Effect Of Oxygen Partial Pressure Research Articles

Effects of oxygen partial pressure within the growth ambient on the properties and defect behavior of magnetron sputtered InCdO films

Abstracts Effects of the oxygen partial pressure within the Ar process plasma and the annealing treatment on the properties of magnetron sputtered In0.025Cd0.975O films were investigated in detail. It was observed that the electrical resistivity drastically increases with the oxygen addition, from 4.8 × 10−5 Ω∙cm at [O2] = 0% to 5.5 × 10−3 Ω∙cm at [O2] = 100%, and the carrier concentration and the electron mobility substantially decreased. It was also observed that the resistivity slightly decreased by the vacuum annealing but increased by the annealing in pure oxygen. Detailed characterization indicated that concentration of the oxygen vacancy (VO) donor is reduced and the oxygen interstitial (Oi) acceptors are formed within the samples grown in the O2-mixed ambient. It was proposed that the electrical properties of the InCdO films may be reasonably explained by the compensation model involving VO, Oi, In dopants, and/or their acceptor-like complexes.

Effect of Oxygen Partial Pressure on Solid Oxide Electrolysis Cells

High-temperature (700-900 degrees C) steam electrolysis based on solid oxide electrolysis cells (SOECs) is valuable as an efficient and clean path for large-scale hydrogen production with nearly zero carbon emissions, compared with the traditional paths of steam methane reforming or coal gasification. The operation parameters, in particular the feeding gas composition and pressure, significantly affect the performance of the electrolysis cell. In this study, a computational fluid dynamics model of an SOEC is built to predict the electrochemical performance of the cell with different sweep gases on the oxygen electrode. Sweep gases with different oxygen partial pressures between 1.01 x 10(3) and 1.0 x 10(5) Pa are fed to the oxygen electrode of the cell, and the influence of the oxygen partial pressure on the chemical equilibrium and kinetic reactions of the SOECs is analyzed. It is shown that the rate of increase of the reversible potential is inversely proportional to the oxygen partial pressure. Regarding the overpotentials caused by the ohmic, activation, and concentration polarization, the results vary with the reversible potential. The Ohmic overpotential is constant under different operating conditions. The activation and concentration overpotentials at the hydrogen electrode are also steady over the entire oxygen partial pressure range. The oxygen partial pressure has the largest effect on the activation and concentration overpotentials on the oxygen electrode side, both of which decrease sharply with increasing oxygen partial pressure. Owing to the combined effects of the reversible potential and polarization overpotentials, the total electrolysis voltage is nonlinear. At low current density, the electrolysis cell shows better performance at low oxygen partial pressure, whereas the performance improves with increasing oxygen partial pressure at high current density. Thus, at low current density, the best sweep gas should be an oxygen-deficient gas such as nitrogen, CO2, or steam. Steam is the most promising because it is easy to separate the steam from the by-product oxygen in the tail gas, provided that the oxygen electrode is humidity-tolerant. However, at high current density, it is best to use pure oxygen as the sweep gas to reduce the electric energy consumption in the steam electrolysis process. The effects of the oxygen partial pressure on the power density and coefficient of performance of the SOEC are also discussed. At low current density, the electrical power demand is constant, and the efficiency decreases with growing oxygen partial pressure, whereas at high current density, the electrical power demand drops, and the efficiency increases.

The Effect of Oxygen Partial Pressure and Annealing Process on the Characteristics of ZnGa2O4 MSM UV Photodetector

In this work, ZnGa2O4 solar-blind photodetectors (PD) based on a metal-semiconductor-metal (MSM) structure was fabricated by radio frequency (RF) magnetron sputtering method. The transmittance of the material shows larger than 80% cross the visible light region. As a wide bandgap and high transparency semiconducting material, ZGO is a potential candidate for UV-detection applications. The ZGO MSM PD with no oxygen flow during sputtering exhibits a responsivity of 4.46 × 10−2 A/W under illumination at wavelength of 260 nm, rejection ratio of 1.75 × 104. The performance can be enhanced with proper thermal annealing process. With an annealing process at temperature of 200°C, the responsivity and rejection ratio are 0.203 A/W and 1.12 × 105, respectively.

