Effect Of Oxygen Flow Research Articles

Electronic vs phononic thermal transport in Cr-doped V2O3 thin films across the Mott transition

Understanding the thermal conductivity of chromium-doped V2O3 is crucial for optimizing the design of selectors for memory and neuromorphic devices. We utilized the time-domain thermoreflectance technique to measure the thermal conductivity of chromium-doped V2O3 across varying concentrations, spanning the doping-induced metal–insulator transition. In addition, different oxygen stoichiometries and film thicknesses were investigated in their crystalline and amorphous phases. Chromium doping concentration (0%–30%) and the degree of crystallinity emerged as the predominant factors influencing the thermal properties, while the effect of oxygen flow (600–1400 ppm) during deposition proved to be negligible. Our observations indicate that even in the metallic phase of V2O3, the lattice contribution is the dominant factor in thermal transport with no observable impact from the electrons on heat transport. Finally, the thermal conductivity of both amorphous and crystalline V2O3 was measured at cryogenic temperatures (80–450 K). Our thermal conductivity measurements as a function of temperature reveal that both phases exhibit behavior similar to amorphous materials, indicating pronounced phonon scattering effects in the crystalline phase of V2O3.

Effects of Oxygen Flow during Fabrication by Magnetron Sputtering on Structure and Performance of Zr-Doped HfO2 Thin Films.

Oxygen defects in Hafnium Oxide (HfO2)-based ferroelectric thin films not only are related to the cause of ferroelectricity but also affect the ferroelectric properties of the thin films. This paper, therefore, focuses on the fabrication of Zr:HfO2 thin films by RF (Radio Frequency) magnetron sputtering with Zr-doped HfO2 as the target and examines how oxygen flow impacts the oxygen vacancies and electrical properties thereof. Additionally, TiN thin-film electrodes were prepared by direct current (DC) magnetron reactive sputtering using nitrogen as the reaction gas, the influences of the substrate temperature on the film deposition rate and crystal phase structure were investigated, and the resultant thin-film electrodes with the lowest resistivity were obtained. Furthermore, the ferroelectric hysteresis loop and leakage current density of metal-insulator-metal (MIM) ferroelectric capacitors formed by annealing the 30 nm thick deposited Zr:HfO2 sandwiched between the top and bottom TiN electrodes were measured. The results demonstrate that varying oxygen flow has a considerable effect on oxygen vacancies and the Zr doping concentration of deposited Zr:HfO2 ferroelectric thin films. When the oxygen flow is set to 40 sccm (standard cubic centimeters per minute) and an external electric field strength of 2 mV/cm is applied, the remnant polarization reaches 18 μC/cm2, with a decrease in the leakage current density of 105-6 orders of magnitude.

Effect of oxygen flow on aerosol delivery from a vibrating mesh nebulizer with a holding chamber

BackgroundA holding chamber (HC) was created to work with a vibrating mesh nebulizer (VMN) to boost the total inhalable dose for patients. In addition to the optional supply of supplemental oxygen, it facilitates intermittent and continuous nebulization. Our goal was to see how well a VMN coupled to a HC with a mouthpiece or valved facemask performed at varied oxygen flows starting at 0–6 L/min. In this study, we used a breathing simulator to simulate adults' spontaneous breathing patterns with a tidal volume of 500 mL and a 1:1 inhalation–exhalation ratio. For the combination of nebulizer and HC adapter with a valved facemask or mouthpiece, five determinations were made. Salbutamol was recovered and evaluated using high-performance liquid chromatography from the inhalation filter connected to the breathing simulator, the nebulizer reservoir chamber, and the HC.ResultsThe amount of salbutamol in the nebulizer reservoir chamber and within the HC did not differ significantly when using a mouthpiece or a valved facemask. However, the supplied dose to the inhalation filter was increased until oxygen flow reached 2 and 3 L/min using the mouthpiece and valved facemask as interfaces, respectively. The supplied salbutamol was much higher at this flow than at the other oxygen flows. This was followed by a progressive reduction in the supplied salbutamol until the lowest given dose was reached at 6 L/min oxygen flow, p < 0.005.ConclusionsThe supplied doses of salbutamol to the inhalation filter were variable with the VMN connected to the HC and mouthpiece or valved facemask, with significant improvements until an oxygen flow of 2 L/min with a mouthpiece and 3 L/min with a valved facemask, followed by gradual decreases to lower values at an oxygen flow of 6 L/min. An in vivo investigation is required to further validate the findings.

