Oxygen Stoichiometry in La0.6Sr0.4CoO3−δand La0.6Sr0.4Co0.2Fe0.8O3−δCathodes under Applied Potential as a Function of Temperature and Oxygen Partial Pressure, Measured by Electrochemical in Situ High-Temperature XRD Method

2013 ◽  
Vol 160 (9) ◽  
pp. F1022-F1026 ◽  
Author(s):  
I. Kivi ◽  
J. Aruväli ◽  
K. Kirsimäe ◽  
A. Heinsaar ◽  
G. Nurk ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Stoichiometry ◽  
Applied Potential ◽  
High Temperature Xrd ◽  
Xrd Method

Characterization of YBa2Cu4O8 high temperature electrical properties and thermodynamic stability

1991 ◽  
Vol 6 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
B-S. Hong ◽  
T.O. Mason
Keyword(s):  
High Temperature ◽  
Electrical Property ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Stability Range

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500–800 °C and oxygen partial pressure range 10−4-1 atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu4O8 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu3O6+y (or YBa2Cu3.5O7.5±z) and CuO occurs at log(po2, atm) = −1.24 × 104/T(K) + 11.01(773 ⋚ T(K) ⋚ 1073).

Controlling Defects in Double-Layer Cuprates by Chemical Modifications

1996 ◽  
Vol 453 ◽  
Author(s):  
P. A Salvador ◽  
K. B. Greenwood ◽  
K. Otzschi ◽  
J. W Koenitzer ◽  
B. M. Dabrowski ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Transport Properties ◽  
Elevated Temperatures ◽  
Double Perovskite ◽  
Chemical Modifications ◽  
Active Layers

AbstractIn-situ high temperature electrical conductivity and thermopower have been measured simultaneously on a number of ordered perovskite-like oxides containing double CUO4/2 sheets. Equilibrium measurements have been conducted as a function of oxygen partial pressure, temperature and chemical substitution in order to understand the relationships between the chemical architecture and the transport and defect properties. Data for LaBa2Cu2NbO8 and LaCa2Cu2GaO7 are presented and compared with those of known triple perovskite superconductors, Y1−xCaxSr2Cu2GaO7 and YBa2Cu3O7−δ, and several quadruple perovskites, Ln′Ln″Ba2Cu2M2O11 (Ln = Lanthanide, Y; M = Sn, Ti). These materials belong to a general family of superconductors which are constructed from similar ‘active’ layers (double perovskite blocks of square-pyramidal copper-oxygen sheets), and interleaved with fixed valence cations in perovskite-like ‘conditioning’ layers. Similarities in the transport properties of the non-superconducting and superconducting materials at elevated temperatures are illustrated, and the amount and types of defects, including carrier concentrations, are correlated with the internal chemistry and inner architecture of each material.

In Situ XRD Study of Zirconia Phase Transformation Produced from Chemical and Mineral Processes

2016 ◽  
Vol 840 ◽  
pp. 375-380
Author(s):  
Meor Yusoff Meor Sulaiman ◽  
Khaironie Mohamed Takip ◽  
Ahmad Khairulikram Zahari
Keyword(s):  
High Temperature ◽  
Heating Temperature ◽  
Tetragonal Zirconia ◽  
Amorphous Structure ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Zirconyl Chloride ◽  
High Temperature Xrd ◽  
Temperature Phase Transition

The high temperature phase transition of zirconia produced from commercial zirconyl chloride chemical was compared with that produced from a Malaysian zircon mineral. Zirconyl chloride was produced from zircon by using the hydrothermal fusion method. Initial XRD diffractogram of these samples at room temperature show that they are of amorphous structure. High temperature XRD studies was then performed on these samples; heated up to 1500°C. The XRD diffractograms shows that the crystalline structure of tetragonal zirconia was first observed and the monoclinic zirconia becomes more visible at higher heating temperature.

Influences of oxygen impurity contained in nitrogen gas on the reactions of chromium with nitrogen

2005 ◽  
Vol 20 (10) ◽  
pp. 2745-2753 ◽  
Author(s):  
Yung-Shou Ho ◽  
Fong-Shung Huang ◽  
Fu-Hsing Lu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Impurity ◽  
Nitrogen Gas ◽  
Available Nitrogen ◽  
Increasing Temperature ◽  
Pressure Changes ◽  
Annealing Experiments ◽  
Simultaneous Dissolution

In this research, the influences of the oxygen impurity contained in the commercially available nitrogen gas on the reactions of chromium pellets with nitrogen were investigated in the temperature range 600–1350 °C. A small amount of oxygen competed with the majority N2 to react with chromium in the annealing process. Analyzing the in situ oxygen partial pressure changes during annealing proved that the dissolution of oxygen in Cr and/or resultant CrxN (CrN or Cr2N) was exothermic and the solubility decreased with increasing temperature. It was found that the oxygen partial pressure decreased drastically to about 10−22 atm when specimens were annealed at 600 °C compared to a mere 10−5 atm for a blank test, while its value increased with temperature. The oxidation involved simultaneous dissolution of oxygen in specimens and formation of oxide scale. Moreover, comparing the aforementioned results with those obtained from additional annealing experiments preformed in argon gas showed that the formation of Cr2O3 might stem mainly from oxidation of the resultant nitrides instead of the metallic chromium.

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