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.

Defects and Polytype Instabilities

2018 ◽  
Vol 924 ◽  
pp. 147-150
Author(s):  
Jörg Pezoldt ◽  
Andrei Alexandrovich Kalnin
Keyword(s):  
Long Range ◽  
Basal Plane ◽  
Partial Dislocation ◽  
Stacking Faults ◽  
Dislocation Loops ◽  
Elastic Fields ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Shockley Dislocation ◽  
Polytype Structure

A model based on the generation and recombination of defect was developed to describe the stability of stacking faults and basal plane dislocation loops in crystals with layered polytype structures. The stability of the defects configuration was analysed for stacking faults surrounded by Shockley and Frank partial dislocation as well as Shockley dislocation dipoles with long range elastic fields. This approach allows the qualitative prediction of defect subsystems in polytype structure in external fields.

Effects of Basal Plane Dislocation Density in 4H-SiC Substrate on Degradation of Body-Diode Forward Voltage

2016 ◽  
Vol 858 ◽  
pp. 384-388 ◽  
Author(s):  
Naoyuki Kawabata ◽  
Atsushi Tanaka ◽  
Masatoshi Tsujimura ◽  
Yoshinori Ueji ◽  
Kazuhiko Omote ◽  
...  
Keyword(s):  
Basal Plane ◽  
Field Effect Transistors ◽  
Forward Bias ◽  
Oxide Semiconductor ◽  
Strong Positive Correlation ◽  
Forward Voltage ◽  
Bias Stress ◽  
Before And After ◽  
Basal Plane Dislocation ◽  
The Difference

We investigated the effect of the basal plane dislocation (BPD) density in 4H-silicon carbide (SiC) substrates on the forward voltage (Vsd) degradation of body-diodes. Using reflection X-ray topography, the BPD density was automatically estimated from the substrates prior to fabrication of metal–oxide–semiconductor field-effect transistors (MOSFETs). A strong positive correlation was found between the Vsd shift, which was calculated from the difference before and after forward bias stress at 160 A/cm2 for ~500 hours, and the BPD density of the substrate. We show that it is possible to predict Vsd shifts from the BPD densities of SiC substrates prior to the fabrication of MOSFETs. In addition, we examined the origin of stacking faults (SFs) as a result of the application of forward bias stress. We presume that SFs are formed by BPDs converted to threading edge dislocations at the epi/sub interface, as well as by BPDs penetrating into the epitaxial layer.

Degradation of Majority Carrier Conductions and Blocking Capabilities in 4H-SiC High Voltage Devices due to Basal Plane Dislocations

2008 ◽  
Vol 1069 ◽  
Author(s):  
Sei-Hyung Ryu ◽  
Qingchun Zhang ◽  
Husna Fatima ◽  
Sarah Haney ◽  
Robert Stahlbush ◽  
...  
Keyword(s):  
High Voltage ◽  
Basal Plane ◽  
Voltage Drop ◽  
Schottky Diodes ◽  
Forward Bias ◽  
Stacking Faults ◽  
Majority Carrier ◽  
Before And After ◽  
Forward Voltage Drop ◽  
Basal Plane Dislocation

ABSTRACTThis paper presents the effect of recombination-induced stacking faults on the drift based forward conduction and leakage currents of high voltage 4H-SiC power devices. To show the effects, 10 kV 4H-SiC MPS (Merged PiN Schottky) diodes have been fabricated on a standard wafer and a low BPD (Basal Plane Dislocation) wafer, and their IV characteristics were evaluated before and after a forward bias stress, which resulted in minority carrier recombination and conductivity modulation in the drift epilayer of the diodes. After the stressing, the diode fabricated on standard wafer showed a significant increase in forward voltage drop, as well as a marked increase in leakage current, which were due to induction of stacking faults. The diode on the low BPD wafer showed very little change after the stress because the induction of stacking faults was minimized. Similar results were also observed on a 10 kV 4H-SiC DMOSFET. The results suggest that recombination-induced stacking faults are detrimental to all device types, and injection of minority carriers in majority carrier devices should be avoided at all times.

Effect of oxygen content on flux pinning in Nd-Ba-Cu-O single crystals

2001 ◽  
Vol 11 (1) ◽  
pp. 3639-3642 ◽  
Author(s):  
Y. Feng ◽  
A.K. Pradhan ◽  
S. Shibata ◽  
T. Machi ◽  
N. Koshizuka
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Flux Pinning ◽  
Effect Of Oxygen

Basal plane dislocation-threading edge dislocation complex dislocations in 6H-SiC single crystals

2015 ◽  
Vol 5 (1) ◽  
pp. 63-67 ◽  
Author(s):  
Wei Sun ◽  
Youting Song ◽  
Chunjun Liu ◽  
Tonghua Peng ◽  
Wenjun Wang ◽  
...  
Keyword(s):  
Single Crystals ◽  
Edge Dislocation ◽  
Basal Plane ◽  
Basal Plane Dislocation

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

The Challenges in Dealing with Organized Crime and its Consequences in Modern Societies in Albania, Kosovo and Macedonia – the Balkan Peninsula

2015 ◽  
Vol 5 (1) ◽  
pp. 161
Author(s):  
Bashkim Selmani ◽  
Bekim Maksuti
Keyword(s):  
Organized Crime ◽  
Balkan Peninsula ◽  
Human Mind ◽  
Negative Consequences ◽  
The Public ◽  
Before And After ◽  
History Of ◽  
European Standards ◽  
Organized Crime Groups ◽  
Further Development

