Effect Of Oxygen Partial Pressure Research Articles

A core‐shell structured diffusion‐bubbling membrane for efficient oxygen separation: Formation and transport properties

AbstractThe newly developed core‐shell structured molten oxide membranes with fast combined diffusion‐bubbling oxygen mass transfer and theoretically infinite selectivity are of technological interest because of their high separation efficiency. In this article, a core‐shell structured molten V2O5–Cu2O‐ based diffusion‐bubbling membrane was prepared by one‐step thermal treatment of initial CuO–25 wt.% Cu5V2O10 ceramic composite in a chemical field (under an oxygen partial pressure difference across the composite) above copper vanadate peritectic transformation temperature (816°C). Oxygen fluxes through the membrane were measured at 830°C, using either gas mixtures (O2 + N2) with different oxygen concentrations or air as feed gas at the shell of the membrane and helium (He) as sweep gas. Oxygen flux through the membrane with a shell thickness of 0.15–0.61 mm was 3.8·10–8–1.4·10–7 mol/cm2/s under an oxygen partial pressure difference of 0.1 –0.75 atm, respectively. The effect of oxygen partial pressure on the thickness of the membrane shell is found. The relationship between membrane shell thickness, oxygen partial pressure difference across the membrane, and oxygen permeation flux through the membrane is established. Oxygen permeation flux through the dual‐phase MIEC membrane shell is described in terms of the diffusion model. Oxygen permeation flux through the membrane core is described both within the framework of the stationary model and nonstationary model for uniform (the membrane thickness is much larger than the characteristic distance of bubble dynamic relaxation) and accelerated (the membrane thickness is comparable to the characteristic distance of bubble dynamic relaxation) bubble motion in a viscous oxide melt, respectively.

Effects of Oxygen Partial Pressure and Substrate Temperature on the Structure and Morphology of Sc and Y Co-Doped ZrO2 Solid Electrolyte Thin Films Prepared via Pulsed Laser Deposition.

Scandium (Sc) and yttrium (Y) co-doped ZrO2 (ScYSZ) thin films were prepared on a SiO2-Si substrate via pulsed laser deposition (PLD) method. In order to obtain good quality thin films with the desired microstructure, various oxygen partial pressures ( from 0.01 Pa to 10 Pa and substrate temperatures (Ts) from 25 °C to 800 °C were investigated. X-ray diffraction (XRD) patterns results showed that amorphous ScYSZ thin films were formed at room substrate temperature while cubic polycrystalline thin films were obtained at higher substrate temperatures (Ts = 200 °C, 400 °C, 600 °C, 800 °C). Raman spectra revealed a distinct Raman shift at around 600 cm−1 supporting a cubic phase. However, a transition from cubic to tetragonal phase can be observed with increasing oxygen partial pressure. Photoemission spectroscopy (PES) spectra suggested supporting analysis that more oxygen vacancies in the lattice can be observed for samples deposited at lower oxygen partial pressures resulting in a cubic structure with higher dopant cation binding energies as compared to the tetragonal structure observed at higher oxygen partial pressure. On the other hand, dense morphologies can be obtained at lower (0.01 Pa and 0.1 Pa) while more porous morphologies can be obtained at higher (1.0 Pa and 10 Pa).

The Effect of Oxygen Partial Pressure and Humidification in Proton Exchange Membrane Fuel Cells at Intermediate Temperature

The Effect of Oxygen Partial Pressure and Humidification in Proton Exchange Membrane Fuel Cells at Intermediate Temperature

Investigation of the effect of oxygen partial pressure on the phase composition of copper oxide nanoparticles by vacuum arc synthesis

Copper oxide nanoparticles were obtained in the plasma of a low-pressure arc discharge. The effect of the partial pressure of oxygen (10-40%) on the physical properties of the deposited nanoparticles has been studied. X-ray diffraction analysis shows that the cubic structure of Cu2O changes to monoclinic CuO with increasing O2 pressure. The results of Raman spectroscopy further confirmed the phase variations of copper-based oxide nanoparticles. X-ray photoelectron spectroscopy confirmed the change in the binding energy in the oxidation state of nanoparticles. The optical band gap of the deposited Cu2O is 2.12 eV, while that of CuO is 1.79-1.82 eV. Keywords: vacuum arc, oxides, nanoparticles, plasma-chemical reactions.

Effect of growth parameters on defect structure and optical properties of ultrathin SnO2 films

Tin oxide films with thicknesses in the range from 5 to 110 nm have been deposited by reactive dc magnetron sputtering of Sn in Ar + O plasma at a low working pressure of 1.0× 10 −3 Torr on glass substrates at different temperatures (150–400 °C). The effect of deposition time, substrate temperature, and oxygen partial pressure on surface morphology , crystallographic structure, optical properties, and photoluminescence characteristics of SnO 2 films has been studied and correlated with their defect structure . The structural transformation from nanocrystalline to polycrystalline of thicker films >40 nm and films were grown at higher temperature is explained based on adatom mobility and uniform substrate coverage. Based on photoluminescence characteristics and transmittance spectra, the 20 nm thick film exhibits the least defect structure and best electronic and optical behaviors. • Ultrathin SnO 2 films (5–20 nm) are successfully grown by DC reactive sputtering. • Effect of scaling down film thickness (down to 5 nm) on physical properties. • Correlation between defect structure and optical properties. • Thinner films are much smoother than the thicker films. • Low structural defect concentration found in 10–40 nm films.

Effect of annealing and oxygen partial pressure on the RF sputtered WO3 thin films for electrochromic applications

the electrochromic thin layer of Tungsten trioxide (WO3) was RF sputtered on FTO (fluorine-doped tin oxide) slide. In a reactive Ar + O2 gas environment with varying oxygen partial pressures, the deposition continued. The samples were air annealed at 400 °C for 2 h after being deposited at room temperature. SEM, XRD, UV–Visible spectrometer, and electrochemical analyzer characterization methods were employed to analyze the surface, structural morphology, optical, and electrochromic behaviour of the deposited material after annealing. The Optical Bandgap and Transmittance were found to be of a higher value for air annealed samples than RT deposited samples because RT deposited samples are amorphous whereas air annealed samples exhibit crystalline nature with Oxidation, reduction peak currents variation with respect to the temperature.

Leaching behavior of zinc and lead from electric arc furnace dust – Poly(vinyl) chloride residues after oxidative thermal treatment

Oxidative thermal treatment of electric arc furnace dust (EAFD) mixed with poly(vinyl) chloride (PVC) was carried out to study the impact of oxidizing environment on the extraction of valuable metals. The effect of oxygen partial pressure, temperature and holding time of the thermal treatment, as well as the pH of the leaching solution were considered as operational variables in this study. HCl evolved during PVC decomposition was found to react with the metal oxides present in EAFD producing metal chlorides. It was found that thermal treatment above 350 °C caused significant vaporization of lead and zinc chlorides. After thermal treatment, the residue was leached in water, the cheapest available leaching reagent. Zinc and lead were extracted with recoveries up to ∼100%, while iron recovery was as low as 12.5% being suppressed by oxidation of ferrous iron. Operating under oxidative conditions supresses the post dissolution of iron in water by oxidizing Fe3O4 to Fe2O3 and by oxidizing any formed FeCl2 back to Fe2O3. The solution pH was also found to significantly affect the extraction of both lead and iron, especially at pH values above 4.0 where a sharp drop in metals recovery was observed. The obtained results present base for development of sustainable solution for treatment of PVC and EAFD wastes.

Effect of Oxygen Partial Pressure on the Stoichiometric Composition of Titanium Oxide Films during Magnetron Sputtering

Effect of Oxygen Partial Pressure on the Stoichiometric Composition of Titanium Oxide Films during Magnetron Sputtering

Unexpected atmosphere effect on the iron oxide growth by the Laser Floating Zone method

The control of the oxidation state represents an important challenge for materials engineering. It is fairly known that iron oxide can be present in several oxidation states each one with unique physical and chemical properties. In the present work the effects of the different oxygen partial pressure on the growth of Fe3O4 fibers, using hematite (Fe2O3) as a precursor material was studied. The fibers were grown by the Laser Floating Zone (LFZ) method at a constant pulling rate (100 mm/h) under different atmospheres (air, vacuum, argon and nitrogen). The structure and morphology of the as-grown fibers were studied by X-ray diffraction, SEM/EDS/EBSD and optical microscopy. The fibers show a core/shell structure, where Fe3O4 is the core and Fe2O3 the shell, putting in evidence that the partial pressure of oxygen is a crucial parameter to control the thickness and grains morphology of the shell. Low oxygen partial pressure increases the width of the Fe2O3 insulating phase shell. The electrical conductivity, of the samples grown under an atmosphere with low oxygen partial pressure, is improved due to the morphology of the grains in the shell. However, no significant changes in the magnetization measurements were detected. From the results, we can conclude that applying an atmosphere during the LFZ growth allows tunning the transport properties envisaging electrical applications of the as-grown material.

Physical and chemical regularities of zinc sulfide concentrate pressure leaching in the presence of lignosulfonate

The study covers physical and chemical regularities of zinc sulfide concentrate oxygen pressure leaching in sulfuric acid. The effect of lignosulfonate concentration (CLSN = 0.2÷0.8 g/dm3), leaching time (τ = 20÷120 min), temperature (T = 393÷423 K), and oxygen partial pressure (РО2= 0.3÷0.7 MPa) on the degree of zinc and iron extraction into the solution and on the cake grain-size distribution was established. It was shown that lignosulfonate additive intensifies zinc and iron extraction into the solution. Maximum extraction of zinc and iron was 89 and 37 %, respectively, for 120 min of leaching at CLSN = 0.6÷0.8 g/dm3. The differential rate law with respect to lignosulfonate was 0.3 for sphalerite, and 0.9 for iron sulfides. A controversial influence of rising temperature on the process under investigation was found. Temperature elevation from 413 to 423 K leads to a decrease in zinc extraction by 3–4 % due to the formation of sulfur-sulfide aggregates over 150 μm in size. The calculated values of apparent activation energy (Еа) of sphalerite and iron sulfide leaching in the presence of lignosulfonate were 30 and 45 kJ/mole, respectively. It was found out that an increase in oxygen partial pressure from 0.3 to 0.5 MPa has a positive influence on leaching and increases extraction of zinc and iron by 22 and 27 %, respectively. However, an increase in oxygen partial pressure up to 0.7 MPa in the presence of lignosulfonate after 40 min of leaching led to a decrease in leaching rate, possibly as a result of lignosulfonate destruction. It was found that differential rate laws with respect to oxygen are 1.2 for sphalerite and 2.5 for iron sulfides.

Effect of Oxygen Partial Pressure on Reactive-Sputtered Ni-YSZ Anode Properties for Low-Temperature Solid Oxide Fuel Cell

Solid oxide fuel cell (SOFC) is a promising next-generation energy conversion device because of its high efficiency, cleanliness, and fuel flexibility. Recently, SOFC operating at low- to intermediate-temperature (LT to IT) range (< 600 ℃) has been studied to overcome the limitations of conventional SOFC, e.g., thermal stability, cost, and limited application. In lowered temperature range, however, charge transfer and transport rates slow down; therefore, SOFCs design with thin film stacks, namely thin film SOFC (TF-SOFC) fabricated on porous anode support have been usually adopted for sufficient power density even at this temperature regime.TF-SOFC usually uses Ni-YSZ (nickel-yttria-stabilized zirconia) cermet for anode functional layer (AFL) to accommodate the deposition of dense electrolyte layers on anode support with relatively large pores because of its reasonable cost, catalytic activity, and electrical conductivity. While various thin film techniques have been reported for AFL fabrication, e.g., pulsed layer deposition (PLD), RF sputtering, etc. Among such techniques, reactive sputtering method, which uses metal target in controlled gas environment (e.g., oxygen environment for oxide deposition), is a versatile method to deposit various types of thin films with fast speed (up to > 1um/hr), which is beneficial in manufacturabilily regarding the usual thickness range of AFL (a few microns). Furthermore, the reactive co-sputtering method can control anode properties such as composition ratio, deposition speed, and morphology in wide ranges.In this study, we fabricate reactive sputtered Ni-YSZ cermet anodes, as prototypes for AFLs of TF-SOFCs, by using a single metal target with various oxygen partial pressure conditions, and characterize their physical and chemical properties. Oxygen partial pressure significantly affects deposition speed, surface morphology, composition, electrochemical performance and its thermal durability at 450 ℃. The Ni-YSZ anode sputtered at the environment of O2/Ar partial pressure ratio of 0.1 sample shows the lowest activation resistance when applied to LT-SOFC’s anode. It is also shown that excessive O2/Ar partial pressure ratio (> 0.2) significantly reduces the deposition speed by approximately one order of magnitude compare to the lower ratio case.

Concentration effect on oxygen quenching behavior of EuxY0.08‐xZr0.92O1.96 and DyxY0.08‐xZr0.92O1.96 phosphors

AbstractThe effect of oxygen partial pressure on the phosphorescence of EuxY0.08‐xZr0.92O1.96 and DyxY0.08‐xZr0.92O1.96 (x = 0.001, 0.005, 0.01, 0.02, 0.05) phosphors was investigated and compared to explore the Ln3+ (Ln3+ = Eu3+, Dy3+) concentration effect on oxygen quenching using a lifetime‐based measurement system equipped with a heatable and pressure controllable chamber. The phosphorescence lifetimes of these two series of phosphors were found to be sensitive to the oxygen partial pressure in high‐temperature environments. Surprisingly, the oxygen sensitivity of DyxY0.08‐xZr0.92O1.96 phosphors markedly increases as the Dy3+ concentration increases, while that of EuxY0.08‐xZr0.92O1.96 phosphors remains nearly constant. Further analysis shows that the oxygen quenching phenomenon is attributable to an oxygen vacancy‐induced non‐radiative decay reduction. However, the mechanisms of non‐radiative decay affected by oxygen vacancies differ, with a charge transfer state (CTS) transition mechanism in EuxY0.08‐xZr0.92O1.96 and a cross‐relaxation mechanism in DyxY0.08‐xZr0.92O1.96 phosphors. The CTS measured from the excitation spectrum is found to be independent of the Eu3+ concentration. In contrast, cross‐relaxation is closely related to the Dy3+ concentration, as demonstrated by the concentration‐quenching behaviours of the phosphorescence intensities and lifetimes, and the non‐exponential decay curves. The present research was expected to shed light on the development and optimization of oxygen/pressure sensors for high‐temperature service.

Effect of Oxygen Partial Pressure on Crystal Structure, Oxygen Vacancy, and Surface Morphology of Epitaxial SrTiO3 Thin Films Grown by Ion Beam Sputter Deposition

Epitaxial SrTiO3 (STO) thin films were grown on (001)-oriented LaAlO3 (LAO) substrates at 800 °C by an ion beam sputter deposition (IBSD). Oxygen partial pressure (PO2) was varied at 1.5 × 10−5, 1.5 × 10−4, and 1.5 × 10−3 Torr during the growth. The effects of PO2 on crystal structure, oxygen vacancy, and surface morphology of the STO films were investigated and are discussed to understand their correlation. It was found that PO2 played a significant role in influencing the crystal structure, oxygen vacancy, and surface morphology of the STO films. All STO films grew on the LAO substrates under a compressive strain along an in-plane direction (a- and b-axes) and a tensile strain along the growth direction (c-axis). The crystalline quality of STO films was slightly improved at higher PO2. Oxygen vacancy was favorably created in the STO lattice grown at low PO2 due to a lack of oxygen during growth and became suppressed at high PO2. The existence of oxygen vacancy could result in a lattice expansion in both out-of-plane and in-plane directions due to the presence of Ti3+ instead of Ti4+ ions. The surface roughness of the STO films gradually decreased and was nearly close to that of the bare LAO substrate at high PO2, indicating a two-dimensional (2D) growth mode. The results presented in this work provide a correlation among crystal structure, oxygen vacancy, and surface morphology of the epitaxial STO films grown by IBSD, which form a useful guideline for further study.

Effect of Sputtering Oxygen Partial Pressure on the Praseodymium-Doped InZnO Thin Film Transistor Using Microwave Photoconductivity Decay Method.