Effect of oxygen partial pressure on the growth of molybdenum trioxide thin films

Abstract Molybdenum Trioxide (MoO3) has high-stability, memory effect, response time and life time. Therefore it has started taking a very useful role in modern day advancements of electronics, electrochemical and optoelectronic devices. In current investigation, molybdenum trioxide thin film was deposited by thermal deposition method onto Indium Tin Oxide (ITO) Coated glass substrates. Effect of oxygen with precise regulation of pressure on the growth of films is aimed to study. MoO3 films are grown under vacuum of 2 × 10−5 mbar as well as under pressure of 2 × 10−4 mbar by introducing Oxygen. During the process, substrate temperature (TS) is maintained at 150 °C. The structural, morphological, vibrational, optical and electrochromic properties were systematically studied by using the characterization techniques such as XRD, SEM, EDS, FTIR, UV–VIS spectrophotometry and Cyclic-Voltammetry. The transformation of structural phase is clearly observed due to the presence of oxygen at the mentioned pressure. Optical data indicates direct allowed transition and optical band gap rises with presence of oxygen. The coloration efficiency of the films have been discussed.

Effect of Ambient Oxygen Partial Pressure on the Hydrogen Response of SnO2 Semiconductor Gas Sensors

In this study, the influence of the oxygen partial pressures (PO2) on the sensor response to H2 of SnO2 resistive-type gas sensors was evaluated under various humid atmospheres. SnO2 nanoparticles of 8–15 nm in diameter were synthesized using a hydrothermal technique followed by calcination at 600°C. Additionally, a large amount of pores with diameters greater than 10 nm was confirmed in the nanoparticles. The electrical resistance at 350°C was decreased with decreasing the PO2, and the electrical resistance in the presence of 10 ppm H2 was much smaller than that in the absence of H2 in both dry and humid atmospheres regardless of the PO2. Furthermore, the sensor response to 10 ppm H2 at 350°C increased with decreasing PO2 in both dry and humid atmospheres. Thus, decreasing the amount of oxygen adsorption enhanced the effect of rooted hydroxyl formation on the SnO2 surface through a combustion reaction between H2 and adsorbed oxygen and improved the sensor response to H2. These results are important for understanding the fundamental mechanisms of gas detection and for the material surface design of highly sensitive resistive-type semiconductor gas sensors.

Ambient-Pressure X-ray Photoelectron Spectroscopy Characterization of Radiation-Induced Chemistries of Organotin Clusters.

Advances in extreme ultraviolet (EUV) photolithography require the development of next-generation resists that allow high-volume nanomanufacturing with a single nanometer patterning resolution. Organotin-based photoresists have demonstrated nanopatterning with high resolution, high sensitivity, and low-line edge roughness. However, very little is known regarding the detailed reaction mechanisms that lead to radiation-induced solubility transitions. In this study, we investigate the interaction of soft X-ray radiation with organotin clusters to better understand radiation-induced chemistries associated with EUV lithography. Butyltin Keggin clusters (β-NaSn13) were used as a model organotin photoresist, and characterization was performed using ambient-pressure X-ray photoelectron spectroscopy. The changes in relative atomic concentrations and associated chemical states in β-NaSn13 resists were evaluated after exposure to radiation for a range of ambient conditions and photon energies. A significant reduction in the C 1s signal versus exposure time was observed, which corresponds to the radiation-induced homolytic cleavage of the butyltin bond in the β-NaSn13 clusters. To improve the resist sensitivity, we evaluated the effect of oxygen partial pressure during radiation exposures. We found that both photon energy and oxygen partial pressure had a strong influence on the butyl group desorption rate. These studies advance the understanding of radiation-induced processes in β-NaSn13 photoresists and provide mechanistic insights for EUV photolithography.

