polyhedral structures. Unmodified samples (CuL) crystallized as a mixture of copper oxide (I) and (II), with a thickness of approximately 1.74 μm. The inclusion of the nonconductive polymer polyvinylpyrrolidone (PVP) during synthesis led to a regular and compact CuO-rich structure (CuL-PVP). Conversely, adding glucose resulted in forming a Cu2O-rich nanostructured layer (CuL-D(+)G). Both additives significantly reduced the sample thickness to 617 nm for CuL-PVP and 560 nm for CuL-D(+)G. The effectiveness of the synthesized copper oxide layers was demonstrated in their ability to significantly reduce the T4 phage titer by approximately 2.5-3 log. Notably, CuL-PVP and CuL-D(+)G showed a more substantial reduction in the MS2 phage titer, achieving about a 5-log decrease. In terms of antibacterial activity, CuL and CuL-PVP exhibited moderate efficacy against Escherichia coli, whereas CuL-D(+)G reduced the E. coli titer to undetectable levels. All samples induced similar reductions in Staphylococcus aureus titer. The study revealed differential susceptibilities, with Gram-negative bacteria being more vulnerable to CuL-D(+)G due to its unique composition and morphology. The antimicrobial properties were attributed to the redox cycling of Cu ions, which generate ROS, and the mechanical damage caused by nanostructured surfaces. A crucial finding was the impact of surface composition rather than surface morphology on antimicrobial efficacy. Samples with a dominant Cu2O composition exhibited potent antibacterial and antiviral properties, whereas CuO-rich materials showed predominantly enhanced antiviral activity. This research highlights the significance of phase composition in determining the antimicrobial properties of copper oxide layers synthesized through electrodeposition.

In-situ impedance spectroscopy on copper oxide scales under potential controlled oxidation at high temperatures

In recent years, copper oxide (Cu2O) has gained significant attention for its multifaceted role as a catalyst, photocatalyst and semiconductor. Possessing a p-type conductivity and a bandgap of 2.17 eV, Cu2O emerges as an ideal candidate for applications such as water splitting and photovoltaic cells. However, to utilize its full potential, an in-depth understanding of the electrical properties of Cu2O in terms of defect density and defect mobility is required. This knowledge forms the basis for the targeted production of oxides with precisely tuned electrical properties.Extensive research on thermal oxidation under varied conditions has been performed to clarify the mechanisms governing oxide formation and growth. However, the in-situ investigation of the electrical properties of the oxide layers during their formation process is challenging.This work introduces a new method for the controlled oxidation of copper, while concurrently offering an in-depth investigation of the electrical properties of these nanometer-thick oxide layers. The implemented arrangement of potentiostat and frequency response analyzer enables their artifact-free combination. Performing HT-CV measurements in a solid electrolyte cell-setup allows to control the (potential-dependent) oxygen pressure at the copper surface. Using HT-CV, the current represents the kinetics of the redox reactions and the electric charge corresponds to the amount of substance converted. In-situ electrochemical impedance data are used to determine the electrical properties of the controlled grown layers. As a result, the defect density is obtained as a function of the oxygen partial pressure.

UV photodetectors based on W-doped ZnO thin films

W-doped ZnO thin films deposited on Si substrates with (100) orientation by sol–gel spin coating method at temperature 500 °C. W/Zn atomic ratio varies from 0% to 4%. Then, the UV detection performance analysis of p–n heterojunction UV photodetectors based on W-doped ZnO/Si is analyzed. The current–voltage curves of W-doped ZnO/Si are investigated in dark and exhibit diode-like rectifying behavior. Among doped ZnO/Si, sample with atomic ratio of W/Zn = 2% is the best candidate to study photodetector characteristics in UV range. The resulting device exhibits a rectification ratio RR of 5587 at ±5 V, a higher responsivity of 3.84 A W−1 and a photosensitivity value of 34 at 365 nm under 0.5 mW cm−2. The experimental findings reveal that the UV detection performance of the heterojunction-based photodetectors strongly dependent on the properties of metal oxide layer. The main goal of this work is to investigate the effect of W doping on the performance of ZnO/Si based photodetectors. Based on our results, it is observed that 2 at% of W dopant is the optimum amount of doping for high performance photodetector of ZnO:W/Si heterojunction thanks to the suppressed recombination ratio and enhanced carrier separation properties in the depletion zone.

