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Article
Dimensionality crossover regimes due to microcrystalline anisotropy in the resistivity of granular Y1Ba2Cu3O7−y in weak magnetic fields at low temperature
Precise measurements of the electrical resitivity of Y1Ba2Cu3O7−y have been taken in the temperature range between the “percolation transition” temperatureT R and the “superco...
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Article
High temperature crossover in paraconductivity of granular Y1Ba2Cu3O7-y
We have examined the deviation from linearity of the temperature dependence of the electrical resistivity of a YBaCuO ceramics. We have observed at high temprature a crossover behavior toward a logarithmic tem...
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Article
Theory of the thermoelectric power of model semimetals and semiconductors
We briefly discuss available theories as well as hypotheses behind numerical work for the thermoelectric power (TEP). In particular we emphasize shortcomings for comparing usual theoretical and numerical resul...
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Article
Superconductivity fluctuations in Bi(Pb) based granular ceramics superconductors: evidence for fractal behavior
We report precise measurements of the electrical resistivity in three different Bi(Pb) based granular ceramics superconductors. We show that a single critical exponent (5/6) describes the superconductivity flu...
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Article
Theory of thermoelectric power of model semimetals and semiconductors
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Article
Systems of reduced electron concentration and dimensionality
Semi-conductors, semi-metals and high critical temperature superconductors are systems with a reduced number of carriers and present effects which are sometimes related to a reduced dimensionality. We consider...
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Article
Simulated growth and microstructure of DyBa2Cu3O7−x with and without Dy2BaCuO5 addition
We present optical observations of magnetically melt-textured DyBa2Cu3O7−x with and without 20 wt. % excess of Dy2BaCuO5. From these observations, we propose some kinetic mechanism of the growth of 123 compounds....
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Article
Magnetotransport study of in situ magnetic field textured Dy1Ba2Cu3O7−δ superconductors
The electrical resistivity, thermoelectric power and the Nernst effect have been studied as a function of temperature and magnetic field for a typical superconductor DyBa2Cu3O7−δ magnetically textured in situ at ...
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Article
Magnetic alignment in 2212 Bi-based superconducting system: II. Bi2Sr2Ca1−xDyxCu2O8−yx = 0.2 glass recrystallized in 0.6 T magnetic field
Starting from a glassy precursor, Bi2Sr2Ca1−xDyxCu2O8−y (for x = 0.2) was recrystallized under a 0.6 T magnetic field. After splat quenching, the samples were heated and sintered at different temperatures T1, the...
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Article
Non-isovalent alkali metal “substitution” in YBa2Cu3O7−y granular ceramics
The aim of this paper is to study the influence of non-isovalent “do**” in YBa2Cu3O7−y in particular on its synthesis conditions and on the resistive properties both with and without a magnetic field. We conce...
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Article
Field dependence of the electrothermal conductivity of high-Tc superconductors
The field dependence of the electrothermal conductivity P=S/ρ of high-Tc superconductors is calculated using a kinetic Boltzmann-like theory for either an s-wave or a d-wave gap parameter symmetry. The charge car...
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Article
Two dimensional self-organized transitions for propagation in random media
A simple so-called dynamic epidemic model, for the evolution of an advancing interface through a two-dimensional medium containing mobile impurities is investigated. A short range repulsion between the front a...
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Article
Magnetic alignment in 2212 Bi-based superconducting system: Part I. Magnetic orientation of Bi2Sr2Ca1−x(RE)xCu2O8−y [(RE) = Gd, Dy, Ho, Er] powder dispersed in epoxy resin at room temperature
The magnetic anisotropy of rare-earth substituted 2212 materials (Bi2Sr2Ca0.8RE0.2Cu2Ox with RE = Gd, Dy, Ho, Er) is put into evidence. Superconducting powder dispersed in epoxy resin is oriented under an externa...
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Article
Polarized light microstructure analysis of melt-textured DyBa2Cu3O7−x ceramics
We report the microstructure of magnetically melt-textured Dy-123 samples, as observed by polarized light metallography. The phase dimensions, morphology, orientation, nature, and distribution are outlined. Gr...
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Article
Microstructure development in isothermally melt-textured 123–211 composite materials
Microstructures of isothermally melt-textured 123–211 composite materials have been examined during the solidification process from quenched specimens. The distribution of 211 particles, the superconducting 12...
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Article
Field percolation and high current density in 80/20 DyBa2Cu3O7 − x/Dy2BaCuO5 bulk magnetically textured composite ceramics
We measured the AC susceptibility of magnetically textured (123) 80%/211(20%) DyBaCuO composite in a special set-up in order to enhance the intergrain contribution. The synthesis process led to very clean “wea...
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Article
Non-isovalent metal substitution for bismuth, strontium, calcium, and copper in bi-based 2212 superconducting ceramics
The aim of this paper is to investigate the influence of non-isovalent alkali (Li, Na, K, and Cs) substitution in Bi2Sr2CaCu2O8, in particular on its synthesis conditions and on their resistive and thermopower el...
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Article
Phase Transitions, Patterns and Statistical Mechanics of Front Propagation in a Dynamic Random Impurity Model for Strip, Unusual Trees and Other Geometries
A dynamic random impurity model is studied lor describing the evolution of an advancing interface through a multiphase random medium containing mobile impurities. A short range repulsion between the front and ...
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Article
Influence of a non-uniform current density profile on quasiparticle excitations and thermally activated flux creep in YBa2Cu3O7−σ
The transport current density, flowing radially from the center of a superconducting disk to its perimeter, in a so-called Corbino geometry, results in a double action on the vortex motion when the applied mag...
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Article
Directional solidification by appropriate chemically active single crystal seed: An alternative way of generating large superconducting 123 single domain
A Dy2O3 single crystal has been used as a seed for the growth of isothermally melt-textured Dy-123 material. The nucleation-controlled step has been observed to be related to the heterogeneous nucleation of 211 p...