Effect of Annealing Oxygen Partial Pressure on Transmittance and Conductivity of AZO Thin Films

Effect of Annealing Oxygen Partial Pressure on Transmittance and Conductivity of AZO Thin Films

Effect of Oxygen Partial Pressure and Sintering Temperature on the Evaporation of Elements during Sintering in In-Sn-Zn-O Transparent Conducting Oxide Systems

Effect of Oxygen Partial Pressure and Sintering Temperature on the Evaporation of Elements during Sintering in In-Sn-Zn-O Transparent Conducting Oxide Systems

Optimization of Mineralogy and Microstructure of Solidified Basic Oxygen Furnace Slag Through SiO2 Addition or Atmosphere Control During Hot-Stage Slag Treatment

Valorization of basic oxygen furnace (BOF) slag is of significant importance for mitigation of the steel production’s environmental impact. The present work aims to investigate the influence of SiO2 addition and oxygen partial pressure on the mineralogical modification of a typical industrial BOF slag. The slag basicity (mass ratio of CaO/SiO2) was varied from 1.8 to 4.4 by mixing specific amounts of SiO2 with the master BOF slag. The original and modified slags were remelted and solidified under argon or air atmosphere followed by slow cooling. The experimental observations were then compared with the results of thermodynamic modeling to achieve a thorough understanding. With decreasing the basicity, free lime was eliminated, as it forms dicalcium silicate (Ca2SiO4). With increasing oxygen partial pressure, wustite was oxidized to hematite, which combined with free lime to form calcium aluminoferrite (C2AF). The effects of SiO2 addition and oxygen partial pressure were finally evaluated with respect to the energy consumption for the BOF slag valorization. The modified slag is suitable as a precursor for construction applications as binders.

On the reactive wetting of a medium-Mn advanced high-strength steel during continuous galvanizing

The effects of process atmosphere oxygen partial pressure (pO2) and Sn-addition on the reactive wetting of a prototype medium manganese third generation advanced high strength steel by a 0.20 wt% Al (dissolved) zinc bath was determined through galvanizing simulations. External MnO layers with thicknesses ranging from 19 nm to 45 nm were formed after annealing for 120 s at 690 °C under a variety of experimental process atmospheres. Despite the presence of surface oxides prior to immersion, an integral zinc coating and good coating adherence was obtained on all steel substrates, with the exception of the reference steel annealed under the lowest pO2−50 °C dew point process atmosphere, which exhibited poor reactive wetting. Excellent reactive wetting was demonstrated by the Sn-containing steels annealed under the −30 °C and +5 °C atmospheres. It was determined that the Al uptake as well as the population of the Fe-Al intermetallics at the coating/steel interface increased as a result of annealing under the higher pO2 atmospheres and adding Sn to the steel. The significant improvement in reactive wetting of the Sn-added steel was attributed to the decreased surface enrichment of Mn and the discrete distribution of the fine external oxide particles formed on the surface of these steel prior to dipping; which allowed for progression of reactive wetting through mechanisms such as the aluminothermic reduction of MnO, oxide bridging and oxide lift-off by the molten galvanizing bath.

Effect of Oxygen Partial Pressure on the Phase Stability of Copper⁻Iron Delafossites at Elevated Temperatures.

Oxide-based materials are promising candidates for use in high temperature thermoelectric generators. While their thermoelectric performance is inferior to commonly used thermoelectrics, oxides are environmentally friendly and cost-effective. In this study, Cu-based delafossites (CuFeO2), a material class with promising thermoelectric properties at high temperatures, were investigated. This work focuses on the phase stability of CuFeO2 with respect to the temperature and the oxygen partial pressure. For this reason, classical material characterization methods, such as scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, were combined in order to elucidate the phase composition of delafossites at 900 °C at various oxygen partial pressures. The experimentally obtained results are supported by the theoretical calculation of the Ellingham diagram of the copper–oxygen system. In addition, hot-stage X-ray diffraction and long-term annealing tests of CuFeO2 were performed in order to obtain a holistic review of the phase stability of delafossites at high temperatures and varying oxygen partial pressure. The results support the thermoelectric measurements in previous publications and provide a process window for the use of CuFeO2 in thermoelectric generators.

