The Oxygen Defect Chemistry of La2−xSrxCuO4−x/2+δ

1990 ◽  
Vol 209 ◽  
Author(s):  
Elizabeth J. Opila ◽  
Harry L. Tuller
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Content ◽  
Defect Chemistry ◽  
Oxygen Stoichiometry ◽  
Oxygen Defect ◽  
Defect Model ◽  
Strontium Concentration ◽  
Partial Pressures ◽  
Equilibrium Oxygen

ABSTRACTThe equilibrium oxygen stoichiometry of La2−xSrxCuO4±y (x=O, 0.2, 0.4, and 1.0) has been determined by TGA at temperatures between 800 and 1050°C and oxygen partial pressures between 1 and 10−4 atmospheres. The changes in oxygen content with temperature, oxygen partial pressure, and strontium concentration are evaluated in terms of a defect model.

Electrical Conductivity Prediction in Langasite for Optimized Microbalance Performance at Elevated Temperatures

2002 ◽  
Vol 756 ◽  
Author(s):  
Huankiat Seh ◽  
Harry Tuller ◽  
Holger Fritze
Keyword(s):  
Electrical Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
High Temperatures ◽  
Gas Sensors ◽  
Elevated Temperatures ◽  
Operating Conditions ◽  
Total Conductivity ◽  
Defect Model ◽  
Partial Pressures

ABSTRACTThe performance of the langasite-based crystal microbalance is limited due to reductions in its resistivity at high temperatures and reduced oxygen partial pressures. In this work, we utilize a recently developed defect model to predict the dependence of the ionic and electronic contributions to the total conductivity of langasite on temperature, oxygen partial pressure and acceptor and donor dopants. These results are used to select the type and concentrations of dopants expected to provide extended operating conditions for langasite-based gas sensors and crystal microbalances.

Some Aspects of the Nonstoichiometric and Thermodynamic Behavior of the YBa2Cu3Oz System

1989 ◽  
Vol 156 ◽  
Author(s):  
M. Tetenbaum ◽  
L. Curtiss ◽  
B. Czech ◽  
B. Tani ◽  
M. Blander
Keyword(s):  
Low Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Coulometric Titration ◽  
Temperature Data ◽  
Oxygen Stoichiometry ◽  
Miscibility Gap ◽  
Thermodynamic Behavior ◽  
Partial Pressures ◽  
Titration Technique

ABSTRACTThe nonstoichiometric and thermodynamic behavior of the YBa2Cu3Ox system as a function of oxygen partial pressure and temperature is being investigated by means of a coulometric titration technique. The oxygen content of the superconductor can be varied coulometrically by well-defined small amounts and the equilibrium partial pressures determined from the EMF. The oxygen stoichiometry in YBa2Cu3Ox as a function of oxygen partial pressure shows a change of curvature around x = 6.55–6.75 and an inflection around x ≅ 6.65 at temperatures between 400–500°C. These new low temperature data are consistent with the presence of a miscibility gap at lower temperatures, which is similar to that postulated in several theoretical papers.

Impact of oxygen content on preferred localization of p- and n-type carriers in La0.5Sr0.5Fe1−xMnxO3−δ

2021 ◽  
Author(s):  
Sergey S. Nikitin ◽  
Alexey A. Markov ◽  
Oleg V. Merkulov ◽  
Andrey V Chukin ◽  
Mikhail Patrakeev
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Content ◽  
Coulometric Titration ◽  
Defect Chemistry ◽  
Wide Range

The oxygen content in La0.5Sr0.5Fe1−xMnxO3−δ, measured by coulometric titration in a wide range of oxygen partial pressure at various temperatures, was used for defect chemistry analysis. The obtained data were...