Effect of oxygen flow on the optical properties of hafnium oxide thin films by dual-ion beam sputtering deposition

Effect of oxygen flow on the optical properties of hafnium oxide thin films by dual-ion beam sputtering deposition

Numerical Analysis of Oxygen-Related Defects in Amorphous In-W-O Nanosheet Thin-Film Transistor.

The integration of 4 nm thick amorphous indium tungsten oxide (a-IWO) and a hafnium oxide (HfO2) high-κ gate dielectric has been demonstrated previously as one of promising amorphous oxide semiconductor (AOS) thin-film transistors (TFTs). In this study, the more positive threshold voltage shift (∆VTH) and reduced ION were observed when increasing the oxygen ratio during a-IWO deposition. Through simple material measurements and Technology Computer Aided Design (TCAD) analysis, the distinct correlation between different chemical species and the corresponding bulk and interface density of states (DOS) parameters were systematically deduced, validating the proposed physical mechanisms with a quantum model for a-IWO nanosheet TFT. The effects of oxygen flow on oxygen interstitial (Oi) defects were numerically proved for modulating bulk dopant concentration Nd and interface density of Gaussian acceptor trap NGA at the front channel, significantly dominating the transfer characteristics of a-IWO TFT. Furthermore, based on the studies of density functional theory (DFT) for the correlation between formation energy Ef of Oi defect and Fermi level (EF) position, we propose a numerical methodology for monitoring the possible concentration distribution of Oi as a function of a bias condition for AOS TFTs.

Cuprous Oxide Films Deposition by Mid-Frequency Magnetron Sputtering and Their Photocatalytic Activity under Visible Light

Cuprous oxide (Cu2O) has attracted much attention as a photocatalytic material. In this paper, the mid-frequency reactive magnetron sputtering method was used to prepare Cu2O films on glass slides, and the effects of oxygen flow and deposition time on the structures, morphologies and photocatalytic properties of the films were studied. The results show that the films prepared by this method have smooth surfaces and good absorptivity in the visible region. As the oxygen flow increases, the films transit from the mixed-phase of Cu and Cu2O to the single-phase of Cu2O. When the oxygen flow continues to increase, the films change to a mixed-phase of Cu4O3 and Cu2O. The photocatalytic decolorization of methyl orange under visible light irradiation conditions was used to assess the photocatalytic properties of the prepared films. When the oxygen flow is 6[Formula: see text]sccm and the deposition time is 15[Formula: see text]min, the film exhibits the best photocatalytic activity. Finally, the Mulliken electronegativity theory was used to explain the photocatalytic mechanism of Cu2O. This study confirmed the feasibility of preparing Cu2O photocatalytic films by magnetron sputtering, and provided the experimental basis for the subsequent study of Cu2O photocatalytic films.

Oxygen-related Reliability of Amorphous InGaZnO Thin Film Transistors

Effects of oxygen flow on positive bias temperature instability and hot carrier injection are investigated in Amorphous InGaZnO (IGZO) thin film transistors. The oxygen flow can suppress the oxygen vacancy density, but introduce shallow states near the conduction edges. The electron can tunnel into gate oxide via these shallow states. As a result, the IGZO channel with oxygen flow has more electrons trapped in the gate oxide than the channel without oxygen flow, leading to more positive V T shift after positive bias temperature instability. The IGZO without oxygen flow create oxygen vacancy (VO) in the channel. The hole generated by impact ionization during the hot electron injection can be trapped in VO to form $\text{V}_{\text{O}}^{2+}$ . The $\text{V}_{\text{O}}^{2+}$ leads to less positive V T shift for IGZO channel without oxygen flow than with the oxygen flow. Since the impact ionization occurs near the drain, the positive $V_{T}$ shift of the reverse measurement (VSD > 0) is smaller than the forward measurement (VDS > 0) after hot electron injection.

