On The Optimized Mixing of Order and Disorder in High-Tc Ceramic Superconductors

1990 ◽  
Vol 195 ◽  
Author(s):  
E. Mezzelli
Keyword(s):  
Cayley Tree ◽  
The State ◽  
Localized States ◽  
Self Similarity ◽  
High Tc ◽  
Energy Eigenvalues ◽  
Ceramic Superconductors ◽  
Order And Disorder ◽  
Coherent Coupling ◽  
State Tree

ABSTRACTCoherent excitations of localized states, represented by a selfsimilar Cayley tree, produce a gap in the density of states, which is deeper as the number of generations increases.The model can suitably describe systems in which an optimized concentration of “defects” allows self similarity of the state-tree and coherent coupling between clusters of localized states.A renormalization of the state-tree leads to a hierarchy of the energy eigenvalues.

scholarly journals Supramolecular Fractal Growth of Self-Assembled Fibrillar Networks

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 46
Author(s):  
Pedram Nasr ◽  
Hannah Leung ◽  
France-Isabelle Auzanneau ◽  
Michael A. Rogers
Keyword(s):  
Fractal Dimension ◽  
Crystallization Temperature ◽  
Cayley Tree ◽  
Fractal Dimensions ◽  
Self Similarity ◽  
Avrami Model ◽  
Cluster Aggregation ◽  
Box Counting ◽  
Self Assembled ◽  
Limited Diffusion

Complex morphologies, as is the case in self-assembled fibrillar networks (SAFiNs) of 1,3:2,4-Dibenzylidene sorbitol (DBS), are often characterized by their Fractal dimension and not Euclidean. Self-similarity presents for DBS-polyethylene glycol (PEG) SAFiNs in the Cayley Tree branching pattern, similar box-counting fractal dimensions across length scales, and fractals derived from the Avrami model. Irrespective of the crystallization temperature, fractal values corresponded to limited diffusion aggregation and not ballistic particle–cluster aggregation. Additionally, the fractal dimension of the SAFiN was affected more by changes in solvent viscosity (e.g., PEG200 compared to PEG600) than crystallization temperature. Most surprising was the evidence of Cayley branching not only for the radial fibers within the spherulitic but also on the fiber surfaces.

The Nature of Flux Pinning in High TC Ceramic Superconductors / Die Wirkungsweise der Flußschlauch-Haftung in Keramik-Hochtemperatur-Supraleitern

1988 ◽  
Vol 79 (5) ◽  
pp. 271-277
Author(s):  
Chalakara V. Narasimha Rao ◽  
Shyam K. Agarwal ◽  
Betanabhatla Jayaram ◽  
Sylvester Takacs ◽  
Anant V. Narlikar
Keyword(s):  
Flux Pinning ◽  
High Tc ◽  
Ceramic Superconductors

A STRUCTURAL CHEMICAL MODEL FOR HIGH Tc CERAMIC SUPERCONDUCTORS

1987 ◽  
Vol 01 (07n08) ◽  
pp. 275-288 ◽  
Author(s):  
S.R. OVSHINSKY ◽  
S.J. HUDGENS ◽  
R.L. LINTVEDT ◽  
D.B. RORABACHER
Keyword(s):  
Electronic Properties ◽  
Oxygen Vacancies ◽  
Oxygen Removal ◽  
Bose Condensation ◽  
Oxidation States ◽  
Chemical Model ◽  
Electrically Conductive ◽  
High Tc ◽  
Ceramic Superconductors ◽  
Mixed Oxidation

A structual chemical model for high Tc ceramic superconductors is proposed in which carriers pairs, coupled through a superexchange process, undergo Bose condensation. In the Y-Ba-Cu-O system, Cu atoms on “chain” sites and “sheet” sites are initially assigned formal oxidation states of +3 and +2, respectively, and “sheet”/“chain” interactions are then introduced to bring about the electrically conductive mixed oxidation state. This model explains the presence of labile oxygen in the “chain” structures, describes the structure of deoxygenated phases exhibiting ordered oxygen vacancies in the “chains”, and allows interpretation of the effects of oxygen removal on magnetic and electronic properties of the material.

High-Tc Ceramic Superconductors Through Oxidation of Mechanically Alloyed Y-Ba-Cu and Bi-Sr-Ca-Cu Powders

1989 ◽  
pp. 281-286
Author(s):  
Shin-ichi Murasaki ◽  
Satoru Taniguchi ◽  
Uichiro Mizutani ◽  
Motohiro Suganuma ◽  
Yuh Yamada
Keyword(s):  
Mechanically Alloyed ◽  
High Tc ◽  
Ceramic Superconductors

Internal friction in high Tc iron doped 1-2-3 yttrium ceramic superconductors

1990 ◽  
Vol 74 (7) ◽  
pp. 595-598 ◽  
Author(s):  
B. Kusz ◽  
R. Barczynski ◽  
M. Gazda ◽  
L. Murawski ◽  
O. Gzowski ◽  
...  
Keyword(s):  
Internal Friction ◽  
High Tc ◽  
Ceramic Superconductors ◽  
Iron Doped

Point contact measurements on high Tc ceramic superconductors

1988 ◽  
Vol 37 (1) ◽  
pp. 138-140 ◽  
Author(s):  
Niels Hessel Andersen ◽  
Ib Johannsen ◽  
Mogens T Levinsen
Keyword(s):  
Point Contact ◽  
High Tc ◽  
Ceramic Superconductors ◽  
Contact Measurements
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