Energetics of La sub 2 minus x Sr sub x CuO sub 4 minus y solid solutions (0. 0 le x le 1. 0)
- Princeton Univ., NJ (United States)
- International Business Machines Corp., Yorktown Heights, NY (United States)
Compounds in the La{sub 2{minus}x}Sr{sub x}CuO{sub 4{minus}y} series have been synthesized in the single phase range 0 {le} x {le} 1. High temperature solution calorimetry in molten lead borate was used to determine the heats of formation from oxide components. The enthalpy of formation becomes more exothermic with increasing Sr substitution 0 {le} x {le} 0.15 and then remains approximately constant for 0.15 {le} x {le} 1. This trend can be explained by the balance between the (formal) substitution La{sup 3+} + Cu{sup 2+} = Sr{sup 2} + Cu{sup 3+} and the loss of oxygen, keeping copper formally divalent but creating oxygen vacancies. Using a transposed temperature drop method, the heat of oxidation was determined to be {minus}129 kJ/(mole O{sub 2}) by a comparison of samples with the same strontium content but a different oxygen content.
- OSTI ID:
- 5735108
- Journal Information:
- Journal of Solid State Chemistry; (United States), Vol. 93:2; ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COPPER OXIDES
FORMATION HEAT
LANTHANUM OXIDES
STRONTIUM OXIDES
SUPERCONDUCTORS
CALORIMETRY
CHEMICAL PREPARATION
CHEMICAL REACTIONS
EXPERIMENTAL DATA
LATTICE PARAMETERS
OXIDATION
REDUCTION
SOLID SOLUTIONS
TEMPERATURE RANGE 0400-1000 K
VACANCIES
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DISPERSIONS
ENTHALPY
INFORMATION
LANTHANUM COMPOUNDS
MIXTURES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
RARE EARTH COMPOUNDS
REACTION HEAT
SCATTERING
SOLUTIONS
STRONTIUM COMPOUNDS
SYNTHESIS
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
665411 - Basic Superconductivity Studies- (1992-)