Effects of oxygen flow on properties of La2Ti2O7−x films

In order to obtain the relationship between the properties and the oxygen flow rate of La2Ti2O7−x film, the films were prepared by electron beam evaporation with various oxygen flow rates on Si and quartz substrates. The effects of oxygen flow on the properties of La2Ti2O7−x film were analyzed by XRD, XPS, optical constant and laser damage test. The result shows that the La2Ti2O7−x film lose oxygen and lead to the transition of Ti4+ to Ti3+ in oxygen-free environment. When the oxygen flow rate is greater than 4 sccm, the content of Ti4+ is stable. The refractive index of La2Ti2O7−x films decreases with the increase of oxygen flow rate and stabilizes at oxygen flow rate greater than 4 sccm. The extinction coefficient of film deposited in oxygen-free environment is less than 10−4. As the oxygen flow rate increases, the film absorption is further improved to reach 10−5 at wavelengths longer than 350 nm. The laser damage threshold of films increased with increasing oxygen flow and the maximum value is 18.35 J cm−2.

The Effect of Oxygen Flow on the Transition Temperature of Hg0.75Pb0.25Sr2-yBayCa2Cu3O8+ δ Superconductors

In this paper, there are three different high temperature superconductors which are Hg0.75Pb0.25Sr2-y BayCa2Cu3O8+δ with deferent weight fractions y = 0.10, 0.20 and 0.25 that have been prepared successfully by solid state reaction and the samples have been equipped with/without O2 flow. The optimum calcinations is 1073 K and the sintering process that has been achieved within 1128-1133 K. Transition temperature Tc has been found by using four probe technique through electrical resistivity measurements. The greatest Tc that has been found for Hg0.75Pb0.25Sr1.75 Ba0.25Ca2Cu3O8.31 is 115 oK. Oxygen content (O2) flow exhibits high-phased superconductors that is similar to the samples prepared without O2. Investigation of X-ray diffraction (XRD) is revealed (tetragonal structure) by the c-axis lattice parameter increasing of the samples substituted with Ba. It has been established, from the calculated results, that the Ba variation concentrations of all samples products a modification in the density (ρm), (c/a) and volume fraction (VPh(2223)).

Effects of oxygen flows on optical properties, micro-structure and residual stress of Ta2O5 films deposited by DIBS

High precision optical components, such as ultra-high reflectors, severely suffer from absorption losses. In order to get optical films with low absorption losses, many techniques, such as annealing and laser conditioning, have been widely employed as a post-deposition treatment process to deal with as-deposited films. However, the success of these processes starts with the correct choice of the deposition parameters. In this paper, Ta2O5 films are deposited by dual ion beam sputtering (DIBS) method and the effects of target oxygen flows on optical properties, microstructure and residual stress are systematically investigated. The results show that target oxygen flows can significantly affect the absorption losses and residual stress of Ta2O5 film. The XRD patterns reveal that Ta2O5 films deposited at different parameters are all amorphous. Finally, based on the results of Ta2O5 films, broadband dielectric mirror with high reflection and low absorption losses in the range from 380 nm to 750 nm is successfully fabricated.

Effect of O2/Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO3 thin films deposited by RF sputtering at room temperature

SrTiO3 (STO) thin films have been prepared by reactive RF magnetron sputtering on Si (100) and UV fused silica substrates at room temperature. The effect of oxygen flow on film characteristics was investigated at a total gas flow of 30sccm, for various O2/O2+Ar flow rate ratios. As-deposited films were annealed at 700°C in oxygen atmosphere for 1h. Post-deposition annealing improved both film crystallinity and spectral transmittance. Film microstructure, along with optical and electrical properties, was evaluated for both as-deposited and annealed films. Abroad photoluminescence emission was observed within the spectral range of 2.75–3.50eV for all STO thin films irrespective of their deposition parameters. Upon annealing, the optical band gap of the film deposited with 0% O2 concentration slightly blue-shifted, while the other samples grown at higher oxygen partial pressure did not show any shift. Refractive indices (n) (at 550nm) were in the range of 2.05 to 2.09, and 2.10 to 2.12 for as-deposited and annealed films, respectively. Dielectric constant values (at 100kHz) within the range of 30–66 were obtained for film thicknesses less than 300nm, which decreased to ~30–38 after post-deposition annealing.