The profound changes within the Albanian society, including Albania, Kosovo and Macedonia, before and after they proclaimed independence (in exception of Albania), with the establishment of the parliamentary system resulted in mass spread social negative consequences such as crime, drugs, prostitution, child beggars on the street etc. As a result of these occurred circumstances emerged a substantial need for changes within the legal system in order to meet and achieve the European standards or behaviors and the need for adoption of many laws imported from abroad, but without actually reading the factual situation of the psycho-economic position of the citizens and the consequences of the peoples’ occupations without proper compensation, as a remedy for the victims of war or peace in these countries. The sad truth is that the perpetrators not only weren’t sanctioned, but these regions remained an untouched haven for further development of criminal activities, be it from the public state officials through property privatization or in the private field. The organized crime groups, almost in all cases, are perceived by the human mind as “Mafia” and it is a fact that this cannot be denied easily. The widely spread term “Mafia” is mostly known around the world to define criminal organizations.The Balkan Peninsula is highly involved in these illegal groups of organized crime whose practice of criminal activities is largely extended through the Balkan countries such as Kosovo, Albania, Macedonia, Serbia, Bosnia, Croatia, Montenegro, etc. Many factors contributed to these strategic countries to be part of these types of activities. In general, some of the countries have been affected more specifically, but in all of the abovementioned countries organized crime has affected all areas of life, leaving a black mark in the history of these states.

scholarly journals Investigation of Hydrothermally Stressed Silicone Rubber/Silica Micro and Nanocomposite for the Coating High Voltage Insulation Applications

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3567
Author(s):  
Faiza Faiza ◽  
Abraiz Khattak ◽  
Safi Ullah Butt ◽  
Kashif Imran ◽  
Abasin Ulasyar ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Structural Changes ◽  
Polymer Chains ◽  
Hydrothermal Conditions ◽  
Silica Filler ◽  
Before And After ◽  
Aging Conditions ◽  
The Stability ◽  
Micro Silica ◽  
Applied Stresses

Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

scholarly journals Synthesis and Photobehavior of a NewDehydrobenzoannulene-Based HOF with Fluorine Atoms: From Solution to Single Crystals Observation

2021 ◽  
Vol 22 (9) ◽  
pp. 4803
Author(s):  
Eduardo Gomez ◽  
Ichiro Hisaki ◽  
Abderrazzak Douhal
Keyword(s):  
Charge Transfer ◽  
Single Crystals ◽  
Parent Compound ◽  
Time Resolved ◽  
Strong Basis ◽  
Triplet Structure ◽  
Carboxylic Groups ◽  
Potential Applications ◽  
A Charge ◽  
Further Development

Hydrogen-bonded organic frameworks (HOFs) are the focus of intense scientific research due their potential applications in science and technology. Here, we report on the synthesis, characterization, and photobehavior of a new HOF (T12F-1(124TCB)) based on a dehydrobenzoannulene derivative containing fluorine atoms (T12F-COOH). This HOF exhibits a 2D porous sheet, which is hexagonally networked via H-bonds between the carboxylic groups, and has an interlayers distance (4.3 Å) that is longer than that of a typical π–π interaction. The presence of the fluorine atoms in the DBA molecular units largely increases the emission quantum yield in DMF (0.33, T12F-COOH) when compared to the parent compound (0.02, T12-COOH). The time-resolved dynamics of T12F-COOH in DMF is governed by the emission from a locally excited state (S1, ~ 0.4 ns), a charge-transfer state (S1(CT), ~ 2 ns), and a room temperature emissive triplet state (T1, ~ 20 ns), in addition to a non-emissive triplet structure with a charge-transfer character (T1(CT), τ = 0.75 µs). We also report on the results using T12F-ester. Interestingly, FLIM experiments on single crystals unravel that the emission lifetimes of the crystalline HOF are almost twice those of the amorphous ones or the solid T12F-ester sample. This shows the relevance of the H-bonds in the photodynamics of the HOF and provides a strong basis for further development and study of HOFs based on DBAs for potential applications in photonics.

A New Hafnium-Beryllium System Prioduced by Ion Implantation and Annealing Techniques

1983 ◽  
Vol 27 ◽  
Author(s):  
J.C. Soares ◽  
A.A. Melo ◽  
M.F. DA Silva ◽  
E.J. Alves ◽  
K. Freitag ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Single Crystals ◽  
Room Temperature ◽  
Low Dose ◽  
Correlation Method ◽  
High Dose ◽  
Tetrahedral Sites ◽  
Time Differential ◽  
Before And After ◽  
Beryllium Foil

ABSTRACTLow and high dose hafnium imolanted beryllium samoles have been prepared at room temperature by ion implantation of beryllium commercial foils and single crystals. These samples have been studied before and after annealing with the time differential perturbed angular correlation method (TDPAC) and with Rutherford backscattering and channeling techniques. A new metastable system has been discovered in TDPAC-measurements in a low dose hafnium implanted beryllium foil annealed at 500°C. Channeling measurements show that the hafnium atoms after annealing, are in the regular tetrahedral sites but dislocated from the previous position occupied after implantation. The formation of this system is connected with the redistribution of oxygen in a thin layer under the surface. This effect does not take place precisely at the same temperature in foils and in single crystals.

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