Effects of oxygen partial pressure on the microstructure, electrical and optical properties of the Sn-doped In2O3 thin films

The effects of oxygen partial pressure on the microstructure, electrical and photo-sensitive properties of the Sn-doped In2O3 (ITO) films deposited by different Ar–O2 flow rates (10:0.4, 10:1, 10:1.8 and 10:3) were investigated systematically by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Hall effect, UV-Vis and optical measurements. The XRD and SEM measurements show that the ITO film deposited at oxygen flow rate of 0.4 sccm prefers to (400) orientation and has a rough sawtooth-shaped surface. However, the ITO films deposited at oxygen flow rates of 1 sccm, 1.8 sccm and 3 sccm prefer to (222) orientation and exhibit a flat smooth surface. The conductivity, mobility and photosensitive property of ITO films are also sensitive to oxygen flow rate. The ITO film deposited at oxygen flow rate of 0.4 sccm has a high carrier concentration (up to [Formula: see text] cm[Formula: see text]) and mobility (16.7 cm2/vs), low resistivity [Formula: see text], and a long response time but good sensitivity to ultraviolet light. It can be concluded that the surface morphology plays a dominant role in sensitivity to ultraviolet light. The good sensitivity of ultraviolet light is gained from the ITO film with sawtooth-shaped surface.

Effect of Process Atmosphere Dew Point and Tin Addition on Oxide Morphology and Growth for a Medium-Mn Third Generation Advanced Steel During Intercritical Annealing

The combined effects of process atmosphere oxygen partial pressure, annealing time, and a 0.05 wt pct Sn addition on the selective oxidation of a model 0.1C-6Mn-2Si third generation advanced high-strength steel (3G-AHSS) composition were investigated. External and internal oxidation of both steels were observed after intercritical annealing at 963 K (690 °C) for holding times of 60 to 600 seconds under all process atmosphere dew points explored—i.e., 223 K, 243 K, and 278 K (− 50 °C, − 30 °C, and + 5 °C). The external MnO morphology was changed from compact and continuous film-like nodules to a fine and discrete globular morphology, with thinner external oxides, for the Sn-added steel. Cross-sectional TEM analysis revealed that the Sn addition also resulted in significant refinement of the internal oxide network. Kinetic studies showed that both the external and internal oxidation followed a parabolic rate law, where the Sn addition to the steel chemistry resulted in lower external and internal oxidation rates. 3D atom probe tomography of the external oxide/steel interface showed that Sn was segregated to the interface with enrichment levels ten times the bulk value, which was concluded to be responsible for the observed morphological changes. The resultant refined external oxide structure is expected to have significant benefits with respect to reactive wetting by the continuous galvanizing bath.

Novel Composite Electrolytes of Zr0.92Y0.08O2-α(8YSZ)-Low Melting Point Glass Powder for Intermediate Temperature Solid Oxide Fuel Cells.

In this study, Zr0.92Y0.08O2-α(8YSZ) powders were synthesized by the sol-gel method. The chemical physics changes and phase formation temperature of 8YSZ crystal were determined by thermogravimetry analysis and differential scanning calorimetry (TGA-DSC). 8YSZ-low melting point glass powder (8YSZ-glass) composite electrolytes with various weight ratios were prepared and calcined at different temperatures. The X-ray diffraction (XRD) patterns of the composite electrolytes were tested. The effects of synthesis temperature, weight ratio, test temperature, and oxygen partial pressure on the conductivities of 8YSZ-glass composite electrolytes, were also investigated at 400–800 °C. The result of the logσ ~ log(pO2) plot indicates that the 8YSZ-20% glass (700 °C) is almost a pure ionic conductor. The oxygen concentration discharge cell illustrates that the 8YSZ-20% glass (700 °C) composite electrolyte is a good oxygen ion conductor.

Effect of oxygen partial pressure on the semiconducting properties of thermally grown chromia on pure chromium

Oxidation of chromium at 800 °C for 30 min at oxygen activity from 5.10−14 atm to 5.10−13 atm have been conducted to grow an insulating chromia. Microstructural and semiconducting properties have been investigated using electron microscopy and photoelectrochemistry. The scales always exhibit a duplex microstructure with equiaxed and columnar grains, as well as a both n-type and insulating semiconduction type. Successive oxidation tests have demonstrated the higher protective nature of this chromia scale compared to the air grown one. Chromia semiconducting properties are finally described vs. oxygen activity in a large range of variation.

Effect of High Oxygen Partial Pressure on Carrier Transport Mechanism in a-InGaZnO TFTs

In this paper, the influence of oxygen partial pressure ( ${P}_{\textsf {O2}}$ ) during physical vapor deposition on the field-effect mobility of amorphous InGaZnO (IGZO) thin-film transistor (TFT) is investigated in a wide range of ${P}_{\textsf {O2}}$ . The field-effect mobility reduced from 12 to 0.1 cm $^{\textsf {2}}/\textsf {V}~\cdot $ s when the ${P}_{\textsf {O2}}$ is increased from 0.3 to 1.5 mTorr. Temperature-dependent TFT measurements suggest that carrier transport in the TFTs deposited at the ${P}_{\textsf {O2}}$ of 0.3 mTorr can be described according to the multiple trap and release/percolation model. However, the carrier transport in the TFTs deposited at the ${P}_{\textsf {O2}}$ of 1.5 mTorr conforms to Mott’s variable-range hopping model. The elastic recoil detection analysis indicates that hydrogen concentration in the IGZO film increased with ${P}_{\textsf {O2}}$ . The X-ray photoelectron spectroscopy results indicate that In vacancy ( ${V}_{\textsf {In}}$ ) defects formed in the IGZO film deposited at high ${P}_{\textsf {O2}}$ . Scattering induced by hydrogen and pinning of Fermi level below the conduction band edge by ${V}_{\textsf {In}}$ are plausible reasons for the low field-effect mobility in TFTs deposited at high ${P}_{\textsf {O2}}$ .

Effect of dew point on the reactive wetting of a C-2Mn-1.3Si (wt%) advanced high strength steel during continuous galvanizing

The effect of oxygen partial pressure on the reactive wetting of a Fe-0.1C-2Mn-1.3Si (wt%) advanced high strength steel during continuous galvanizing was determined. The steel was intercritically annealed at 1093 K (820 °C) for 120 s in a N2–5 vol% H2 process atmosphere, where the oxygen potential was controlled by varying the process atmosphere dew points at 223 K (−50 °C), 243 K (−30 °C) and 278 K (+5 °C). All samples were immersed in a 0.2 wt% dissolved Al continuous galvanizing bath at 733 K (460 °C) for 4 s. For the 243 K (−30 °C) and 278 K (+5 °C) dew point atmospheres, a well-developed Fe-Al intermetallic layer, indicative of good reactive wetting, was observed due to the presence of either thin or plate/nodule-like oxides on the steel surface after annealing. This external oxide morphology facilitated contact between the Zn-alloy bath and the substrate via a variety of mechanisms, including interfacial infiltration through cracks due to thermal coefficient of expansion mismatch between the external oxide and substrate and aluminothermic reduction, which resulted in Fe dissolution from the substrate and consequent formation of the observed Fe-Al intermetallics. On the other hand, the poor reactive wetting observed for the samples annealed under the 223 K (−50 °C) dew point atmosphere was due to the formation of a thick, compact oxide layer on the steel surface, which provided an effective barrier between the substrate and Zn bath, preventing contact between the two phases and the required Fe dissolution from the substrate surface.