Oxygen Delivery Using a Neonatal Self-inflating Resuscitation Bag: Effect of Oxygen Flow

We evaluated the effect of oxygen (O₂) flow rate on the corresponding delivered fraction of oxygen (FiO₂) during positive pressure ventilation (PPV) when using a neonatal self-inflating bag (SIB). Fifteen health care professionals administered PPV at a respiratory rate of 40 to 60 breaths per minute and at peak inspiratory pressures of 25 and 35 cm H₂O to a manikin by using a SIB with reservoir connected to an O₂ source equipped with a flowmeter (flow rates: 0-10 L/min). The FiO₂ corresponding to each flow rate was measured at the inflow to the facial mask for 60 seconds. In total, 2520 FiO₂ data points were collected. At every O₂ flow rate, the FiO₂ gradually increased from time 0 seconds to time 60 seconds, both at 25 cm H₂O and at 35 cm H₂O. After 1 minute of PPV at 25 cm H₂O, the delivered FiO₂ was 31.5% ± 2.1% and 43.1% ± 3.1% at O₂ flow rates of 0.1 and 0.5 L/min, respectively. After 1 minute of PPV at 35 cm H₂O, the delivered FiO₂ was 29.4% ± 2.0% and 42.1% ± 4.6% at O₂ flow rates of 0.1 and 0.5 L/min, respectively. At all O₂ flow rates >5 L/min, the delivered FiO₂ was >85% and >95%, after 1 minute of PPV at 25 and 35 cm H₂O, respectively. Delivered FiO₂ during PPV depends on 3 factors: oxygen flow rate, peak inspiratory pressures, and time elapsed. These data can be used to develop a scheme correlating the oxygen flow rate and the corresponding delivered FiO₂ when using a neonatal SIB.

Oxygen Delivery Using a Neonatal Self-inflating Resuscitation Bag: Effect of Oxygen Flow

Oxygen Delivery Using a Neonatal Self-inflating Resuscitation Bag: Effect of Oxygen Flow

Investigation of ZnO thin films deposited on ferromagnetic metallic buffer layer by molecular beam epitaxy toward realization of ZnO-based magnetic tunneling junctions

Deposition of ZnO thin films on a ferromagnetic metallic buffer layer (Co3Pt) by molecular beam epitaxy technique was investigated for realization of ZnO-based magnetic tunneling junctions with good quality hexagonal ZnO films as tunnel barriers. For substrate temperature of 600 °C, ZnO films exhibited low oxygen defects and high electrical resistivity of 130 Ω cm. This value exceeded that of hexagonal ZnO films grown by sputtering technique, which are used as tunnel barriers in ZnO-MTJs. Also, the effect of oxygen flow during deposition on epitaxial growth conditions and Co3Pt surface oxidation was discussed.

Simulation and Parametric Analysis of Cryogenic Oxygen Plant for Biomass Gasification

Cryogenic air separation plants are used for production of oxygen, nitrogen and argon with required purity and recovery.The first grade oxygen (purity over 99.99%) is required for welding, cutting, and medical applications. These plants operate at low thermodynamic efficiency with specific power consumption in a range between 0.5-0.6 kw/scmh of O2. As air gasification produces poor quality syngas, oxygen is used as gasifying agent for biomass gasification. Medium purity cryogenic air separation units (ASU) are chiefly required for gasification. Biomass gasification with oxygen as gasifying agent has great potential in applications like integrated gasification combined cycle (IGCC), chemical production and Fischer-Tropsch (F-T) products. In this work simulation of medium purity oxygen cryogenic air separation plant integrated with biomass gasifier is carried out by using Aspen plus. Such cryogenic air separation plants which produce oxygen in a range between 85-98% can be used economically for gasification. The cryogenic oxygen plant produces oxygen with purity 96.2 % mole basis with specific power consumption as 0.2435 kw/scmh of O2. The performance parameters like recovery, purity, temperature and pressure and power consumption of cryogenic air separation unit are obtained. The parameters like syngas composition and heating value also predicted in simulation of biomass gasifier. The effect of parameters (parametric analysis), like vapour fraction of the feed on pure liquid (PL) flow and condenser duty, effect of number of stages on PL and rich liquid (RL) flow and its purity and effect of oxygen flow and gasifier temperature on syngas composition is discussed.

Effects of Oxygen Flow on the Infrared Switching Properties of Vanadium Oxide Thin Films

Vanadium oxide (VOX) thin films have been deposited on glass substrates with different oxygen flows (3, 3.2, and 3.6sccm) by means of magnetron sputtering process. We found that for different oxygen flows, the change of the infrared transmittance can be reached as high as 57%, the transmittance contrast factor can be reached as high as 88%,and the phase transition temperature is decreased to 54 oC, it is an ideal material for application in energy-efficient windows. According to the X-ray diffraction results of the thin films, we observed that with the increase of oxygen flow, VO2 (200) diffraction peak decreases obviously.

