scholarly journals Achieving fast oxygen diffusion in perovskites by cation ordering

2005 ◽  
Vol 86 (9) ◽  
pp. 091910 ◽  
Author(s):  
A. A. Taskin ◽  
A. N. Lavrov ◽  
Yoichi Ando
Keyword(s):  
Oxygen Diffusion ◽  
Cation Ordering

Cation ordering and oxygen transport behaviour in Sr1−3x/2LaxTiO3perovskites

2017 ◽  
Vol 5 (11) ◽  
pp. 5321-5331 ◽  
Author(s):  
Paul C. M. Fossati ◽  
Robin W. Grimes
Keyword(s):  
Oxygen Transport ◽  
Oxygen Diffusion ◽  
Cation Ordering ◽  
Atomistic Modelling ◽  
Modelling Techniques ◽  
Transport Behaviour ◽  
Diffusion Mechanisms

Effects of cation ordering on oxygen diffusion mechanisms in (Sr,La)TiO3perovskites is investigated using atomistic modelling techniques.

Low-temperature annealing of YBa2Cu3O7-x

1992 ◽  
Vol 50 (1) ◽  
pp. 88-89
Author(s):  
R.L. Sabatini ◽  
Yimei Zhu ◽  
Masaki Suenaga ◽  
A.R. Moodenbaugh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Oxygen Diffusion ◽  
Diffusion Rate ◽  
Oxygen Depletion ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Microstructural Effects ◽  
Oxygen Diffusion Rate

Low temperature annealing (<400°C) of YBa2Cu3O7x in a ozone containing oxygen atmosphere is sometimes carried out to oxygenate oxygen deficient thin films. Also, this technique can be used to fully oxygenate thinned TEM specimens when oxygen depletion in thin regions is suspected. However, the effects on the microstructure nor the extent of oxygenation of specimens has not been documented for specimens exposed to an ozone atmosphere. A particular concern is the fact that the ozone gas is so reactive and the oxygen diffusion rate at these temperatures is so slow that it may damage the specimen by an over-reaction. Thus we report here the results of an investigation on the microstructural effects of exposing a thinned YBa2Cu3O7-x specimen in an ozone atmosphere using transmission electron microscopy and energy loss spectroscopy techniques.

The Effects of Nitrogen on Electrical and Structural Properties in TaSixNy/SiO2/p-Si MOS Capacitors

2002 ◽  
Vol 716 ◽  
Author(s):  
You-Seok Suh ◽  
Greg Heuss ◽  
Jae-Hoon Lee ◽  
Veena Misra
Keyword(s):  
Structural Properties ◽  
Electron Spectroscopy ◽  
Oxygen Diffusion ◽  
Gate Dielectric ◽  
Barrier Properties ◽  
Reaction Rates ◽  
Cross Sectional ◽  
Mos Capacitors ◽  
Transmission Electron ◽  
Thermal Stability Of

AbstractIn this work, we report the effects of nitrogen on electrical and structural properties in TaSixNy /SiO2/p-Si MOS capacitors. TaSixNy films with various compositions were deposited by reactive sputtering of TaSi2 or by co-sputtering of Ta and Si targets in argon and nitrogen ambient. TaSixNy films were characterized by Rutherford backscattering spectroscopy and Auger electron spectroscopy. It was found that the workfunction of TaSixNy (Si>Ta) with varying N contents ranges from 4.2 to 4.3 eV. Cross-sectional transmission electron microscopy shows no indication of interfacial reaction or crystallization in TaSixNy on SiO2, resulting in no significant increase of leakage current in the capacitor during annealing. It is believed that nitrogen retards reaction rates and improves the chemical-thermal stability of the gate-dielectric interface and oxygen diffusion barrier properties.

Dynamic changes in spatial microbial distribution in mixed-population biofilms: experimental results and model simulation

1995 ◽  
Vol 32 (8) ◽  
pp. 67-74 ◽  
Author(s):  
Satoshi Okabe ◽  
Kikuko Hirata ◽  
Yoshimasa Watanabe
Keyword(s):  
Oxygen Diffusion ◽  
Loading Rate ◽  
Model Simulation ◽  
Mixed Population ◽  
Experimental Results ◽  
Synthetic Wastewater ◽  
Diffusion Limitation ◽  
Dynamic Changes ◽  
Microbial Distribution ◽  
Rotating Biological Contactors

Dynamic changes in spatial microbial distribution in mixed-population biofilms were experimentally determined using a microslicer technique and simulated by a biofilm accumulation model (BAM). Experimental results were compared with the model simulation. The biofilms cultured in partially submerged rotating biological contactors (RBC) with synthetic wastewater were used as test materials. Experimental results showed that an increase of substrate loading rate (i.e., organic carbon and NH4-N) resulted in the microbial stratification in the biofilms. Heterotrophs defeated nitrifiers and dominated in the outer biofilm, whereas nitrifiers were diluted out in the outer biofilm and forced into the inner biofilm. At higher organic loading rates, a stronger stratified microbial spatial distribution was observed, which imposed a severe internal oxygen diffusion limitation on nitrifiers and resulted in the deterioration of nitrification efficiency. Model simulations described a general trend of the stratified biofilm structure. However, the actual stratification was stronger than the simulated results. For implication in the reactor design, when the specific carbon loading rate exceeds a certain limit, nitrification will be deteriorated or require a long start-up period due to the interspecies competition resulting in oxygen diffusion limitation. The extend of microbial stratification in the biofilm is especially important for determination of feasibility of nitrification in the presence of organic matters.

Use of a dynamic gassing-out method for activity and oxygen diffusion coefficient estimation in biofilms

1998 ◽  
Vol 37 (4-5) ◽  
pp. 171-175
Author(s):  
Artem Khlebnikov ◽  
Falilou Samb ◽  
Paul Péringer
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Uptake ◽  
Oxygen Diffusion ◽  
Fixed Bed ◽  
Biofilm Reactor ◽  
Strictly Aerobic ◽  
Comamonas Testosteroni ◽  
Respiration Activity ◽  
Oxygen Diffusion Coefficient ◽  
Biofilm Development

p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in multi-species biofilms was studied in a fixed bed biofilm reactor. The polypropylene static mixer elements (Sulzer Chemtech Ltd., Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. A strong relation between oxygen uptake and reactor degradation efficiency was observed, because p-toluenesulphonate degradation is a strictly aerobic process. This technique also allowed us to estimate the thickness of the active layer in the studied system. The mean active thickness was in order of 200 μm, which is close to maximum oxygen penetration depth in biofilms. A transient mathematical model was established to evaluate oxygen diffusitivity in non-steady-state biofilms. Based on the DO concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The oxygen diffusion coefficient obtained (2 10−10-1.2 10−9 m2 s−1) is in good agreement with published values. The DO diffusion coefficient varied with biofilm development. This may be, most likely, due to the biofilm density changes during the experiments. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design.

Structural, electrical characterization and oxygen-diffusion paths in LaSrGa1-xMgxO4-δ (x=0.0-0.2) layered perovskites: an impedance spectroscopy and neutron diffraction study

2021 ◽  
Author(s):  
Carlos Marino ◽  
Juan Basbus ◽  
Ana L. Larralde ◽  
Jose Antonio Alonso ◽  
Maria Teresa Fernandez-Diaz ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Neutron Diffraction ◽  
Structural Characterization ◽  
Oxygen Diffusion ◽  
Electrical Characterization ◽  
Neutron Diffraction Study ◽  
Oxygen Ions ◽  
Diffusion Paths ◽  
Layered Perovskites

This work presents the results of the structural characterization of LaSrGa1-xMgxO4-δ oxides with x=0.0-0.2 (LSGM'); these oxides with layered K2NiF4-type structure are potential electrolytes of oxygen ions with applications in...

Sign in / Sign up

Export Citation Format

Share Document