Microstructure and optical properties of Ba0.6Sr0.4TiO3 thin films prepared by pulsed laser deposition

Growth aspects of barium strontium titanate, Ba0.6Sr0.4TiO3 (BST) thin films grown on Si (100) and quartz substrates by pulsed laser deposition technique were investigated. The main objective of the work was to study the effect of substrate temperature and oxygen partial pressure on the microstructure and optical properties of the BST films. X-ray diffraction results revealed that the thin films were amorphous when the substrate temperature was up to 673 K and the crystallinity was found to be improved at the substrate temperature of 873 K. There was an increase in the lattice parameter value from 3.97 to 4.01 Å with an increase in the oxygen partial pressure. Scanning electron microscopy revealed smooth and uniform surfaces, while atomic force microscopy revealed that the particle size increased with decreasing oxygen partial pressure. UV-visible spectroscopy showed that the band gap of the BST films deposited on quartz substrate decreased from 4.41 to 3.73 eV as deposition temperature increased from 303 K to 873 K.

Switch in photocatalytic reaction selectivity: The effect of oxygen partial pressure on carbon-carbon bond dissociation over hydroxylated TiO2(1 1 0) surfaces

Photocatalytic oxidation of ethanol over rutile TiO2(1 1 0) in the presence of O2 have been studied with scanning tunneling microscopy and on-line mass spectrometry to elucidate the reaction mechanisms. The O2 partial pressure has a direct impact on CC bond cleavage, resulting in a shift of selectivity in gas phase products from acetaldehyde (dehydrogenation) to methyl radicals (CC bond dissociation) with increasing pressure. This differs from the behavior of anatase TiO2(1 0 1) single crystal, where at all investigated pressures negligible CC bond dissociation occurs. The prevalence of the methyl radical species at high oxygen pressures is correlated with an increase in the surface population of an adsorbed species bound to Ti5c after the reaction, which are identified as formate moieties. Parallel XPS C1s, Ti2p and O1s further confirmed the assignment of surface population, by STM, to ethoxides at 300 K, in dark conditions (C1s at 286.7 and 285.4 eV attributed to CH2O and CH3 groups respectively). After photoreaction, a large fraction of the surface was covered by formates (XPS C1 at 289.7 eV). This also correlated with the STM assignment where species spaced by 6 Å along the [0 0 1] direction and with a height of ca. 1.1 Å attributed to formates. Moreover the profile for CH3 radical desorption in the gas phase as a function O2 partial pressures correlated with the increasing surface population of formates. Analysis of the rate of methyl radical formation reveals fast and slow regimes, with photoreaction cross-sections between 10−17 cm2 and 10−19 cm2. The parallel channel of acetaldehyde production has a non-varying cross-section of ca. 2 × 10−19 cm2. A schematic description of the two different reaction channels (dehydrogenation and CC bond dissociation) is given and discussed.

Effect of oxygen partial pressure on grain-boundary transport in alumina

The oxidation of the bond coat in a thermal barrier coating results in the formation of a protective alumina scale. Such scales experience large gradients in oxygen partial pressure (PO2) during formation, but it is unclear how PO2 affects grain-boundary (GB) transport in alumina. To study the effect of PO2 on GB kinetics in alumina, the rate of oxygen penetration was measured at 1400 °C over a wide range of PO2. This was accomplished using a novel reduction experiment using nickel aluminate spinel particles. The results indicated that the dependence of the boundary transport on PO2 is mainly due to the driving force, namely the gradient in PO2 across the alumina. Point-defect models were then invoked to interpret the measurements, and it was found that transport in an alumina scale is controlled by extrinsic defects.