The synthesis and physical properties of the new layered lanthanide alkaline earth cobalt oxides [Ln[sub 2]MCo[sub 2]O[sub 7] (Ln = Sm, Gd; M = Sr, Ba)]

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Materials Research Bulletin; (United States)

DOI:https://doi.org/10.1016/0025-5408(94)90061-2· OSTI ID:6986405

Siwen, Li; Yufang, Ren ^[1]

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1. Chinese Academy of Science, Changchun (China). Lab. of Rare Earth Chemistry and Physics

Three new oxides Sm[sub 2]SrCo[sub 2]O[sub 7], Sm[sub 2]BaCo[sub 2]O[sub 7] and Gd[sub 2]SrCo[sub 2]O[sub 7] have been successfully synthesized by a solid state reaction method. The x-ray diffraction spectra show that they are all isostructural with Sr[sub 8]Ti[sub 2]O[sub 7]. Ln[sub 2]SrCo[sub 2]O[sub 7] (Ln = Sm, Gd) crystallized in the tetragonal system, Sm[sub 2]BaCo[sub 2]O[sub 7] in the orthorhombic system. The Co-O bonds in CoO[sub 2] planes of Ln[sub 2]SrCo[sub 2]O[sub 7] are shorter than those of LnSrCoO[sub 4] (Ln = Sm, Gd), thus their d electrons are more delocalized and their electrical resistivities are smaller. The electrical resistivities versus temperature in the range 300--1100K showed that the five oxides represent weakly localized systems. In the lower temperature range, the magnetic behavior of Gd[sub 2]SrCo[sub 2]O[sub 7] and GdSrCoO[sub 4] fits the Curie-Weiss law well. The magnetic exchange reactions in the CoO sublattice of Gd[sub 2]SrCo[sub 2]O[sub 7] is ferromagnetic, but in GdSrCoO[sub 4] is antiferromagnetic. The other three oxides with Sm[sup +3] showed complex magnetic behavior which is perhaps related to the complexity of Sm[sup +3].

• OSTI ID: 6986405
• Journal Information: Materials Research Bulletin; (United States), Journal Name: Materials Research Bulletin; (United States) Vol. 29:9; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COBALT COMPOUNDS
COBALT OXIDES
FABRICATION
GADOLINIUM COMPOUNDS
GADOLINIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SAMARIUM COMPOUNDS
SAMARIUM OXIDES
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
TRANSITION ELEMENT COMPOUNDS