Effective Concentration of Mobile Oxygen-Vacancies in Heavily Doped Cubic Zirconia: Results from Combined Electrochemical Impedance and NMR Spectroscopies

2012 ◽  
Vol 24 (18) ◽  
pp. 3604-3609 ◽  
Author(s):  
Chien-Ting Chen ◽  
Sabyasachi Sen ◽  
Sangtae Kim
Keyword(s):  
Oxygen Vacancies ◽  
Electrochemical Impedance ◽  
Effective Concentration ◽  
Cubic Zirconia ◽  
Heavily Doped ◽  
Mobile Oxygen

scholarly journals Transport Properties and High Temperature Raman Features of Heavily Gd-Doped Ceria

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4148 ◽  
Author(s):  
Cristina Artini ◽  
Sabrina Presto ◽  
Sara Massardo ◽  
Marcella Pani ◽  
Maria Maddalena Carnasciali ◽  
...  
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Oxygen Vacancies ◽  
Arrhenius Plot ◽  
Solid Oxide ◽  
Raman Shift ◽  
Threshold Temperature ◽  
Doped Ceria ◽  
Lower Activation ◽  
Slope Change ◽  
Heavily Doped

Transport and structural properties of heavily doped ceria can reveal subtle details of the interplay between conductivity and defects aggregation in this material, widely studied as solid electrolyte in solid oxide fuel cells. The ionic conductivity of heavily Gd-doped ceria samples (Ce1−xGdxO2−x/2 with x ranging between 0.31 and 0.49) was investigated by impedance spectroscopy in the 600–1000 K temperature range. A slope change was found in the Arrhenius plot at ~723 K for samples with x = 0.31 and 0.34, namely close to the compositional boundary of the CeO2-based solid solution. The described discontinuity, giving rise to two different activation energies, points at the existence of a threshold temperature, below which oxygen vacancies are blocked, and above which they become free to move through the lattice. This conclusion is well supported by Raman spectroscopy, due to the discontinuity revealed in the Raman shift trend versus temperature of the signal related to defects aggregates which hinder the vacancies movement. This evidence, observable in samples with x = 0.31 and 0.34 above ~750 K, accounts for a weakening of Gd–O bonds within blocking microdomains, which is compatible with the existence of a lower activation energy above the threshold temperature.

scholarly journals Oxygen Vacancy Enhanced Photoreduction Cr(VI) on Few-Layers BiOBr Nanosheets

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 558 ◽  
Author(s):  
Yin Peng ◽  
Pengfei Kan ◽  
Qian Zhang ◽  
Yinghua Zhou
Keyword(s):  
Oxygen Vacancies ◽  
Surface Defect ◽  
Photocatalytic Performance ◽  
Electrochemical Impedance ◽  
Light Irradiation ◽  
Solvothermal Reaction ◽  
Defect Engineering ◽  
High Concentration ◽  
Solar Light Irradiation ◽  
2D Nanomaterials

2D nanomaterials, with unique structural and electronic features, had been demonstrated as excellent photocatalysts, whose catalytic properties could be tunable with surface defect engineering. In this work, few-layer BiOBr nanosheets with oxygen vacancies (BiOBr-Ov) have been fabricated by a simple solvothermal reaction with the help of ethylene glycol. The obtained BiOBr-Ov exhibited the superior photocatalytic performance with a complete reduction of Cr(VI) (20 mg/L) within 12 min by visible light irradiation. Moreover, Cr(VI) with a high concentration (such as 30 mg/L) only requires 2 min to be photoreduced completely under solar light irradiation. The enhanced photocatalytic performance is contributed to the existence of oxygen vacancies. It has been proved by the results of electrochemical impedance and photocurrent that oxygen vacancies can effectively suppress recombination of photogenerated carriers.

Strain screening by mobile oxygen vacancies in SrTiO3

2010 ◽  
Vol 96 (25) ◽  
pp. 251901 ◽  
Author(s):  
Yongsam Kim ◽  
Ankit S. Disa ◽  
Timur E. Babakol ◽  
Joel D. Brock
Keyword(s):  
Oxygen Vacancies ◽  
Strain Screening ◽  
Mobile Oxygen

scholarly journals Oxygen Vacancies in Perovskite Oxide Piezoelectrics

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5596
Author(s):  
Marina Tyunina
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Chemical Reactions ◽  
Oxygen Vacancies ◽  
Perovskite Oxide ◽  
Semiconductor Physics ◽  
Physical Conditions ◽  
Ferroelectric Behavior ◽  
Piezoelectric Performance ◽  
Mobile Oxygen

The excellent electro-mechanical properties of perovskite oxide ferroelectrics make these materials major piezoelectrics. Oxygen vacancies are believed to easily form, migrate, and strongly affect ferroelectric behavior and, consequently, the piezoelectric performance of these materials and devices based thereon. Mobile oxygen vacancies were proposed to explain high-temperature chemical reactions half a century ago. Today the chemistry-enabled concept of mobile oxygen vacancies has been extrapolated to arbitrary physical conditions and numerous effects and is widely accepted. Here, this popular concept is questioned. The concept is shown to conflict with our modern physical understanding of ferroelectrics. Basic electronic processes known from mature semiconductor physics are demonstrated to explain the key observations that are groundlessly ascribed to mobile oxygen vacancies. The concept of mobile oxygen vacancies is concluded to be misleading.

scholarly journals Lattice distortions and oxygen vacancies produced in Au+-irradiated nanocrystalline cubic zirconia

2011 ◽  
Vol 65 (8) ◽  
pp. 675-678 ◽  
Author(s):  
Philip D. Edmondson ◽  
William J. Weber ◽  
Fereydoon Namavar ◽  
Yanwen Zhang
Keyword(s):  
Oxygen Vacancies ◽  
Cubic Zirconia ◽  
Lattice Distortions

A-site deficient perovskite: the parent for in situ exsolution of highly active, regenerable nano-particles as SOFC anodes

2015 ◽  
Vol 3 (20) ◽  
pp. 11048-11056 ◽  
Author(s):  
Yifei Sun ◽  
Jianhui Li ◽  
Yimin Zeng ◽  
Babak Shalchi Amirkhiz ◽  
Mengni Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Oxygen Vacancies ◽  
Electronic Conductivity ◽  
Nano Particles ◽  
Highly Active ◽  
A Site ◽  
Mobile Oxygen

Introduction of A-site deficiency on Ni-doped LaSrCrO3 anodes helps form highly mobile oxygen vacancies and remarkably enhances Ni nanoparticle reducibility, and significantly increases electronic conductivity and catalytic activity.

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