Defect structure of Y[sub 1-y]Ca[sub y]MnO[sub 3] and La[sub 1-y]Ca[sub y]MnO[sub 3]. II. Oxidation-reduction behavior

Journal Article · Fri Jan 01 04:00:00 EST 1993 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1006/jssc.1993.1021· OSTI ID:6773087

Stevenson, J W; Nasrallah, M M; Anderson, H U; Sparlin, D M ^[1]

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1. Univ. of Missouri, Rolla (United States)

Electrical conductivity, Seebeck coefficient, and thermogravimetric behavior of compositions in the system Y[sub 1-y]Ca[sub y]MnO[sub 3] and La[sub 1-y]Ca[sub y]MnO[sub 3] were studied as functions of temperature and ambient oxygen activity in order to determine the mechanism of electrical transport and defect structure. Compositions in Y[sub 1-y]Ca[sub y]MnO[sub 3] exhibited very slight oxygen activity-dependent behavior as the ambient oxygen activity was reduced. A defect model which includes the thermally excited disproportionation of Mn[sup 3+] into Mn[sup 2+] and Mn[sup 4+] pairs was applied to the oxygen-activity-dependent data for La[sub 0.80]Ca[sub 0.20]MnO[sub 3] and La[sub 0.60]Ca[sub 0.40]MnO[sub 3]. For these compositions, the experimentally observed dependence of oxygen stoichiometry, electrical conductivity, and Seebeck coefficient upon ambient oxygen activity was explained using this model.

• OSTI ID: 6773087
• Journal Information: Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 102:1; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRICAL PROPERTIES
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MANGANATES
MANGANESE COMPOUNDS
MEASURING METHODS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REDOX REACTIONS
SEEBECK EFFECT
STOICHIOMETRY
TEMPERATURE DEPENDENCE
THERMOGRAPHY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES