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Title: Phase equilibria among the superconductors in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system

Abstract

The enthalpy of formation of Y[sub 2]Ba[sub 4]Cu[sub 7]O[sub 14.864] at room temperature has been determined by using high-temperature reaction calorimetry. The standard enthalpy of formation of the 247 phase is [Delta]H[sup o][sub f]=[minus]5463[plus minus]18 hthinsp;kJ hthinsp;mol[sup [minus]1]. Phase relationships among the superconductors, namely, the 123, 124, and 247, are assessed. It is intrinsic that impurity phases, such as Y[sub 2]Cu[sub 2]O[sub 5], BaCuO[sub 2], CuO, etc., coexist with the superconductors at equilibrium. Equilibria among the superconductor phases in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system have been determined. The results show that, at the 124 bulk composition, the 247 phase coexists with the excess CuO in a narrow area of p[sub O[sub 2]][approximately]T space confined by the stability fields of the 124 phase and a mixture of the 123+CuO. The standard free energies of carbonation and hydration of the 247 phase are also determined, which are [minus]629[plus minus]13 hthinsp;kJ hthinsp;mol[sup [minus]1] and [minus]873[plus minus]45 hthinsp;kJ hthinsp;mol[sup [minus]1], respectively. Like the 123 and 124 phases, the 247 phase is thermodynamically unstable for corrosion by water vapor and carbon dioxide in ambient atmosphere. [copyright] [ital 1999 Materials Research Society.]

Authors:
;  [1]
  1. (Princeton Materials Institute and Department of Geological and Geophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States))
Publication Date:
OSTI Identifier:
6109000
Alternate Identifier(s):
OSTI ID: 6109000
Resource Type:
Journal Article
Journal Name:
Journal of Materials Research
Additional Journal Information:
Journal Volume: 14:9; Journal ID: ISSN 0884-2914
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BARIUM COMPOUNDS; BARIUM OXIDES; COPPER COMPOUNDS; COPPER OXIDES; CORROSION; FORMATION HEAT; HIGH-TC SUPERCONDUCTORS; OXYGEN COMPOUNDS; PHASE STUDIES; YTTRIUM COMPOUNDS; YTTRIUM OXIDES; ALKALINE EARTH METAL COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; ENTHALPY; OXIDES; PHYSICAL PROPERTIES; REACTION HEAT; SUPERCONDUCTORS; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENT COMPOUNDS; TYPE-II SUPERCONDUCTORS 360202* -- Ceramics, Cermets, & Refractories-- Structure & Phase Studies

Citation Formats

Zhou, Z., and Navrotsky, A. Phase equilibria among the superconductors in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system. United States: N. p., 1999. Web. doi:10.1557/JMR.1999.0474.
Zhou, Z., & Navrotsky, A. Phase equilibria among the superconductors in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system. United States. doi:10.1557/JMR.1999.0474.
Zhou, Z., and Navrotsky, A. Wed . "Phase equilibria among the superconductors in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system". United States. doi:10.1557/JMR.1999.0474.
@article{osti_6109000,
title = {Phase equilibria among the superconductors in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system},
author = {Zhou, Z. and Navrotsky, A.},
abstractNote = {The enthalpy of formation of Y[sub 2]Ba[sub 4]Cu[sub 7]O[sub 14.864] at room temperature has been determined by using high-temperature reaction calorimetry. The standard enthalpy of formation of the 247 phase is [Delta]H[sup o][sub f]=[minus]5463[plus minus]18 hthinsp;kJ hthinsp;mol[sup [minus]1]. Phase relationships among the superconductors, namely, the 123, 124, and 247, are assessed. It is intrinsic that impurity phases, such as Y[sub 2]Cu[sub 2]O[sub 5], BaCuO[sub 2], CuO, etc., coexist with the superconductors at equilibrium. Equilibria among the superconductor phases in the Y[sub 2]O[sub 3][endash]BaO[endash]Cu[endash]O system have been determined. The results show that, at the 124 bulk composition, the 247 phase coexists with the excess CuO in a narrow area of p[sub O[sub 2]][approximately]T space confined by the stability fields of the 124 phase and a mixture of the 123+CuO. The standard free energies of carbonation and hydration of the 247 phase are also determined, which are [minus]629[plus minus]13 hthinsp;kJ hthinsp;mol[sup [minus]1] and [minus]873[plus minus]45 hthinsp;kJ hthinsp;mol[sup [minus]1], respectively. Like the 123 and 124 phases, the 247 phase is thermodynamically unstable for corrosion by water vapor and carbon dioxide in ambient atmosphere. [copyright] [ital 1999 Materials Research Society.]},
doi = {10.1557/JMR.1999.0474},
journal = {Journal of Materials Research},
issn = {0884-2914},
number = ,
volume = 14:9,
place = {United States},
year = {1999},
month = {9}
}