The praseodymium-doped indium-zinc-oxide (PrIZO) thin film transistor (TFT) shows broad application prospects in the new generation of display technologies due to its high performance and high stability. However, traditional device performance evaluation methods need to be carried out after the end of the entire preparation process, which leads to the high-performance device preparation process that takes a lot of time and costs. Therefore, there is a lack of effective methods to optimize the device preparation process. In this paper, the effect of sputtering oxygen partial pressure on the properties of PrIZO thin film was studied, and the quality of PrIZO thin film was quickly evaluated by the microwave photoconductivity decay (µ-PCD) method. The μ-PCD results show that as the oxygen partial pressure increases, the peak first increases and then decreases, while the D value shows the opposite trend. The quality of PrIZO thin film prepared under 10% oxygen partial pressure is optimal due to its low localized defect states. The electric performance of PrIZO TFTs prepared under different oxygen partial pressures is consistent with the μ-PCD results. The optimal PrIZO TFT prepared under 10% oxygen partial pressure exhibits good electric performance with a threshold voltage (Vth) of 1.9 V, a mobility (µsat) of 24.4 cm2·V−1·s−1, an Ion/Ioff ratio of 2.03 × 107, and a subthreshold swing (SS) of 0.14 V·dec−1.

Effects of temperature on the locomotor performance and contraction properties of skeletal muscle from two Phrynocephalus lizards at high and low altitude.

Locomotor performance and skeletal muscle contraction are critical for animals andare susceptible tochanges in the externalthermal environment, especially for ectotherms. Phrynocephalus erythrurus,which isendemic tothe Qinghai-Tibetan plateau, is known for living at the highest elevation among all reptiles in the world (4500-5300m). In this study, which comparesP. erythrurus withthe lowland Phrynocephalus przewalskii, we evaluated the locomotor performance at different body temperatures, the effects of temperature and oxygen partial pressure (PO2) on the contractile properties of iliofibularis (IF) muscle in vitro, ATPase activity of IF muscle at different temperatures, and the fiber types of IF muscle. Lowland P. przewalskii runs significantly faster than highland P. erythrurus at all test body temperatures. Almost all contractile properties of the IF muscle of P. przewalskii were better than that of P. erythrurus under all test temperatures and PO2. However, P. erythrurus could achieve both optimal isometric (e.g., dPo/dt) and optimal isotonic (e.g., Vmax) contraction at a lower temperature compared with P. przewalskii. Multi-factor analysis further revealed that temperature has a significant effect on the contractile properties of IF muscle for both species. Although the proportion of fibers types and ATPase activities of IF muscle have no significant interspecies difference, the changing pattern of ATPase activities with temperature is consistent with certain contractile properties and locomotor performance. The interspecies differences in locomotor ability and contractile properties of skeletal muscle in high- and low-altitude lizards may be the results of long-term adaptation tothe local environment.

The effects of soybean storage under controlled atmosphere at different temperatures on lipid oxidation and volatile compounds profile

This study aimed to evaluate the effects of low oxygen partial pressure (pO2) and high carbon dioxide partial pressure (pCO2) combined with different temperatures on the oil acidity and peroxide values of two soybean cultivars (NA 5909 RG and FEPAGRO 37 RR). The volatile compounds correlated to lipid oxidation were also evaluated. Soybeans were stored for seven months under ambient and controlled atmosphere (CA) conditions at three temperatures (20, 25, and 30 °C). Storage under ambient conditions increased acidity and peroxide value regardless of the temperature. CA storage with low pO2 reduced oil acidity and its combination with high pCO2 had no positive effects on oil acidity and peroxide values. Grains of FEPAGRO 37 RR stored under ambient air showed higher 1-octne-3-ol amount compared to CA. The higher storage temperature increased (E)-2-heptenal and decanal amount in grains of cultivar NA 5909 RG. In addition, the ambiente air storage provide higher γ-Butyrolactone in relation to CA storage. Moreover, in both cultivars the CA storage technique provides lower (E)-2-hexenal content. This compound, together with hexanal are potential lipid deterioration markers of soybeans. CA storage is a promising tool for soybean grains preservation and the effect is mainly due to the oxygen reduction, with no additional effect of CO2 increasing.

