scholarly journals Thermal conductivity of materials used for preparation of the hybrid layered conductors based on high temperature superconductors

2012 ◽  
Author(s):  
N. Bagrets ◽  
M. Schwarz ◽  
C. Barth ◽  
K.-P. Weiss
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
High Temperature Superconductors ◽  
Materials Used

THERMAL CONDUCTIVITY OF HIGH TEMPERATURE SUPERCONDUCTORS

1991 ◽  
Vol 05 (12) ◽  
pp. 2003-2035 ◽  
Author(s):  
MANUEL D. NUÑEZ REGUEIRO ◽  
DARÍO CASTELLO
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Transition Temperature ◽  
Phonon Scattering ◽  
High Temperature Superconductors ◽  
Low Energy ◽  
Disordered Materials ◽  
Superconducting Transition ◽  
Universal Pattern ◽  
Heat Carriers

We review and analyze the data on the thermal conductivity of both ceramic and single crystal samples of high temperature superconductors. A universal pattern can be extracted and interpreted in the following way: phonons are the main heat carriers in these materials, and in the high temperature range the thermal conductivity κ is almost constant due to phonon scattering against disorder; below the superconducting transition temperature κ increases as phonon scattering against carriers condensing into the superconducting state decreases and at still lower temperatures there is a region in which a T2 law is obeyed that most probably is due to resonant phonon scattering against low energy excitations, i.e. tunneling systems similar to those found in disordered materials. The origin of the relevant disorder is discussed.

THEORY OF THERMAL CONDUCTIVITY OF HIGH TEMPERATURE SUPERCONDUCTORS: A NEW APPROACH

2011 ◽  
Vol 25 (09) ◽  
pp. 663-678 ◽  
Author(s):  
VINOD ASHOKAN ◽  
B. D. INDU
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Phonon Scattering ◽  
High Temperature Superconductors ◽  
Relaxation Times ◽  
Impurity Scattering ◽  
Resonance Scattering ◽  
Perturbative Approach ◽  
Conductivity Curve ◽  
Line Widths

An ab initio formulation of relaxation times of various contributing processes have been observed with newer understanding in terms of electron and phonon line widths. This is dealt with the help of double time temperature-dependent Green's function via a non-perturbative approach using a crystal Hamiltonian which comprises of the effects of electrons, phonons, impurities, anharmonicities and interactions thereof. The frequency line widths is observed as an extremely sensitive quantity in the transport phenomena of high temperature superconductors (HTS) as a collection of a large number of scattering processes, namely: boundary scattering, impurity scattering, multi-phonon scattering, interference scattering, electron–phonon processes and resonance scattering. The behavior of electrons and phonons is then investigated to describe the thermal conductivity of a variety of HTS samples specially in the vicinity of transition temperature to successfully explain the spectacular dip region of thermal conductivity curve which was lacking in explanation earlier with a sound physical justification.

Calculation of dielectric polarizabilities of perovskite substrate materials for high-temperature superconductors

1994 ◽  
Vol 9 (10) ◽  
pp. 2554-2560 ◽  
Author(s):  
V.J. Fratello ◽  
C.D. Brandle
Keyword(s):  
High Temperature ◽  
Relative Permittivity ◽  
High Temperature Superconductors ◽  
Dielectric Constants ◽  
Limiting Factor ◽  
Additivity Rule ◽  
Lattice Match ◽  
Bulk Growth ◽  
Materials Used ◽  
Low Permittivity

Dielectric polarizabilities for most of the ions in known perovskites scale with the ionic volume and the valence. These ionic dielectric polarizabilities and the ion additivity rule have been used to calculate molecular dielectric polarizabilities for perovskite substrate materials used for high-temperature superconductors. Using the ion additivity rule to predict possible low permittivity compositions seems to suggest that the constraints of the perovskite structure and stoichiometry, lattice match to high-temperature superconductors, and congruent melting required for bulk growth limit the compositions to ones unlikely to be superior to the currently available materials. The most limiting factor on the relative permittivity of the perovskites is probably the close-packed nature and lack of voids in the structure. However, in nonferroelectric perovskites, the polarizabilities derived from relative permittivity data using the Clausius-Mossotti relation are significantly less than the calculated values, with deviations that correlate with degree of cation compression. Use of cation compression to reduce the polarizability shows some promise for improving dielectric constants.

Thermal conductivity and “disorder” in high temperature superconductors

1988 ◽  
Vol 67 (4) ◽  
pp. 401-404 ◽  
Author(s):  
M. Núñez Regueiro ◽  
M.A. Izbizky ◽  
P. Esquinazi
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
High Temperature Superconductors

scholarly journals Calculations of Some Doping Nanostructurations and Patterns Improving the Functionality of High-Temperature Superconductors for Bolometer Device Applications

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 97
Author(s):  
Jose C. Verde ◽  
Alberto S. Viz ◽  
Martín M. Botana ◽  
Carlos Montero-Orille ◽  
Manuel V. Ramallo
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
High Temperature Superconductors ◽  
Operational Parameters ◽  
Transition Edge ◽  
Saturation Power ◽  
Order Of Magnitude ◽  
Device Applications ◽  
Materials Used ◽  
Carrier Doping

We calculate the effects of doping nanostructuration and the patterning of thin films of high-temperature superconductors (HTS) with the aim of optimizing their functionality as sensing materials for resistive transition-edge bolometer devices (TES). We focus, in particular, on spatial variations of the carrier doping into the CuO 2 layers due to oxygen off-stoichiometry, (that induce, in turn, critical temperature variations) and explore following two major cases of such structurations: First, the random nanoscale disorder intrinsically associated to doping levels that do not maximize the superconducting critical temperature; our studies suggest that this first simple structuration already improves some of the bolometric operational parameters with respect to the conventional, nonstructured HTS materials used until now. Secondly, we consider the imposition of regular arrangements of zones with different nominal doping levels (patterning); we find that such regular patterns may improve the bolometer performance even further. We find one design that improves, with respect to nonstructured HTS materials, both the saturation power and the operating temperature width by more than one order of magnitude. It also almost doubles the response of the sensor to radiation.

Nonequilibrium effects in the thermal conductivity of Bi-based high temperature superconductors

1994 ◽  
Vol 91 (7) ◽  
pp. 571-575 ◽  
Author(s):  
H. Bougrine ◽  
S. Sergeenkov ◽  
M. Ausloos ◽  
R. Cloots ◽  
V.V. Gridin
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
High Temperature Superconductors ◽  
Nonequilibrium Effects
Sign in / Sign up

Export Citation Format

Share Document