Ellipsometry of very thin Al2O3-HfO2 stacks for nano-memory applications

Nowadays, the way towards manufacturing of advanced flash memory devices with conformal layers in stacks or laminates depends on their physical characterisation, i.e. the layer and interface thicknesses, density and composition. The transition dimension between thin and very thin stacks is in the range of few nanometres. The assumption that the oxide layer properties in the very thin stacks are constant in depth or are the same as for the bulk material values is not correct. We have applied ellipsometry (Variable Angle Spectral Ellipsometry, and Multiple Angle Incident Ellipsometry) with appropriate algorithms for data interpretation to investigate very thin Al2O3/HfO2 stacks (5 bioxide blocks) grown by ALD with a total thickness below 20 nm. Depth profiling was used in simulations as a complimentary tool. A quantitative determination of HfO2 volume fraction in the stack depth was obtained. An independent determination of the thicknesses and the composition of blocks in the stacks were achieved. Lorenz-Lorentz mixing model was applied for the estimation of dielectric properties of the different layers in the stack depth.

Laser color marking of stainless steel – Investigation of the fluence-dependent and thermal mechanisms in generating laser induced surface modifications

Laser color marking is an attractive process to generate functional, aesthetic and durable colorations on various suitable metals such as stainless steel or titanium. The color generation is mainly based on interference effects on thin oxide layers, usually induced by nanosecond pulsed laser irradiation. Due to the large number of mutually influencing processing parameters and different thermal, chemical, structural and topological influences on the coloring results, the process is still not fully understood. Moreover, the reproducibility of the markings and the processing times often do not meet the requirements of industrial manufacturing processes. To improve the understanding of the underlying phenomena comparable colors are generated using different parameter sets. Spectroscopic, microscopic and SEM/EDS analyzes are carried out to investigate the effects of the surface topology, oxide layer properties, chemical composition and heat accumulation on the marking results.

Proton Permeable, Oxygen Blocking, Ultrathin Al2O3 Layers for Electrocatalytic Applications

Operating zero-gap electrolyzers at current densities above 1 Acm-2 is very challenging because ohmic losses associated with ion transport across the ion exchange membrane become predominant.[1] Technically, we can reach current densities up to 10 Acm-2. However, even a 100 micrometer thin nafion membrane would lead to cell voltages over 3 V [2] due to ohmic losses. Therefore, research and experimental development efforts are still needed to enable and increase the cell efficiency at elevated current densities.Implementing an ultrathin membrane of only a few nanometers in electrolyzers will minimize ion transport (i.e. protons) losses and will enable high-throughput electrolysis at low temperatures. However, to date, there is no concept available to perform electrochemical conversions using membranes of only of a few nanometers thickness that can block molecules but permeate protons.Multiple reports have demonstrated that dense ultrathin oxide layers, i.e. SiO2, can be used as electrocatalyst coatings to increase selectivities by blocking undesired ions/molecules from reaching the electrode.[3,4] The properties of such dense ultrathin oxide layers in principle fulfil the requirements of a proton exchange membrane, being only a couple of nanometer thin.To implement a nanometer thin proton exchange membrane into an electrolysis setup and enable mechanical integrity we envision a 3D-nanotube array design as shown in Figure 1a. In the ‘inside’ of the tube we perform the Hydrogen evolution reaction, and on the ‘outside’ the water oxidation reaction. Cathode and anode are separated only by a dense ultrathin oxide layer that permeates protons but blocks oxygen.Herein, we discuss the performance of ultrathin dense and amorphous Al2O3 layers made via pulsed laser deposition (2.5 nm, 3 nm, and 5 nm) with regard to proton and oxygen permeability. Electrochemical impedance spectroscopy allows us to determine diffusion coefficients and charge transfer resistances (Figure 1b). We use state-of-the-art operando FT-IR reflection-absorption spectroelectrochemistry that enables us to probe the dynamic structural and morphological changes of the dense alumina layer over time vs. applied potential (Figure 1c). In fact, we observe that proton permeation improves over time while we can exclude dissolution of the Al2O3 layer.

The effect of silica NPs incorporation on protective properties of oxide layers formed by PEO on Mg97Y2Zn1 alloy with LPSO-phase

The inherited chemical inhomogeneity in oxide layers obtained by plasma electrolytic oxidation (PEO) on the magnesium alloy Mg97Y2Zn1 is associated to long-period stacking-ordered (LPSO) phase present in the treated alloy. This heterogeneity results in decrease of corrosion resistance and adhesion strength. The problem was solved by adding silica nanoparticles (NPs) into the electrolyte under PEO. According to the model developed, NPs which are harder than the oxide layer and being electrically charged, can be accelerated by an electric field and penetrate deep into the layer. The near-surface incorporation of NPs results in branching of the local breakdowns of vapor-gas bubbles that leads to an increase of the volumes of oxide layer and improvement of its properties.

The Influence of Surface Preparation on Corrosion-Protection Properties of Oxide Layers Formed on MA8 Magnesium Alloy by Microarc Oxidation

The Influence of Surface Preparation on Corrosion-Protection Properties of Oxide Layers Formed on MA8 Magnesium Alloy by Microarc Oxidation

Modification of the structure and properties of oxide layers on aluminium alloys: A review

Abstract Aluminium alloys are a material that is increasingly used in industry. This is due to very good strength properties with low specific weight and low production costs. The disadvantage of kinematic system aluminium elements is their surface’s susceptibility to adhesive wear. One method of eliminating the adverse impact of adhesive tacks on the surfaces of cooperating aluminium components of machinery is the application of the method based on the anodic oxidation of alloys surface. The layers obtained by this method are widely used in sliding connections of kinematic machine parts. The modification of anodic oxide layers with admixtures has been an uninterrupted area of interest since the 1990s. This article is a review of selected methods of modifying the structure and properties of aluminium oxide layers on aluminium alloys.

Morphological and semiconductive properties of the anodic oxide layers made on Fe3Al alloy by anodizing in tartaric-sulfuric acid mixture

It has recently been found that the anodizing of FeAl alloys allows the formation of iron-aluminum oxide layers with interesting semiconducting properties. However, the lack of systematic research on different anodizing regimes is hampering their full exploitation in numerous photoelectrochemical-related applications. This study address, for the first time, the systematic effect of the electrolyte composition on the formation of self-ordered oxide films by anodizing on cast Fe3Al alloy. The Fe3Al alloy was anodized in 3 electrolytes with different water-ethylene glycol (EG) ratios (pure water, 25 vol.%-EG, and 50 vol.%-EG solutions) at a constant tartaric-sulfuric acids concentration, different voltages (10–20 V) and treatment times (2–60 min). After anodizing, all anodic oxide layers were annealed at 900 °C to form semiconductive iron-aluminum crystalline phases. Conventional techniques were used to systematically ascertain the morphological (SEM/EDS, XRD, eddy-current measurements) and semiconductive (UV–VIS reflectance spectroscopy) properties of these oxide layers. The results confirmed the formation of homogeneous and self-ordered anodic oxide layers at 10 and 15 V, regardless of the electrolyte composition. Namely, anodic films formed in electrolytes containing EG showed lower pore sizes, growth rates, and film thicknesses than those anodic films formed in the aqueous-based electrolyte. The annealing post-treatment results in different Fe-Al oxides (FexOy, FeAl2O4, etc.) with superior band gap values than those for non-annealed films.

Native Silicon Oxide Properties Determined by Doping.

The physico-chemical properties of native oxide layers, spontaneously forming on crystalline Si wafers in air, can be strictly correlated to the dopant type and doping level. In particular, our investigations focused on oxide layers formed upon air exposure in a clean room after Si wafer production, with dopant concentration levels from ≈1013 to ≈1019 cm-3. In order to determine these correlations, we studied the surface, the oxide bulk, and its interface with Si. The surface was investigated using the contact angle, thermal desorption, and atomic force microscopy measurements which provided information on surface energy, cleanliness, and morphology, respectively. Thickness was measured with ellipsometry and chemical composition with X-ray photoemission spectroscopy. Electrostatic charges within the oxide layer and at the Si interface were studied with Kelvin probe microscopy. Some properties such as thickness, showed an abrupt change, while others, including silanol concentration and Si intermediate-oxidation states, presented maxima at a critical doping concentration of ≈2.1 × 1015 cm-3. Additionally, two electrostatic contributions were found to originate from silanols present on the surface and the net charge distributed within the oxide layer. Lastly, surface roughness was also found to depend upon dopant concentration, showing a minimum at the same critical dopant concentration. These findings were reproduced for oxide layers regrown in a clean room after chemical etching of the native ones.

Ignition and combustion characteristics of boron-based nanofluid fuel

With its high gravimetric and volumetric heat value, boron-based nanofluid fuel is potentially well suited for future high-energy propulsion systems. In this experimental study, we investigate the ignition and combustion of boron-based nanofluid fuel, with a focus on the effects of oleic acid (OA) concentration (0 to 10 wt.%), boron particle concentration (2.5 to 20 wt.%), and boron particle size (300 nm to 13 µm). Thermogravimetry−differential scanning calorimetry and laser ignition tests reveal that adding boron nanoparticles to a fuel can improve its combustion intensity, but without much affecting the oxidation and ignition characteristics, primarily because of agglomeration and thicker oxide layer properties relative to boron microparticles. Pure kerosene droplets are found to undergo pre-ignition heating and classic combustion, whereas OA or boron addition promotes puffing and micro-explosions, accelerating the classic combustion process. The co-existence of OA and boron is found to lead to more frequent and stronger disintegration of the nanofluid fuel droplet. The ignition delay reaches 156 ms with only 2.5 wt.% OA inclusion, compared to just 73 ms for pure kerosene. Both the ignition delay and combustion rate increase, while the solid residual decreases owing to enhanced micro-explosions as the OA concentration increases. Unlike OA, boron addition promotes ignition, with 2.5 wt.% boron yielding an ignition delay reduction of 24 ms, but this effect weakens with increasing boron concentration. The combustion rate is found to be relatively insensitive to boron addition. Although the particle size affects the ignition and combustion performance of boron powder, its effect on the combustion of the nanofluid fuel droplet is, under the present test conditions, relatively weak. Finally, a phenomenological model is presented to capture the ignition and combustion of a boron-based nanofluid fuel droplet. The predicted ignition delay and combustion rate are found to be within 7.15% of their experimental values. This study contributes to an improved understanding of boron ignition and combustion in high-energy liquid fuel systems.

Effect of Graphene Addition During Micro-Arc Oxidation Process on Wear and Corrosion Properties of Composite Oxide Layers

Effect of Graphene Addition During Micro-Arc Oxidation Process on Wear and Corrosion Properties of Composite Oxide Layers

Effect of Concentration of SiO2 Nanoparticles in the Electrolyte on the Composition and Properties of Oxide Layers Formed by Plasma-Electrolytic Oxidation on Silumin AK7

Effect of Concentration of SiO2 Nanoparticles in the Electrolyte on the Composition and Properties of Oxide Layers Formed by Plasma-Electrolytic Oxidation on Silumin AK7

Characteristics of High-Power Impulse Magnetron Sputtering ITO/Ag/ITO Films for Application in Transparent Micro-LED Displays

In this study, a blue transparent micro-LED display with a chip size of 20 μm × 20 μm, a pixel density of 152 PPI, a pixel spacing of 150 μm, and a resolution of 64 × 32 has been fabricated. ITO/Ag/ITO transparent layers were deposited by high-power impulse magnetron sputtering. Sheet resistance was used to analyze the electrical properties of the indium tin oxide (ITO) layers, whereas scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to examine the surface morphology. These results demonstrate that the ITO/Ag/ITO structure with 20 nm thick Ag has a lower sheet resistance (3.36 Ω/sq) and sufficient visible light transmittance (80.45%). The visible light transmittance of the ITO/Ag/ITO layers increased to 86% after rapid thermal annealing. In addition, surface roughness was minimized, and sheet resistance was further reduced, resulting in ohmic contact on n-GaN that is suited for applications involving transparent micro-LED displays.

Realization of tuneable ultrabroadband interconnection for solitonic-plasmonic synapsis by exploiting epsilon near zero conducting oxides

This research introduces a novel highly efficient method to interconnect two metallic nanostrips that support the propagation of surface plasmon polariton (SPP) waves exploiting photorefractive soliton guide. The intricate design of the multilayer geometry enables light control diffraction at the metallic nanostrip’s end and reduces its angular dispersion. Moreover, the system’s on/off state can be switched by exploiting the epsilon near zero properties of the indium tin oxide (ITO) layer. The photorefractive crystal positioned between the two plasmonic waveguides enables the self-confinement of light, generating a waveguide that can be utilized by both the writing light and other wavelengths transmitted as signals. The resulting SPP waves can be efficiently recoupled in the second nanostrip, with an efficiency of around 40% across a broad range of wavelengths. This cutting-edge approach paves the way for significant advancements in the field of nanophotonics and provides a fundamental framework for the development of new, highly efficient optical interconnects in nanoscale systems. The findings of this study have implications for a wide range of applications, including nanoscale sensing, optical computing, and data communication.