Effect of experimental conditions on parameters derived from TG-DSC measurements of low-temperature oxidation of coal

The process of oxygen chemisorption on coal in the temperature range ≈150–300 °C was studied under different experimental conditions using TG-DSC apparatus. As changing experimental conditions, oxygen flow (20 or 200 cm3 min−1), material of crucible (α-Al2O3 or Pt–Rh alloy), and initial sample mass (2–13 mg) were examined with respect to reliability and reproducibility of the parameters derived from TA curves. As parameters quantifying coal oxidation, temperatures of minimal Tmin and maximal Tmax sample mass, mass changes (mass loss WH below Tmin and mass increase WO above Tmin), heat evolution during oxygen chemisorption QO (related to the coal mass increase), and kinetic parameters (activation energy E and frequency factor A) were evaluated. Values of Tmax, E, and A were found to lie in very close intervals independently on experimental conditions (95% confidence intervals were Tmax = 270.2 ± 0.7 °C, E = 81 ± 3 kJ mol−1, log10A = 5.9 ± 0.3 s−1). Thus, these parameters can be used as actual characteristics of oxygen chemisorption stage of coal oxidation irrespective on conditions of TA measurements. Opposite, parameter QO was confirmed to depend clearly on initial sample mass. The dependence is different for crucible materials used; however, it tends to the same value (≈50 kJ g−1) with increasing sample mass. Further, precision of values WH, WO, and Tmin determined from TG was found to be poor. This fact complicates evaluation of the effect of experimental conditions. Finally, the effect of oxygen flow on all above parameters was found to be negligible. Its influence (if any) was hidden by common experimental errors.

Preparation and the light transmittance of TiO2 deposited fabrics

Nanoscale titanium dioxide (TiO2) films were deposited on the surface of polyester nonwovens by using direct current reactive magnetron sputtering. The effect of oxygen flow on the surface structures and properties of the fabrics was investigated in this article. The surface morphology, microstructure, and the chemical composition of TiO2-coated fibers were characterized by atomic force microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The effect of oxygen flow on deposition rate, white degree, and light transmission properties of the fabrics with nanoscale TiO2 films were examined. The test results proved that the oxygen flow was a key factor in sputter processing. The deposition speed decreased and the white degree of the fabric increased with increasing oxygen flow. The ultra-violet absorption by the polyester nonwoven fabric with TiO2 coatings was also enhanced as the oxygen flow increased in a proper range.

Structural and optical properties of direct current sputtered zinc aluminum oxides with a high Al concentration

Zinc aluminum oxide films were deposited by reactive dc magnetron sputtering from Zn/Al target containing 30 wt.% Al. Sputtering was carried out on glass and Si(100) substrates held at room temperature. The effect of oxygen flow on structural and optical properties was studied. The properties of the films were strongly dependent on oxygen flow. Amorphous, highly transparent and very smooth films were deposited in the oxidic mode while opaque and high surface roughness films were deposited in the metallic mode. The decrease in refractive index upon increasing oxygen flow is related to both the decrease in density as revealed by X-ray reflectometry and the increase in porosity. The band gaps obtained were in between the band gaps of Al 2O 3 and ZnO.

Effects of oxygen flow on the properties of indium tin oxide films

Indium tin oxide (ITO) films (In 2O 3–SnO 2) were deposited onto glass at different oxygen flow rates by RF magnetron sputtering method. Transmittance in visible light and an energy band gap were measured by ultraviolet spectrophotometer. Sheet resistance was measured by a four-point probe system. The thickness and complex refractive index of films were measured by spectroscopic ellipsometry. The component and the surface electron states of the ITO films were studied by XPS. The results indicated that the deposited ratio and refractive indexes of films were obviously affected by O 2 flow rate ( f O 2 ). The transmittance in visible light was beyond 80% (including glass substrate) with 60 nm film thickness and 9 sccm f O 2 . The transmittance and sheet resistance could be improved by heat treatment. XPS investigation showed that the photoelectrolytic properties could be deteriorated by the sub-oxides which could be reduced by f O 2 .