Recrystallization of Oxygen Contaminated Al Films

1986 ◽  
Vol 71 ◽  
Author(s):  
G.J. Van Der Kolk ◽  
M.J. Verkerk
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Relative Increase ◽  
Partial Pressures ◽  
Average Grain Size

AbstractAl was evaporated at oxygen partial pressures, PO2, varying between 10−7 and 10−4 Pa on substrates of silicon nitride. The substrate temperature was varied between 20 °C and 250°C. The films were annealed at temperatures up to 500°C.For Al films deposited at 20°C, it was found that the average grain size decreases with increasing oxygen partial pressure. After annealing recrystallization was observed. The relative increase of grain size was less for higher values of pO2. Annealing gave rise to a broad grain size distribution.For Al films deposited at 250°C, the presence of oxygen caused the growth of rough inhomogeneous films. This inhomogeneous structure remained during annealing.

Controlled partial melting during isobaric and isothermal processing of dipcoated Bi-2212/Ag tapes

1998 ◽  
Vol 13 (12) ◽  
pp. 3580-3586 ◽  
Author(s):  
A. L. Crossley ◽  
J. L. MacManus-Driscoll
Keyword(s):  
Phase Diagram ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Partial Melting ◽  
Coulometric Titration ◽  
Processing Route ◽  
Optimum Processing ◽  
Partial Pressures ◽  
Titration Technique

A detailed study has been made of the control and optimization of partial melting of dipcoated Bi2Sr2Ca1Cu2O8+δAg0.1 (Bi-2212) tapes using reduced oxygen partial pressures. A coulometric titration technique has been employed to vary the oxygen partial pressure in a region of the phase diagram corresponding to binary melting, and the amount of partial melting has been quantified. Using this information, tapes have been processed using both isothermal and isobaric techniques. An optimum processing route was determined which combined isothermal and isobaric processes. Highly aligned material at the point of optimum melting was obtained.

Tensile Properties and Creep Behavior of SiC-Based Fibers under Various Oxygen Partial Pressures

2005 ◽  
Vol 475-479 ◽  
pp. 1333-1336 ◽  
Author(s):  
Jan Ji Sha ◽  
J.S. Park ◽  
Tatsuya Hinoki ◽  
Akira Kohyama ◽  
J. Yu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Tensile Properties ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Sic Fibers ◽  
Partial Pressures ◽  
Ar Gas

Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxygen partial pressures were applied to investigate the tensile properties and creep behavior of SiC fibers such as Hi-NicalonTM and TyrannoTM-SA. These fibers were annealed and crept at elevated temperatures ranging from1273-1773 K in such environments. After annealing at 1773 K, the room temperature tensile strengths of SiC-based fibers decreased with decreasing the oxygen partial pressure and the near stoichiometric fiber TyrannoTM-SA shows excellent strength retention. At temperatures above the 1573 K, the creep resistance of SiC fibers evaluated by bending stress relaxation (BSR) method under high oxygen partial pressure was lower than that of in low oxygen partial pressure. The microstructural features on these fibers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Über die Instabilität von NiTiO3 unter der Wirkung eines Sauerstoffpartialdruck-Gradienten Instability of NiTiO3 in an Oxygen-Potential Gradient

1981 ◽  
Vol 36 (10) ◽  
pp. 1211-1214 ◽  
Author(s):  
W. Laqua
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Potential ◽  
Potential Gradient ◽  
Simultaneous Action ◽  
Partial Pressures ◽  
Quantitative Explanation

Abstract If a NiTiO3 poly crystal is exposed to an oxygen-potential gradient -established by the simultaneous action of two different oxygen partial pressures -it will be decomposed into its component oxides NiO and TiO2 despite the fact, that the compound is stable at both the lower and the higher oxygen partial pressure. A quantitative explanation of this phenomenon will be given below.