Effect of oxygen partial pressure on microstructure, optical and electrical property of C-Al co-doped ZnO films

C-Al co-doped ZnO films with superior optical and electrical property have been deposited at oxygen partial pressure range 1–7 Pa by pulse laser deposition. The influences of oxygen pressure on crystalline, optical and electrical property have been investigated. The C-Al co-doped ZnO films exhibit a superior crystallinity and greater grain size in the range of 1 Pa–3 Pa compared to AZO films. Furthermore, carbon doping at various oxygen partial pressure significantly improves the optical and electrical property. C-Al co-doped ZnO film reaches the lowest resistivity of 3.1×10-4 Ω cm at 1 Pa. The average transmittance is higher than 85% and attains the optimal value of 89.9 %.

Effect of oxygen partial pressure on the stability of Ce0.8Zr0.2O2-δ solid solution using genetic algorithm and lattice statics

Atomic distribution is a key parameter that determines the stability of solid solution materials. We studied the effect of oxygen partial pressure on atomic distribution in cubic Ce0.8Zr0.2O2-δ solid solutions. The oxygen partial pressure was varied by changing the number of the oxygen vacancies, and the cubic solid solutions were constructed from the 2×2×2 fluorite CeO2 supercell. We employed genetic algorithm and lattice statics to effectively find the energetically-favorable structures among a huge number of configurations.

Effect of processing parameters on the defects state in Ni0.65Zn0.35Al0.8Fe1.2O4 thin films

Ferromagnetic resonance (FMR) technique is used to investigate the effect of oxygen partial pressure (PO2) and substrate temperature (TS) on the defect properties of Ni0.65Zn0.35Al0.8Fe1.2O4 (NZAFO) thin films. NZAFO thin films are deposited on MgAl2O4 (MAO) (100) substrates using pulsed laser deposition technique under various PO2 and TS. The FMR study reveals that the FMR parameters such as linewidth, line intensity and g-factor of the NZAFO thin films are sensitive to the variations in PO2 and TS. The observed changes in the FMR parameters are attributed to the variation of density and uniformity of defects in NZAFO thin films. Thus the significance of the present work suggests that the FMR may serve as an effective tool to monitor the growth condition of complex oxide films.

Effects of Oxygen Partial Pressure on the Properties of SnOx Thin Films Doped with Indium

This study examined the effects of the oxygen partial pressure on the properties of heavily indium-doped tin-oxide (In-SnOx) thin films grown at room temperature by reactive direct-current pulse sputtering from a mixed metallic target containing Sn (70 atomic %)-In (30 atomic %). X-ray photoelectron spectroscopy (XPS), dynamic secondary-ion mass spectrometry, X-ray diffraction (XRD), and Hall Effect measurements showed that the In-SnOx samples prepared with oxygen pressures of 10–20% had metallic properties. This was attributed to the notable Sn0 area ranges of 5.6–17.3%, low resistivity ranges of 5.5×10−3–2×10−4 Ωcm, and the high carrier concentration ranges of 3.5×1021–5.1×1022/cm3. On the other hand, the Sn4+ area and the resistivity increased significantly to 73.3% and 9.4 Ωcm. In comparison, the Sn2+ area and the electron concentration decreased dramatically to 23.6% and 6.5×1016/cm3, respectively, with increasing oxygen partial pressure up to 30%. The samples prepared with oxygen pressures higher than 20% exhibited nonmetallic properties with the dominant n-type SnO2 phase. This steep increase in the Sn4+ area was attributed to an increase in the oxygen contents in the samples, resulting in a decrease in the number of oxygen vacancy donors in the samples prepared with oxygen pressures higher than 20%. The decrease in the Sn2+ area was related to a decrease in the indium (In) contents in the samples, which also decreased the number of metal acceptors in the samples. XRD also showed that the metallic indium stannide (In0.2Sn0.8) and In–Sn–O(ITO) peaks coexisted for samples prepared with an oxygen pressure of 0–10%. In contrast, the samples prepared with oxygen pressures higher than 20% had an amorphous structure with SnO2 and SnO phases, supporting the XPS and Hall Effect measurement results.