Thermochemistry of the Y[sub 2]O[sub 3]--BaO--Cu--O system

Journal Article · Sat Oct 31 23:00:00 EST 1992 · Journal of Materials Research; (United States)

DOI:https://doi.org/10.1557/JMR.1992.2920· OSTI ID:6957982

Zhou, Z; Navrotsky, A ^[1]

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1. Department of Geological and Geophysical Sciences and Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544 (United States)

High temperature reaction calorimetry using molten lead borate as a solvent is used to study the thermochemistry of phases in the Y[sub 2]O[sub 3]--BaO--Cu--O system. Enthalpies of formation of YBa[sub 2]Cu[sub 3]O[sub [ital x]] (6[lt][ital x][lt]7), YBa[sub 2]Cu[sub 4]O[sub 8], Y[sub 2]BaCuO[sub 5], Y[sub 2]Cu[sub 2]O[sub 5], and BaCuO[sub 2.01] phases have been determined. The thermodynamic relationships among these phases at room temperature have been assessed. The results show that the 123 phase is not thermodynamically stable with respect to assemblages containing combinations of Y[sub 2]BaCuO[sub 5], Y[sub 2]Cu[sub 2]O[sub 5], BaCuO[sub 2], Y[sub 2]O[sub 3], and CuO. The fully oxidized 123 phase is not stable with respect to the 124 and the above assemblages. Reactions at room temperature are shown as follows: YBa[sub 2]Cu[sub 3]O[sub 7](s)+CuO(s) [r arrow]YBa[sub 2]Cu[sub 4]O[sub 8](s); [Delta][ital H]=[minus]31.9[plus minus]22.3 kJ mol[sup [minus]1] and YBa[sub 2]Cu[sub 3]O[sub 6.76](s)[r arrow]1/2YBa[sub 2]Cu[sub 4]O[sub 8](s) +1/4Y[sub 2]BaCuO[sub 5](s)+3/4BaCuO[sub 2.01](s); [Delta]H=[minus]78.9[plus minus]21.0 kJ mol[sup [minus]1].

• DOE Contract Number: FG02-89ER45394
• OSTI ID: 6957982
• Journal Information: Journal of Materials Research; (United States), Journal Name: Journal of Materials Research; (United States) Vol. 7:11; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ENERGY
FORMATION FREE ENTHALPY
FREE ENTHALPY
HIGH-TC SUPERCONDUCTORS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 1000-4000 K
THERMOCHEMICAL PROCESSES
THERMODYNAMIC PROPERTIES
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YTTRIUM COMPOUNDS
YTTRIUM OXIDES