scholarly journals Determination of the enthalpy of hydration of oxygen vacancies in Y-doped BaZrO3 and BaCeO3 by TG-DSC

2010 ◽  
Vol 181 (39-40) ◽  
pp. 1740-1745 ◽  
Author(s):  
Christian Kjølseth ◽  
Lin-Yung Wang ◽  
Reidar Haugsrud ◽  
Truls Norby
Keyword(s):  
Oxygen Vacancies ◽  
Enthalpy Of Hydration

Determination of Diffusion Coefficients of Oxygen Vacancies in La0.58Sr0.4Co0.2Fe0.8O3-δ Perovskite Type Oxides

2009 ◽  
Vol 289-292 ◽  
pp. 551-554 ◽  
Author(s):  
D. Schlehuber ◽  
Egbert Wessel ◽  
Lorenz Singheiser ◽  
T. Markus
Keyword(s):  
Power Plant ◽  
Oxygen Vacancies ◽  
Combustion Process ◽  
Efficient Technology ◽  
Different Temperatures ◽  
Diffusion Coefficient Of Oxygen ◽  
Perovskite Type ◽  
Permeation Properties ◽  
High Chemical Stability

One possibility to run a zero CO2-emission power plant is the oxyfuel combustion process. An efficient technology to separate oxygen from air are processes with oxygen transport membranes. It is important that these membranes have a high permeability additional to high chemical stability under power plant conditions. La0.58Sr0.4Co0.2Fe0.8O3- (LSCF) is a mixed ionic electronic conducting material (MIEC) which is considered to have good permeation properties and a high stability. In this work LSCF based membranes are investigated. Data from a TGA (Thermo-Gravimetric Analyser) have been used to determine the diffusion coefficient of oxygen vacancies in LSCF perovskite type oxides for different temperatures.

Effect of Sr Doping on Piezoelectric Properties of Pb(Mn1/3Nb2/3)O3-Pb(Zr,Ti)O3 Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 201-204
Author(s):  
Bao Shan Li ◽  
Guo Rong Li ◽  
Zhi Gang Zhu ◽  
Wang Zhong Zhang ◽  
Qing Rui Yin ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Oxygen Vacancies ◽  
Piezoelectric Properties ◽  
Sintering Temperature ◽  
Solid Phase ◽  
Coupling Factor ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Pzt Ceramics

This paper aims at the determination of the effects of strontium addition on the microstructural evolution and the piezoelectric properties for Pb(Mn1/3Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) ceramics. The Sr content was chosen in the range of 2-8 mol%. These materials were prepared by the solid phase reaction of the oxides. It was found, from the experimental results, the tetragonality of the PMnN-PZT lattice and the Curie temperature decreased with Sr content; in the meantime, dielectric constant increased greatly. Dielectric constant (er) and planar coupling factor (Kp) was proven to be dependent on sintering temperature. P-E curves of PMnN-PZT system exhibited some “pinched” shape instead of the normal square-like P-E loops, illustrating presence of the oxygen vacancies by reason of the preferable substitution of the B-sites ion.

Electrochemical sensor based on the Mn3O4/CeO2 nanocomposite with abundant oxygen vacancies for highly sensitive detection of hydrogen peroxide released from living cells

2021 ◽  
Vol 13 (14) ◽  
pp. 1672-1680
Author(s):  
Yalin Wu ◽  
Liping Lu ◽  
Zhihui Yu ◽  
Xiayan Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Electrochemical Sensor ◽  
Oxygen Vacancies ◽  
Living Cells ◽  
Sensitive Detection ◽  
Reliable Determination ◽  
Highly Sensitive ◽  
Highly Sensitive Detection

A novel electrochemical sensor based on the Mn3O4/CeO2 for reliable determination of extracellular H2O2 released from living cells was developed.

scholarly journals Эволюция проводимости и катодолюминесценции пленок оксида гафния при изменении концентрации вакансий кислорода

2018 ◽  
Vol 60 (10) ◽  
pp. 2006
Author(s):  
Д.Р. Исламов ◽  
В.А. Гриценко ◽  
В.Н. Кручинин ◽  
Е.В. Иванова ◽  
М.В. Заморянская ◽  
...  
Keyword(s):  
Refractive Index ◽  
Hafnium Oxide ◽  
Oxygen Vacancies ◽  
Trap Density ◽  
Blue Band ◽  
In Situ Method ◽  
Assisted Tunneling ◽  
Strong Scattering

AbstractThe dependence of the conductivity of the films of hafnium oxide HfO_2 synthesized in different modes is studied. Depending on the modes of synthesis, the conductivity of HfO_2 at a fixed electric field of 1.0 MV/cm changes by four orders of magnitude. It is found that the conductivity of HfO_2 is limited by the model of phonon-assisted tunneling between the traps. The thermal and optical energies of the traps W _t = 1.25 eV and W _opt = 2.5 eV, respectively, in HfO_2 are determined. It is found that the exponentially strong scattering of the conductivity of HfO_2 is due to the change in the trap density in a range of 4 × 10^19–2.5 × 10^22 cm^–3. In the cathodoluminescence spectra of HfO_2, a blue band with the energy of 2.7 eV is observed which is due to the oxygen vacancies. A correlation between the trap density and intensity of cathodoluminescence, as well as between the trap density and refractive index, is found. A nondestructive in situ method for the determination of the trap density of hafnium oxide with the use of the measurement of the refractive index is proposed. The optimum values of the concentrations of oxygen vacancies for emitting devices on the basis of the films of HfO_2 are found.

scholarly journals Femtosecond visualization of oxygen vacancies in metal oxides

2020 ◽  
Vol 6 (10) ◽  
pp. eaax9427 ◽  
Author(s):  
Xinping Zhang ◽  
Fawei Tang ◽  
Meng Wang ◽  
Wangbin Zhan ◽  
Huaxin Hu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Oxygen Vacancy ◽  
Metal Oxides ◽  
Oxygen Vacancies ◽  
Time Resolved ◽  
Tungsten Oxides ◽  
Structure Of Metal ◽  
Evolution Dynamics ◽  
Spatial Locations

Oxygen vacancies often determine the electronic structure of metal oxides, but existing techniques cannot distinguish the oxygen-vacancy sites in the crystal structure. We report here that time-resolved optical spectroscopy can solve this challenge and determine the spatial locations of oxygen vacancies. Using tungsten oxides as examples, we identified the true oxygen-vacancy sites in WO2.9 and WO2.72, typical derivatives of WO3 and determined their fingerprint optoelectronic features. We find that a metastable band with a three-stage evolution dynamics of the excited states is present in WO2.9 but is absent in WO2.72. By comparison with model bandstructure calculations, this enables determination of the most closely neighbored oxygen-vacancy pairs in the crystal structure of WO2.72, for which two oxygen vacancies are ortho-positioned to a single W atom as a sole configuration among all O─W bonds. These findings verify the existence of preference rules of oxygen vacancies in metal oxides.

scholarly journals Strain profiles in thin films: influence of a coherently diffracting substrate and thickness fluctuations

2008 ◽  
Vol 42 (1) ◽  
pp. 85-92 ◽  
Author(s):  
A. Boulle ◽  
F. Conchon ◽  
R. Guinebretière
Keyword(s):  
Oxygen Vacancies ◽  
Vertical Displacement ◽  
Epitaxial Films ◽  
X Ray Diffraction ◽  
Strain Profile ◽  
X Ray ◽  
Fitting Procedure ◽  
Displacement Profile ◽  
Model Independent

A simple least-squares fitting-based method is described for the determination of strain profiles in epitaxial films using high-resolution X-ray diffraction. The method is model-independent,i.e.it does not require any `guess' model for the shape of the strain profile. The shape of the vertical displacement profile is modelled using the versatile cubicB-spline functions, which puts smoothness and curvature constraints on the fitting procedure. The effect of a coherently diffracting substrate is taken into account as well as the effects of film thickness fluctuations. The model is applied to the determination of strain profiles in SmNiO3films epitaxically grown on SrTiO3(001) substrates. The shape of the retrieved strain profile is discussed in terms of oxygen vacancies.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

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