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), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 93:2; ISSN 0022-4596; ISSN JSSCB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
665411 -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
CALORIMETRY
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DISPERSIONS
ENTHALPY
EXPERIMENTAL DATA
FORMATION HEAT
INFORMATION
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LATTICE PARAMETERS
MIXTURES
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
RARE EARTH COMPOUNDS
REACTION HEAT
REDUCTION
SCATTERING
SOLID SOLUTIONS
SOLUTIONS
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTORS
SYNTHESIS
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VACANCIES
X-RAY DIFFRACTION