Enhancement of the corrosion properties of selective laser melted Co-Cr-Mo alloy by selective oxidation annealing

This study investigated the surface modification effect of the selective oxidation annealing (SOA) on the corrosion properties of cobalt‑chromium‑molybdenum (Co-Cr-Mo) alloy fabricated by selective laser melting (SLM). For the SOA, each element's oxidation driving force was calculated, and the condition in which only Cr was selectively oxidized was thermodynamically analyzed. The oxidation potential was controlled by the partial pressure ratio of hydrogen gas and water vapor, and the alloy samples were annealed following the condition of the selective oxidation of Cr. The changes in the oxide layer and corrosion properties according to the SOA time were examined. On the as-built sample's surface, a very thin native oxide film was formed. After the SOA, a dense chromium oxide (Cr 2 O 3 ) layer was formed on the surface, and its thickness increased along with the SOA time. These changes in the oxide layer had an impact on corrosion properties. Even though all samples before and after the SOA were under the passivation state, the corrosion performances in terms of corrosion potential and corrosion current density were improved by the SOA. The electrochemical impedance spectroscopy (EIS) results further confirmed that the improved corrosion resistance mainly came from the increased oxide layer resistance ( R o ) because of the thickened oxide layer. • The surface of the selective laser melted Co-Cr-Mo alloy was modified by the selective oxidation annealing. • The Cr 2 O 3 oxide layer was formed on the alloy surface by the selective oxidation of Cr. • The thickness of the Cr 2 O 3 oxide layer increased with the increasing the selective oxidation annealing time. • The corrosion potential and corrosion current density improved by adopting the selective oxidation annealing.

Влияние добавки наночастиц ZrO2 в электролит на структуру и антикоррозионные свойства оксидных слоев, формируемых плазменно-электролитическим оксидированием на сплаве Mg97Y2Zn1

Magnesium alloys with a strengthening long-period stacking ordered structure (LPSO-phase) offer outstanding mechanical properties, but their low corrosion resistance necessitates additional surface protection. The work investigates the influence of adding ZrO2 nanoparticles at a concentration of 1–4 g/l to the electrolyte on the thickness, structure, composition, wettability, and anticorrosion properties of oxide layers formed during plasma electrolytic oxidation (PEO) of the Mg97Y2Zn1 alloy with the LPSO-phase. It was found that during PEO, under the influence of an electric field, ZrO2 nanoparticles penetrate into the forming oxide layer and reduce its porosity. The study revealed a decrease in the quantity and size of pores near the barrier layer in places where the alloy LPSO-phase comes out to the interface with the oxide layer. Low concentrations of ZrO2 nanoparticles (1–2 g/l) reduce the corrosion rate of the alloy up to two times compared to the base case. The minimum corrosion current density icorr≈14 nA/cm2 and the highest polarization resistance Rp≈2.6 MΩ·cm2 are found in the sample formed in an electrolyte with the addition of 1 g/l of ZrO2 nanoparticles. Calculation of the barrier zone parameters of oxide layers showed that an increase in the ZrO2 concentration in the electrolyte leads to an increase in the barrier layer thickness and in its specific conductivity, which negatively affects the corrosion resistance of the formed oxide layers – the barrier zone resistance of the layer obtained by adding 4 g/l of ZrO2, drops by ~20 % compared to the base case (up to ~1 MΩ·cm2).

Influence of Surface Preparation on Corrosion Resistance Properties of Oxide Layers Formed on Mag-nesium Alloy МА8 by Microarc Oxidation

The article presents the findings on the effect of the substrate pre-impregnation in the ceri-um (III) nitrate and glycerin aqueous solutions on the corrosion-protective properties of the coatings generated on the magnesium alloy MA8 surface by microarc oxidation. The coat-ings were formed in the A-K mode from a silicate-alkaline base electrolyte solution contain-ing compounds with fluoride ions. The corrosion resistance of the magnesium alloy ensured by oxide-ceramic coatings and without them was evaluated by the electrochemical corrosion parameters: corrosion potential, corrosion current density, and polarization resistance. The study has shown that the coatings formed on the surface of the magnesium alloy MA8 provide effective anticorrosive properties of the substrate of MA8 in the solutions containing chloride ions. It was established that the preliminary impregnation of a substrate made of magnesium alloy MA8 in aqueous solutions of cerium (III) nitrate and glycerin affects the mechanism of the resulting corrosion damage.