Thermodynamic analysis of oxidation during selective laser melting of pure titanium

2020 ◽  
Vol 26 (8) ◽  
pp. 1401-1404
Author(s):  
Won-Hyuk Lee ◽  
Tae-Wook Na ◽  
Kyung-Woo Yi ◽  
Seung-Min Yang ◽  
Jang-Won Kang ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Oxidation Behavior ◽  
Pure Titanium ◽  
Initial Powder ◽  
Laser Melting ◽  
Content Type ◽  
Equilibrium Oxygen ◽  
Equilibrium Oxygen Partial Pressure

Purpose When a pure titanium component is fabricated in a selective laser melting (SLM) process using titanium powder, the oxygen concentration of the SLM sample increases compared to the initial powder. The purpose of this paper is to study the reason for increasing oxygen concentration after SLM. Design/methodology/approach To understand this phenomenon, the authors analyzed the oxidation behavior during the SLM process thermodynamically. Findings Based on the laser parameters used in this study, the temperature of the Ti melt during the SLM process was expected to rise to 2,150°C. Based on the thermodynamic analysis, the equilibrium oxygen partial pressure for oxidation was 2.32 × 10−19 atm at 2,150°C when the dissolved oxygen concentration in the titanium is 0.2 wt.%. However, the oxygen partial pressure inside the SLM chamber was 1 × 10−3 atm, which is much higher than the equilibrium oxygen partial pressure. Therefore, oxidation occurred during the SLM process, and the oxygen concentration of the SLM sample increased compared to the initial powder. Originality/value Most studies on fabricating Ti components using additive manufacturing (AM) have been focused on how the changes in the microstructures and mechanical properties depend on the process parameters. However, there are a few studies that analyzed the oxygen concentration change of Ti during the AM process and its causes. In this study, the authors analyzed the oxidation behavior during the SLM process thermodynamically.

Defect chemistry of donor-doped BaTiO3 with BaO-excess for reduction resistant PTCR thermistor applications – redox-behaviour

2020 ◽  
Vol 22 (15) ◽  
pp. 8219-8232
Author(s):  
Christian Pithan ◽  
Hayato Katsu ◽  
Rainer Waser
Keyword(s):  
Electrical Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Defect Chemistry ◽  
Redox Behaviour ◽  
Ptcr Effect

The electrical conductivity of donor-doped BaTiO3 thermistor ceramics with excessive BaO revealing a reduction-persistent PTCR effect has been carefully examined depending on materials’ composition and oxygen partial pressure at moderate temperatures between 973 and 1273 K.

scholarly journals Oxygen separation from air by the combined temperature swing and pressure swing processes using oxygen storage materials Y1−x(Tb/Ce)xMnO3+δ

2020 ◽  
Vol 55 (33) ◽  
pp. 15653-15666
Author(s):  
Alicja Klimkowicz ◽  
Takao Hashizume ◽  
Kacper Cichy ◽  
Sayaka Tamura ◽  
Konrad Świerczek ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Content ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Oxygen Separation ◽  
Storage Materials ◽  
Temperature Swing ◽  
Pressure Swing

Abstract Hexagonal Y1−xRxMnO3+δ (R: other than Y rare earth elements) oxides have been recently introduced as promising oxygen storage materials that can be utilized in the temperature swing processes for the oxygen separation and air enrichment. In the present work, the average and local structures of Tb- and Ce-substituted Y0.7Tb0.15Ce0.15MnO3+δ and Y0.6Tb0.2Ce0.2MnO3+δ materials were studied, and their oxygen storage-related properties have been evaluated. The fully oxidized samples show the presence of a significant amount of the highly oxygen-loaded the so-called Hex3 phase, attaining an average oxygen content of δ ≈ 0.41 for both compositions. Extensive studies of the temperature swing process conducted in air and N2 over the temperature range of 180–360 °C revealed large and reversible oxygen content changes taking place with only a small temperature differences and the high dependence on the oxygen partial pressure. Significant for practical performance, the highest reported for this class of compounds, oxygen storage capacity of 1900 μmol O g−1 in air was obtained for the optimized materials and swing process. In the combined temperature–oxygen partial pressure swing process, the oxygen storage capacity of 1200 μmol O g−1 was achieved.

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