scholarly journals Transport Properties of Film and Bulk Sr0.98Zr0.95Y0.05O3−δ Membranes

2020 ◽  
Vol 10 (7) ◽  
pp. 2229 ◽  
Author(s):  
Adelya Khaliullina ◽  
Liliya Dunyushkina ◽  
Alexander Pankratov
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Transport Properties ◽  
Effective Conductivity ◽  
Ionic Transport ◽  
Transport Numbers ◽  
Pressure Gradients ◽  
Solution Deposition ◽  
Bulk Membrane ◽  
The Relationship

In electrode-supported solid oxide fuel cells (SOFCs) with a thin electrolyte, the electrolyte performance can be affected by its interaction with the electrode, therefore, it is particularly important to study the charge transport properties of thin electrode-supported electrolytes. The transport numbers of charged species in Ni-cermet supported Sr0.98Zr0.95Y0.05O3−δ (SZY) membranes were studied and compared to those of the bulk membrane. SZY films of 2.5 μm thickness were fabricated by the chemical solution deposition technique. It was shown that the surface layer of the films contained 1.5–2 at.% Ni due to Ni diffusion from the substrate. The Ni-cermet supported 2.5 μm-thick membrane operating in the fuel cell mode was found to possess the effective transport number of oxygen ions of 0.97 at 550 °C, close to that for the bulk SZY membrane (0.99). The high ionic transport numbers indicate that diffusional interaction between SZY films and Ni-cermet supporting electrodes does not entail electrolyte degradation. The relationship between SZY conductivity and oxygen partial pressure was derived from the data on effective conductivity and ionic transport numbers for the membrane operating under two different oxygen partial pressure gradients—in air/argon and air/hydrogen concentration cells.

scholarly journals Transport Processes in TlI and in the AgI-TlI-System

1974 ◽  
Vol 29 (5) ◽  
pp. 782-785
Author(s):  
A. Sdiiraldi ◽  
A. Magistris ◽  
E. Pezzati
Keyword(s):  
Electrical Conductivity ◽  
Transport Properties ◽  
Electronic Conductivity ◽  
Ionic Transport ◽  
Transport Processes ◽  
Silver Ion ◽  
Transport Numbers ◽  
Bond Ionicity ◽  
High Electronic Conductivity ◽  
High Silver

Abstract The transport properties of TlI and of the system AgI -TlI were investigated by measuring the electrical conductivity, σ , and the electronic and ionic transport numbers. A particularly high electronic conductivity was detected in β-TlI, while the a phase showed a predominant anionic contribution, as in TlCl and TlBr. The intermediate compounds, AgTl2I3 and AgTlI2, are silver ion conductors, but they exhibit low σ values. A comparison with other poliiodides, with a high silver ion conductivity, is suggested on the basis of the crystal bond ionicity.

Ionic transport in LiNbO3

1991 ◽  
Vol 6 (4) ◽  
pp. 851-854 ◽  
Author(s):  
Apurva Mehta ◽  
Edward K. Chang ◽  
Donald M. Smyth
Keyword(s):  
Ionic Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ionic Transport ◽  
Ionic Transport Number ◽  
Cell Measurement ◽  
Experimental Validity ◽  
Pressure Independent ◽  
Temperature Equilibrium ◽  
Good Agreement

The high temperature equilibrium conductivity (950 °C–1050 °C) of congruent LiNbO3 can be resolved into two components: an electronic portion that is dependent on the oxygen partial pressure and an ionic portion that is pressure independent. It is shown that the two components can be obtained from an analysis of the total equilibrium conductivity measured as a function of oxygen partial pressure. The ionic transport number (fractional ionic conductivity) thus obtained is compared with that obtained from an oxygen concentration cell measurement. The two techniques are found to be in excellent agreement, confirming the experimental validity of the defect chemistry method. From the temperature dependence of the ionic conductivity, the activation energy (138 kJ/mol [1.43 eV]) for the ionic transport is obtained. The results are in good agreement with the value previously obtained for the oxygen chemical diffusivity.

THE ELECTRICAL PROPERTIES OF ALUMINA AT HIGH TEMPERATURES

1966 ◽  
Vol 44 (8) ◽  
pp. 1685-1698 ◽  
Author(s):  
T. Matsumura
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystal ◽  
Transport Number ◽  
Ionic Transport ◽  
Mixed Conductor ◽  
Polycrystalline Alumina ◽  
Ionic Transport Number

The ionic transport number and the d-c. electrical conductivity of single-crystal and polycrystalline alumina have been studied between 1 000 °K and 1 750 °K at an oxygen partial pressure of 0.2 atm. The ionic transport number was determined by the galvanic-cell e.m.f. measurements; the electrical conductivity was measured by the three-terminal method.It was found that alumina is a mixed conductor, being predominantly an ionic conductor at temperatures below 1 100 °K and predominantly electronic at temperatures higher than 1 600 °K. The activation energies found for the electrical conductivity of the single-crystal and polycrystalline specimens are 0.8 eV and 2.4 eV respectively in the ionic range and 3.0 eV and 3.7 eV in the electronic range.

