Mathematical Modeling of Oxygen Exchange and Transport in Air‐Perovskite‐Yttria‐Stabilized Zirconia Interface Regions: II. Direct Exchange of Oxygen Vacancies

1998 ◽  
Vol 145 (4) ◽  
pp. 1390-1400 ◽  
Author(s):  
Ann Mari Svensson ◽  
Svein Sunde ◽  
Kemal Nis¸ancioǦlu
Author(s):  
Hong Shen ◽  
Juan Jiang ◽  
Decai Feng ◽  
Chen Xing ◽  
Xiaofeng Zhao ◽  
...  

The crack behaviors of yttrium-stabilized zirconia during laser drilling in air, vacuum, and water environments were investigated. Due to the high stress and low fracture toughness induced by tetragonal-monoclinic phase transformation, tremendous cracks occur during drilling in air. Contrastly, cracks were reduced in vacuum drilling since the phase transformation was suppressed due to the generation of oxygen vacancies. By protection of water, no cracks were observed due to low stress and maintained fracture toughness. The crack mechanisms in different drilling media were discussed.


2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Maxime Lortie ◽  
Rima J. Isaifan

Cu50Ni50 nanoparticles were synthesized using a modified polyol method and deposited on samarium-doped ceria, SDC, and yttria-stabilized zirconia, YSZ, supports to form reverse water-gas shift, RWGS, catalysts. The best CO yields, obtained with the Cu50Ni50/SDC catalyst, were about 90% of the equilibrium CO yields. In contrast CO yields using Pt/SDC catalysts were equal to equilibrium CO yields at 700°C. Catalyst selectivity to CO was 100% at hydrogen partial pressures equal to CO2 partial pressures, 1 kPa, and decreased as methane was formed when the hydrogen partial pressure was 2 kPa or greater. The reaction results were explained using a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms that involved adsorption on the metal surface and the concentration of oxygen vacancies in the support. Finally the Cu50Ni50/SDC catalyst was found to be thermally stable for 48 hours at 600/700°C.


2010 ◽  
Vol 1264 ◽  
Author(s):  
Jean-Marc Costantini ◽  
François Beuneu

AbstractWe present a study of point-defect creation in yttria-stabilized zirconia (ZrO2: Y) or YSZ exposed to various heavy ions (from C to U) covering an energy range from 100 MeV to several GeVs. It is concluded that F+-type centers (involving singly-ionized oxygen vacancies) are produced by elastic-collision processes. The ion-induced out-of-plane expansion is found to be small (< 0.2%) and to increase linearly as a function of the average F+-type center concentration with a large slope compatible with small oxygen vacancy clusters. The large defect volume and <100> axial symmetry of the F+-type centers hint that these color centers might actually be divacancies (i.e. F2+ centers).


Author(s):  
AB Silva ◽  
Jorge-E Rueda-P ◽  
Q Gomes K

Ceramics based bismuth vanadate are conductors of oxygen ions and they are used as solid electrolytes in pressure sensors and fuel cells. These materials operate at temperatures above 700 °C. At high temperatures, the bismuth-vanadium oxide (Bi4V2O11) has a g-phase with a large number of oxygen vacancies that favors the ionic conductivity. The g-phase of the Bi4V2O11 was stabilized at room temperature by partial substitution of vanadium (V5+) ions by cuprum (Cu2+) and zinc (Zn2+) ions to provide high ionic conductivity values between 100 and 400oC. Thus, polycrystalline samples of Bi4V1.8Cu0.1Zn0.1O10.7 were obtained after 4h sintering at 800 °C. Investigations were made about densification process and ionic conductivity related to the effect of addition of the yttria-stabilized zirconia (Zr0.88Y0.12O1.94).


2021 ◽  
Author(s):  
Hwanseok Lee ◽  
Kanghee Jo ◽  
Min-sung Park ◽  
Taewoo Kim ◽  
Heesoo Lee

Abstract The degradation behavior of yttria-stabilized zirconia under thermal stress was investigated in terms of phase transformation, local atomic structure, and electrical conductivity. The average grain size of 8YSZ were increased from 20.83 µm to 25.81 µm with increasing aging temperature. All 8YSZ samples degraded at different temperatures had a predominantly cubic structure. The (400) peak of 8YSZ deteriorated at 1300 and 1400°C shifted to high angle, and the peak of tetragonal was not indexed. For 8YSZ degraded at 1500°C, the (400) peak shifted to a lower angle, and the peak of tetragonal was identified. In the local atomic structure of the aged 8YSZ with extended X-ray absorption fine structure, the intensity of the Zr-O peak gradually increased, and the intensity of the Zr-Cation peak decreased as the aging temperature increased. The changes in the peaks indicate that the oxygen vacancies were reduced and Y3+ ions escaped from the lattice, leading to destabilization of 8YSZ. The activation energies of 8YSZ at 1300°C and 1400°C were derived to be 0.86 and 0.87 eV, respectively, and the activation energy of 8YSZ at 1500°C increased significantly to 0.92 eV. With the thermal deterioration of 8YSZ, the cation (Y3+) escaped from the lattice and the number of oxygen vacancies decrease, resulting in the formation of a tetragonal structure and high activation energy at 1500°C.


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