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

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.

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

Journal of Materials Research ◽

10.1557/jmr.1998.0487 ◽

1998 ◽

Vol 13 (12) ◽

pp. 3580-3586 ◽

Cited By ~ 3

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.

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Examples of the Practical Use of Non-Stoichiometric Compounds

Chemistry of Non-stoichiometric Compounds ◽

10.1093/oso/9780198555551.003.0006 ◽

1994 ◽

Author(s):

Koji Kosuge

Keyword(s):

Solid State ◽

Oxygen Partial Pressure ◽

Partial Pressure ◽

Oxygen Pressure ◽

Closed System ◽

Electromotive Force ◽

Solid Electrolytes ◽

Coulometric Titration ◽

Preparation Methods ◽

Basic Characteristics

In this chapter, we describe four kinds of non-stoichiometric compound, which are or will be in practical use, from the viewpoint of preparation methods or utility. As a first example, the solid electrolyte (ZrO2)0.85(CaO)0.15 is described, which are discussed in Sections 1.4.6–1.4.8 from the viewpoint of basic characteristics. The second example is the magnetic material Mn–Zn ferrite, for which the control of non-stoichiometry and the manufacturing process will be described. Then the metal hydrides or hydrogen absorbing alloys, which are one of the most promising materials for storing and transporting hydrogen in the solid state, are described, mainly focusing on the phase relation. Finally, we describe the relation between the control of composition and the growth of a single crystal of the semiconductive compound GaAs, which is expected to give electronic materials for 1C and LSI etc. Solid electrolytes, which show ionic conductivity in the solid state, are considered to be potential materials for practical use, some are already used as mentioned below. Solid electrolytes have characteristic functions, such as electromotive force, ion selective transmission, and ion omnipresence. Here we describe the practical use of calcia stabilized zirconia (CSZ), (ZrO2)0.85(CaO)0.15, the structure and basic properties of which are discussed in detail in Sections 1.4.5–1.4.8. The most simple practical application of CSZ is for the gauge of oxygen partial pressure, as mentioned in Sections 1.4.7 and 1.4.8. The oxygen partial pressure P2o2 in the closed system as shown in Fig. 3.1 can be measured, taking the air as the standard oxygen pressure P1o2. The electromotive force (EMF) of this concentration cell is expressed as . . . E = (RT/4F)ln(P1o2/ P2o2) . . . This principle is applied in the measurement of oxygen partial pressure in laboratory experiments and of the oxygen activity of slag in refineries. Based on the principle of coulometric titration (see Section 1.4.8), the oxygen partial pressure of a closed system can be kept constant by feedback of the EMF, in the oxygen pressure range 1 to 10−7 atm. By use of this closed system, investigations on redox reactions of metals and also enzyme reactions have been carried out.

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

Physical Chemistry Chemical Physics ◽

10.1039/c9cp06793k ◽

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.

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

Journal of Materials Science ◽

10.1007/s10853-020-05158-5 ◽

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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ChemInform Abstract: Influence of Oxygen Partial Pressure and Oxygen Content on the Wettability in the Copper-Oxygen-Alumina System.

ChemInform ◽

10.1002/chin.200004019 ◽

2010 ◽

Vol 31 (4) ◽

pp. no-no

Author(s):

Matthias Diemer ◽

Achim Neubrand ◽

Kevin P. Trumble ◽

Juergen Roedel

Keyword(s):

Oxygen Partial Pressure ◽

Partial Pressure ◽

Oxygen Content

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How to Optimize Critical Current Performance of RE123 Materials by Controlling Oxygen Content

MRS Proceedings ◽

10.1557/proc-689-e8.18 ◽

2001 ◽

Vol 689 ◽

Cited By ~ 9

Author(s):

Jun-ichi Shimoyama ◽

Shigeru Horii ◽

Kenji Otzschi ◽

Kohji Kishio

Keyword(s):

Oxygen Partial Pressure ◽

Partial Pressure ◽

Critical Current ◽

Oxygen Content ◽

Oxygen Nonstoichiometry ◽

Thermodynamic Quantities ◽

Precise Control ◽

Oxygen Defects ◽

Re Elements ◽

Selection Of

ABSTRACTOxygen nonstoichiometry behaviors of REBa2Cu3Oy (RE123: RE= Nd, Sm, Eu, Gd, Dy. Ho and Y) compounds have been precisely determined by the thermogravimetric measurements. Dependence of oxygen content on temperature and oxygen partial pressure were found to slightly depend on the RE element. Thermodynamic quantities of oxygen, such as hO2 and sO2, also varied with RE element. Relationship between Tc and oxygen content is strongly dependent on the RE species. This suggests that pinnig effect due to the oxygen defects is different in each RE123 compound and, therefore, critical current properties of RE123 must be optimized by precise control of oxygen content as well as selection of suitable RE elements.

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Oxygen potentials of PuO2-x

MRS Proceedings ◽

10.1557/opl.2012.1162 ◽

2012 ◽

Vol 1444 ◽

Cited By ~ 4

Author(s):

Akira Komeno ◽

Masato Kato ◽

Shun Hirooka ◽

Takeo Sunaoshi

Keyword(s):

Oxygen Partial Pressure ◽

Partial Pressure ◽

Measurement Data ◽

Approximate Equation ◽

Defect Chemistry ◽

Thermo Gravimetry ◽

Metal Ratio ◽

The Relationship

ABSTRACTOxygen potentials of PuO2-x were measured at temperatures of 1473 - 1873 K by thermo-gravimetry. The oxygen potentials were determined by in situ analysis as functions of oxygen-to-metal ratio and temperature. The measurement data were analyzed on the basis of defect chemistry and an approximate equation was derived to represent the relationship among temperature, oxygen partial pressure, and deviation x in PuO2-x.

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

MRS Proceedings ◽

10.1557/proc-156-83 ◽

1989 ◽

Vol 156 ◽

Cited By ~ 4

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.

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