Defect structure of Y[sub 1-y]Ca[sub y]MnO[sub 3] and La[sub 1-y]Ca[sub y]MnO[sub 3]

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

DOI:https://doi.org/10.1006/jssc.1993.1020· OSTI ID:6925923

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

---

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

Electrical conductivity and the Seebeck coefficient 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 to determine the mechanism of electrical transport and defect structure. Electrical conduction appeared to occur via a small polaron hopping mechanism for compositions with 0.30 [le] y [le] 0.80. The Seebeck coefficient data did not support the assumption that Mn is present in Ca-doped Mn perovskites only in the +3 and +4 valence states. A new defect model was developed which includes the thermally excited disproportionation of Mn[sup 3+] into Mn[sup 2+] and Mn[sup 4+] pairs. The Seebeck data were explained with this model by assuming that divalent Mn cations were site blockers in the conduction process.

• OSTI ID: 6925923
• 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
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
IONS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MANGANATES
MANGANESE COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PEROVSKITES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SEEBECK EFFECT
TRANSITION ELEMENT COMPOUNDS
VALENCE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES