On the Twin Formation in Orthorhombic Y1Ba2Cu3O7-Y

1987 ◽  
Vol 99 ◽  
Author(s):  
D. Rios-Jara ◽  
C. Varea ◽  
A. Robledo ◽  
A. Huanosta ◽  
J. M. Dominguez ◽  
...  
Keyword(s):  
Oxygen Content ◽  
Orthorhombic Phase ◽  
Electron Energy Loss Spectrometry ◽  
Relative Value ◽  
Kinetics Of Formation ◽  
Twin Formation ◽  
The Stability ◽  
Electron Energy Loss ◽  
Kinetics Of ◽  
Scanning Electron

ABSTRACTTransmission and scanning electron microscopy were used to study some features of twins in the orthorhombic phase of Y1Ba2Cu3O7-Y compounds. A model that explains the formation and proliferation of thene defectr, is proposed. Some conclusions about the kinetics of formation of these defects are stated, which agree with observed changes in twin densities produced by different cooling rates. Electron energy loss spectrometry (EELS) was ucod to measure relative changes in oxygen, which give some information about the relative value and the stability of oxygen content in twinned regions. A Braggs-Williams model of the order-disorder transition, for oxygen occupancies in the Cu-O2 planes, predicts an enrichment of vacancies at the boundaries in these oxygen deficient perovskites. This could explain the observed deficiency in oxygen content with respect to the perfect Y1Ba2Cu3O7 stoichio-metry.

Kinetics of formation and the stability of paramagnetic particles which appear during adsorption of anthracene on aluminosilicates

1973 ◽  
Vol 6 (5) ◽  
pp. 541-544
Author(s):  
M. N. Zhavoronkov ◽  
E. N. Rosolovskaya ◽  
K. V. Topchieva ◽  
V. B. Golubev
Keyword(s):  
Kinetics Of Formation ◽  
The Stability ◽  
Kinetics Of

Synthesis and Structure of a Novel Substituted Benzothiazolyl-N-phenyl-2-pyridinecarbothioamide; Kinetics of Formation and Electrochemistry of Two of its Palladium Pincer Complexes

2015 ◽  
Vol 68 (5) ◽  
pp. 731 ◽  
Author(s):  
Mark A.W. Lawrence ◽  
Yvette A. Jackson ◽  
Willem H. Mulder ◽  
Per Martin Björemark ◽  
Mikael Håkansson
Keyword(s):  
Complex Formation ◽  
Stability Constant ◽  
Palladium Complex ◽  
Coordination Complexes ◽  
Pincer Complexes ◽  
Kinetics Of Formation ◽  
Acetonitrile Solutions ◽  
The Stability ◽  
Electron Transfers ◽  
Kinetics Of

The synthesis and crystal structures of bis-N-(2,5-dimethoxyphenyl)pyridine-2,6-dicarbothioamide (dicarbothioamide I) and 6-(4,7-dimethoxy-2-benzothiazolyl)-N-(2,5-dimethoxyphenyl)-2-pyridinecarbothioamide (L1) as well as the syntheses of the palladium(ii) chloride and acetate pincer complexes are reported. The stability constant for the palladium complex formation at 25°C was found to be (2.04 ± 0.26) × 104 dm3 mol–1 and (2.30 ± 0.19) × 104 dm3 mol–1 with ΔfH = 8 ± 1 kJ mol–1, ΔfSθ = 108 ± 10 J K–1 mol–1, and ΔfH = 17 ± 4 kJ mol–1 and ΔfSθ = 140 ± 20 J K–1 mol–1 for the PdClL1 and Pd(OAc)L1, respectively. The kinetics of formation of the palladium(ii) complexes were investigated and the mechanism is proposed to be associative in nature (ΔH1‡ = 34 ± 2 kJ mol–1 and ΔS1‡ = –113 ± 8 J K–1 mol–1, and ΔH1‡ = 37 ± 3 kJ mol–1 and ΔS1‡ = –100 ± 8 J K–1 mol–1 for the PdClL1 and Pd(OAc)L1 species, respectively). The electrochemical measurements of the acetonitrile solutions revealed irreversible electron transfers consistent with the electrochemical decomposition of the ligand and its coordination complexes.

On the Effects of Hydrothermal Treatments on the Corrosion Resistance of the TSA Anodized AA7475-T761 Alloy

2016 ◽  
Vol 710 ◽  
pp. 169-174 ◽  
Author(s):  
Thallis Leal Almeida ◽  
Fernanda Martins Queiroz ◽  
Maysa Terada ◽  
Isolda Costa ◽  
Vera Rosa Capelossi
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Hydrothermal Treatment ◽  
Treatment Time ◽  
Electrochemical Impedance ◽  
Anodic Layer ◽  
The Stability ◽  
Kinetics Of ◽  
Hydrothermal Treatment Time ◽  
Scanning Electron

The effect of hydrothermal treatment time on sealing and corrosion resistance of the AA7475-T761 anodized aluminium alloy has been investigated in this study. The hydrothermal treatments tested are environmental compatible without chromium ions involved. Anodizing was carried out by a tartaric-sulphuric anodizing (TSA) process and this was followed by hydrothermal treatments for partial sealing, in various solutions. The effect of propyleneglycol (PRG) and/or cerium ions in the hydrothermal treatment solution was evaluated. Four treatment times were tested, specifically, 2.5, 5.0, 7.5 and 10 min. The corrosion resistance of the anodized and treated samples was evaluated by Electrochemical Impedance Spectroscopy (EIS) and the anodic layers formed were characterized by Scanning Electron Microscopy (SEM). The EIS results showed that the hydrothermal treatments in solutions with cerium ions resulted in similar impedances for periods of treatment from 5 to 10 min whereas in the solutions with PRG the impedance increased with time of treatment from 2.5 to 10 min showing a slower kinetics of anodic layer sealing. However, the fastest kinetics of sealing were associated to the treatments that combined two steps, one in PRG and other in cerium containing solutions with similar impedances obtained from 2.5 to 10 min of treatment. Surface evaluation by SEM showed that the porosities in the anodic layer were not sealed for the periods of hydrothermal treatments corresponding to 2.5 min. The presence of cerium in hydrothermal treatment had a beneficial effect on the stability of the anodic layer formed and provided a healing effect on the corroding sites.

The Effect of Ions on the Kinetics of Formation and the Stability of the Collagen-Fold*

Biochemistry ◽  
1962 ◽  
Vol 1 (4) ◽  
pp. 664-674 ◽  
Author(s):  
Peter H. von Hippel ◽  
Kwok-Ying Wong
Keyword(s):  
Kinetics Of Formation ◽  
The Stability ◽  
Kinetics Of

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

Corrections for surface films in microanalysis by EDS and EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1230-1231
Author(s):  
J. Bentley ◽  
E. A. Kenik
Keyword(s):  
Hydrocarbon Contamination ◽  
Specimen Preparation ◽  
Surface Films ◽  
Ion Milling ◽  
Preferential Sputtering ◽  
Electron Energy Loss Spectrometry ◽  
Composition Determination ◽  
Analytical Electron ◽  
First Order Correction ◽  
Electron Energy Loss

Common artifacts on analytical electron microscope (AEM) specimens prepared from bulk materials are surface films with altered structure and composition that result from electropolishing, oxidation, hydrocarbon contamination, or ion milling (preferential sputtering or deposition of sputtered specimen or support material). Of course, the best solution for surface films is to avoid them by improved specimen preparation and handling procedures or to remove them by low energy ion sputter cleaning, a capability that already exists on some specialized AEMs and one that is likely to become increasingly common. However, the problem remains and it is surprising that surface films have not received more attention with respect to composition determination by energy dispersive X-ray spectrometry (EDS) and electron energy loss spectrometry (EELS).For EDS, an effective first-order correction to remove the contribution of surface films on wedge shaped specimens is to subtract from the spectrum of interest a spectrum obtained under identical conditions (probe current, diffracting conditions, acquisition live time) from a thinner region of the specimen.

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

2003 ◽  
Vol 764 ◽  
Author(s):  
D.N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. Motayed ◽  
S.N. Mohammad
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Resolution Electron ◽  
Order Of Magnitude ◽  
Contact Surfaces ◽  
Electron Energy Loss ◽  
Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

A new species of Cribraria (Myxomycetes) from Australia

2018 ◽  
Vol 52 (2) ◽  
pp. 379-385 ◽  
Author(s):  
S. L. Stephenson ◽  
Yu. K. Novozhilov ◽  
P. Wellman
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Species ◽  
Lemon Yellow ◽  
Moist Chamber ◽  
Light Yellow ◽  
Dark Violet ◽  
The Stability ◽  
A New Species ◽  
Scanning Electron

A new species of Cribraria, described herein as C. bicolor, appeared in moist chamber cultures on samples of the bark of Eucalyptus sp. collected at two localities in Australia. The morphology of representative specimens was examined by light and scanning electron microscopy, and micrographs of relevant morphological details of sporocarps and spores are provided. The species has a number of distinct and unique morphological features, including a glossy bright-violet globose sporotheca and a two-colored long stalk which is bright-red over the lower one-third and light yellow or lemon-yellow over the upper two-thirds. The combination of these characteristics as well as a shallow calyculus which is dark-violet when viewed under a dissecting microscope and bright red in transmitted light when mounted in lactophenol makes C. bicolor a well-defined morphospecies when compared to all other species of Cribraria. The stability of the taxonomic characters of the species was confirmed by an examination of a number of specimens.

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