Oxygen potentials of PuO2-x

2012 ◽  
Vol 1444 ◽  
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.

Oxygen Transport Kinetics in La0.5Sro0.5Fe0.8Ga0.2O3−δ Membranes Under Both Small and Large Oxygen Partial Pressure Gradients

1998 ◽  
Vol 548 ◽  
Author(s):  
Sangtae Kim ◽  
Allan J. Jacobson ◽  
Benjamin Abeles
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Transport ◽  
Oxygen Flow Rate ◽  
Pressure Gradients ◽  
Exchange Coefficient ◽  
Maximum Enhancement ◽  
Surface Exchange ◽  
Surface Exchange Coefficient

ABSTRACTOxygen permeation through a new perovskite La0.5Sr0.5Fe0.8Ga0.2O3−δ membrane has been measured both under small (air/He) and large (air/CO, CO2) oxygen partial pressure gradients. In both cases oxygen transport is close to surface limited. By modeling the pressure dependence of the oxygen flow rate under small pressure gradient an ambipolar diffusion coefficient 9.65 × 10−7cm2/s and a surface exchange coefficient 7.15 × 10−6 cm/s at 974 °C were determined. With air/CO, CO2 on the permeate side, the permeability increases linearly with the partial pressure of CO. The observed increase is greater than the maximum enhancement predicted by our model.

scholarly journals A Thermodynamic Analysis on the Roasting of Pyrite

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 220 ◽  
Author(s):  
Yan Zhang ◽  
Qian Li ◽  
Xiaoliang Liu ◽  
Bin Xu ◽  
Yongbin Yang ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Iron Oxides ◽  
Thermodynamic Analysis ◽  
Inert Atmosphere ◽  
Thermodynamic Calculations ◽  
Oxidizing Atmosphere ◽  
Low Levels ◽  
Iron Sulphates ◽  
The Relationship

A series of thermodynamic calculations are performed for the roasting of pyrite in changing temperatures and atmospheres. The relationship between ΔrGθ and temperature in the range of T = 300–1200 K shows that, depending on the atmosphere it is in, reactions of pyrolysis, oxidation or reduction can occur. Both the pyrolysis of pyrite in an inert atmosphere and its oxidation by oxygen can form pyrrhotite (mainly Fe0.875S and FeS), but the temperature required for oxidation is much lower than that for pyrolysis. In an oxygen-containing atmosphere, the isothermal predominance areas for the Fe–S–O system indicate that a change in temperature and oxygen partial pressure can lead the pyrite to undergo desulphurization to pyrrhotite (FeS2 → Fe0.875S/FeS) or iron oxides (FeS2 → Fe3O4/Fe2O3), or sulphation to iron sulphates (FeS2 → FeSO4/Fe2(SO4)3). The presence of carbon is beneficial to the desulphurization of pyrite under an oxidizing atmosphere since iron sulphates can be converted to iron oxides at very low levels of PCO/PCO2. Results presented in this paper offer theoretical guidance for the optimization of roasting of pyrite for different purposes.

Undergraduate students' misconceptions about respiratory physiology.

1999 ◽  
Vol 277 (6) ◽  
pp. S127 ◽  
Author(s):  
J A Michael ◽  
D Richardson ◽  
A Rovick ◽  
H Modell ◽  
D Bruce ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Undergraduate Students ◽  
Liberal Arts ◽  
Minute Ventilation ◽  
Respiratory Physiology ◽  
Carbon Dioxide Partial Pressure ◽  
Arterial Oxygen ◽  
Physiological Variables ◽  
The Relationship

Approximately 700 undergraduates studying physiology at community colleges, a liberal arts college, and universities were surveyed to determine the prevalence of our misconceptions about respiratory phenomena. A misconception about the changes in breathing frequency and tidal volume (physiological variables whose changes can be directly sensed) that result in increased minute ventilation was found to be present in this population with comparable prevalence (approximately 60%) to that seen in a previous study. Three other misconceptions involving phenomena that cannot be experienced directly and therefore were most likely learned in some educational setting were found to be of varying prevalence. Nearly 90% of the students exhibited a misconception about the relationship between arterial oxygen partial pressure and hemoglobin saturation. Sixty-six percent of the students believed that increasing alveolar oxygen partial pressure leads to a decrease in alveolar carbon dioxide partial pressure. Nearly 33% of the population misunderstood the relationship between metabolism and ventilation. The possible origins of these respiratory misconceptions are discussed and suggestions for how to prevent and/or remediate them are proposed.

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