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Title: Future of high-critical-temperature superconducting ceramics.

Abstract

No abstract prepared.

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
915038
Report Number(s):
ANL/CMT/JA-59935
Journal ID: ISSN 0002-7812; ACSBA7; TRN: US200817%%73
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Am. Ceram. Soc. Bull.; Journal Volume: 86; Journal Issue: 6 ; 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; FORECASTING; CERAMICS; HIGH-TC SUPERCONDUCTORS

Citation Formats

Maroni, V. A., and Chemical Engineering. Future of high-critical-temperature superconducting ceramics.. United States: N. p., 2007. Web.
Maroni, V. A., & Chemical Engineering. Future of high-critical-temperature superconducting ceramics.. United States.
Maroni, V. A., and Chemical Engineering. Mon . "Future of high-critical-temperature superconducting ceramics.". United States. doi:.
@article{osti_915038,
title = {Future of high-critical-temperature superconducting ceramics.},
author = {Maroni, V. A. and Chemical Engineering},
abstractNote = {No abstract prepared.},
doi = {},
journal = {Am. Ceram. Soc. Bull.},
number = 6 ; 2007,
volume = 86,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The experimentally determined current-voltage characteristics of high-T{sub c} superconducting ceramics exhibiting the {open_quotes}peak-effect{close_quotes} in the magnetic field dependence of the transport critical-current density were described in terms of thermally activated flux creep at grain boundaries; taking into account the collective pinning of intergranular vortices. The peak effect was explained by considering the increase of the intergrain pinning potential at intermediate fields through the interaction of intergranular (Josephson type) vortices and intragranular (Abrikosov) vortices. The magnetic field dependences of the effective pinning potential and of the collective pinning exponent were experimentally determined, and the features of the I-V curves were explainedmore » through these dependences.« less
  • The authors have studied the pre-onset deviation-from-linearity region, the transitional regime, and the foot region in the resistance vs temperature behavior of high-Critical Temperature oxide superconductors, employing time-varying magnetic fields and carefully controlled precise temperatures. They have previously shown that the best value of critical temperature can be extrapolated from the magnetic field induced divergence of the resistance vs inverse absolute temperature data as derived from the transitional and/or foot regions, and that these data are in accord with results from Hall effect studies. The pre-onset region however, shows a differing non-diverging behavior. However sweep magnetic field studies show that,more » as a function of field, differential resistance data points corresponding to temperature values in the normal state, pre-onset state, and transitional state all lie on a straight line, whereas data points corresponding to the foot region and zero resistance region deviate from this line. The authors interpret these data to indicate that the phenomena that govern the pre-onset state constitute a different stage of processes that arise initially in the normal state at temperature slightly greater than the critical temperature, and continue in the transitional state at temperature slightly less than the critical temperature. They believe that the lifetime of the particle that mediates Cooper-pairing establishes these different stages of the process leading to superconductivity in the cuprates.« less
  • We have grown highly oriented LaBa{sub 2}Cu{sub 3}O{sub {ital y}} (110)/Ag (111) bilayers on sapphire (11{bar 2}0). This structure constitutes a potentially excellent buffer layer for the growth of 1-2-3 ceramic oxides on sapphire substrates. This bilayer does not show superconductivity in resistive measurements. A DyBa{sub 2}Cu{sub 3}O{sub {ital y}} film grown on this bilayer also exhibited (110) orientation.
  • Since the discovery of high-transition temperature ([gt]90K) superconductors, attempts have been made to find additional oxide compounds with this superconducting property. This paper reports on several new superconductors with critical temperatures of over 90K which have been discovered during the past few years. Two such ceramics are YBa[sub 2]Cu[sub 3]O[sub 7 [minus] x] and superconductors made with bismuth (Bi[sub 1. 7]PbCa[sub 2]Sr[sub 2]CaO[sub x]). The multiphase microstructure of these materials are very complex and exceedingly difficult to property prepare for metallographic evaluation. Further, some of the microstructural phases present in these materials react with water in the alumina polishing abrasivesmore » slurries. Metallographic specimen preparation of these ceramic superconductors by conventional methods is a laborious task with reproducible results often difficult to achieve. Consequently, a preparation technique based on the use of an automatic polishing machine is investigated. A reliable metallographic preparation procedure has been developed using the Struers Prepamatic automatic polishing machine. This procedure provides rapid, high-quality, reproducible results with a considerable savings of manual labor. Additionally, a simple modification to the polishing machine configuration provided a means of sample preparation with nonaqueous liquids. The advantages of this automatic polishing procedure will be described and illustrated with photomicrographs.« less
  • In comparison with the [open quotes]classical[close quotes] Kim-Anderson model for the current-voltage characteristics of type-II superconductors, another model with a less sharp pinning potential is presented. In addition to the approximate solution, for currents close to the critical one, a complete solution of this model is derived, which better fits the experimentally obtained current-voltage characteristics.