Accelerated ceria–zirconia solubilization by cationic diffusion inversion at low oxygen activity

2016 ◽  
Vol 4 (43) ◽  
pp. 16871-16878 ◽  
Author(s):  
Vincenzo Esposito ◽  
De Wei Ni ◽  
Debora Marani ◽  
Francesca Teocoli ◽  
Karl Tor Sune Thydén ◽  
...  
Keyword(s):  
High Temperatures ◽  
Oxygen Activity ◽  
Doped Ceria ◽  
Low Oxygen ◽  
Stabilized Zirconia ◽  
Reducing Conditions ◽  
Elemental Diffusion

Fast elemental diffusion at the Gd-doped ceria/Y-stabilized zirconia interface occurs under reducing conditions at low oxygen activity and high temperatures.

scholarly journals Is Reduced Strontium Titanate a Semiconductor or a Metal?

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 744
Author(s):  
Christian Rodenbücher ◽  
Christo Guguschev ◽  
Carsten Korte ◽  
Sebastian Bette ◽  
Kristof Szot
Keyword(s):  
Point Defect ◽  
Decisive Role ◽  
Thermal Reduction ◽  
Defect Chemistry ◽  
Oxygen Activity ◽  
Metallic State ◽  
Metallic Behavior ◽  
Reducing Conditions ◽  
History Play ◽  
Semiconducting Behavior

In recent decades, the behavior of SrTiO3 upon annealing in reducing conditions has been under intense academic scrutiny. Classically, its conductivity can be described using point defect chemistry and predicting n-type or p-type semiconducting behavior depending on oxygen activity. In contrast, many examples of metallic behavior induced by thermal reduction have recently appeared in the literature, challenging this established understanding. In this study, we aim to resolve this contradiction by demonstrating that an initially insulating, as-received SrTiO3 single crystal can indeed be reduced to a metallic state, and is even stable against room temperature reoxidation. However, once the sample has been oxidized at a high temperature, subsequent reduction can no longer be used to induce metallic behavior, but semiconducting behavior in agreement with the predictions of point defect chemistry is observed. Our results indicate that the dislocation-rich surface layer plays a decisive role and that its local chemical composition can be changed depending on annealing conditions. This reveals that the prediction of the macroscopic electronic properties of SrTiO3 is a highly complex task, and not only the current temperature and oxygen activity but also the redox history play an important role.

Non-Stoichiometry and Cation Tracer Diffusion Studies in the Magnetite-UlvÖSpinel Solution, (Fe,Ti)3-δO4

1994 ◽  
Vol 369 ◽  
Author(s):  
Sanjeev Aggarwal ◽  
Rudiger Dieckmann
Keyword(s):  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Oxygen Activity ◽  
Spinel Solid Solution ◽  
Low Oxygen ◽  
Cation Diffusion ◽  
Deviation From Stoichiometry ◽  
Diffusion Studies ◽  
Tracer Diffusion Coefficients ◽  
Point Defect Structure

AbstractCation diffusion in the spinel solid solution (Fe1-xTix)3-δO4 (0≤ x ≤ 0.3) was investigated at 1200 ºC as a function of oxygen activity, aO2 and cationic composition, x. At different cationic compositions, cation tracer diffusion coefficients, D*Me of Me = Fe and Ti were measured as a function of oxygen activity. Plots of log DMe vs. loga0 show V-shaped curves, indicating that different types of point defects prevail at high anc low oxygen activities. Thermogravimetric experiments were conducted, using a high resolution microbalance, to determine the deviation from stoichiometry in (Fe1-xTix)3-δO4 at 1200 °C. δversus log aO2 curves are S-shaped. An analysis of the oxygen activity dependences of thecation diffusion coefficients and the deviation from stoichiometry with regardto the point defect structure suggests that at high oxygen activities cation vacancies are the predominant defects governing the deviation from stoichiometry and the diffusion ofcations. At low oxygen activities, and at small values of x, cation interstitials determine the deviation from stoichiometry, while they dominate for 0 ≤ x ≤ 0.3 inthe cation diffusion.

Superplastic Flow in 3 mol % Yttria-Stabilized Zirconia at High Temperatures

2001 ◽  
Vol 206-213 ◽  
pp. 1013-1016 ◽  
Author(s):  
Marek Boniecki ◽  
Zdzislaw Librant ◽  
Andrzej Gładki ◽  
Helena Węglarz ◽  
Władysław Wesołowski
Keyword(s):  
High Temperatures ◽  
Superplastic Flow ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia

Epitaxial pore-free gadolinia-doped ceria thin films on yttria-stabilized zirconia by RF magnetron sputtering

2013 ◽  
Vol 39 (8) ◽  
pp. 9749-9752 ◽  
Author(s):  
Haris M. Ansari ◽  
Michael D. Rauscher ◽  
Suliman A. Dregia ◽  
Sheikh A. Akbar
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Rf Magnetron Sputtering ◽  
Yttria Stabilized Zirconia ◽  
Doped Ceria ◽  
Stabilized Zirconia
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