scholarly journals Activating Lattice Oxygen in Perovskite Oxide by B‐Site Cation Doping for Modulated Stability and Activity at Elevated Temperatures

2021 ◽  
pp. 2102713
Author(s):  
Huijun Chen ◽  
Chaesung Lim ◽  
Mengzhen Zhou ◽  
Zuyun He ◽  
Xiang Sun ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Lattice Oxygen ◽  
Perovskite Oxide ◽  
Cation Doping

scholarly journals The changes of Ba0.5Sr0.5Co0.8Fe0.2O3-δ perovskite oxide on heating in oxygen and carbon dioxide atmospheres

2014 ◽  
Vol 79 (9) ◽  
pp. 1141-1154 ◽  
Author(s):  
Sasa Zeljkovic ◽  
Toni Ivas ◽  
Sebastien Vaucher ◽  
Dijana Jelic ◽  
Ludwig Gauckler
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Elevated Temperatures ◽  
Oxygen Deficiency ◽  
Perovskite Oxide ◽  
X Ray ◽  
Equilibrium Reaction ◽  
Increasing Temperature

In the first part of this study, the oxygen deficiency, ?, in Ba0.5Sr0.5Co0.8Fe0.2O3 - ? (BSCF) was measured by means of thermogravimetry as a function of oxygen partial pressure, p(O2), in the range of 1.1?10?6 < p(O2)/% < 41.67 at elevated temperatures ranging 873 ? T/K ? 1073. It was shown that ? becomes more pronounced with increasing T and with decreasing p(O2). The isotherms ? vs. p(O2) were determined. The second part of this study relates to the reaction of CO2 with Ba0.5Sr0.5Co0.8Fe0.8O3-? perovskite oxide in the absence and presence of O2 at temperatures ranging from 673 to 973 K also by thermogravimetry. The reactivity of CO2 with BSCF increased with increasing temperature and increasing exposure to CO2. Reaction of CO2 with BSCF was described by a equilibrium reaction isotherms. The results of X-ray diffractometry evidenced that the exposure to CO2 leads to the formation of carbonates.

Oxygen Diffusivity of La0.6Sr0.4Co0.2Fe0.8O3-δ Perovskite Oxide

2012 ◽  
Vol 616-618 ◽  
pp. 633-637
Author(s):  
Yan Wei Liu ◽  
Zhe Lü
Keyword(s):  
Thermal Expansion ◽  
Diffusion Coefficient ◽  
Chemical Diffusion ◽  
Lattice Oxygen ◽  
Perovskite Oxide ◽  
Chemical Diffusion Coefficient ◽  
Conductivity Relaxation ◽  
Fixed Temperature ◽  
Expansion Curve ◽  
Maximum Conductivity

La0.6Sr0.4Co0.2Fe0.8O3-δ composite oxide was prepared and characterized. Dilatometer and four-probe DC were exploited to investigate the thermal expansion and electrical conductivity, respectively. The thermal expansion curve was linear, but it became steeper at the high temperature region, as a result of the loss of lattice oxygen and the formation of oxygen vacancies. The conductivity increased with temperature up to about 600oC, and then decreased due to the loss of lattice oxygen. The maximum conductivity was more than 300 S cm-1. The chemical diffusion coefficient in La0.6Sr0.4Co0.2Fe0.8O3-δ was estimated by analyzing the conductivity relaxation behavior. The relaxation process of the conductivity change for La0.6Sr0.4Co0.2Fe0.8O3-δ was traced as a function of time, at a fixed temperature. It was found that the chemical diffusion coefficients measured at temperatures 720-770oC vary from 710-8 to 110-7 cm2 S-1. The activation energy for oxygen diffusion in La0.6Sr0.4Co0.2Fe0.8O3-δ, derived from the chemical diffusion coefficient is 40.8±3.6 kJ mol-1.

The enhancement of rate and cycle performance of LiMn2O4 at elevated temperatures by the synergistic roles of porous structure and dual-cation doping

2018 ◽  
Vol 48 (10) ◽  
pp. 1083-1094 ◽  
Author(s):  
Yuanfu Deng ◽  
Shanxing Wang ◽  
Yubo Zhou ◽  
Yunxian Qian ◽  
Xusong Qin ◽  
...  
Keyword(s):  
Porous Structure ◽  
Elevated Temperatures ◽  
Cycle Performance ◽  
Cation Doping

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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