Magnetic proeprties of the oxygen deficient perovskites La{sub 0.5}Ba{sub 0.5}Co{sub 1-x}Fe{sub x}O{sub 3-{delta}}
- ISMRA et Universite de Caen (France); and others
New perovskites characterized by a complex mixed valence of transition elements have been isolated: La{sub 0.5}Ba{sub 0.5}Co{sub 1-x}Fe{sub x}O{sub 3-{delta}} (O<1 and 0.05 < {delta} < 0.07) with the cubic symmetry, and La{sub 0.5}Ba{sub 0.5}Co{sub 0.5}Fe{sub 0.5}O{sub 2.65} with the tetragonal symmetry (a {approximately} a{sub p}, c {approximately} 2a{sub p}). The structure of the latter has been described as YBaFeCuO{sub 5-} type 90{degrees} oriented domains distributed in a stoichiometric perovskite matrix La{sub 0.5}Ba{sub 0.5}Co{sub 0.5}Fe{sub 0.5}O{sub 3}. The Moessbauer study of these phases has allowed the two species Fe(III) and Fe(IV) to be evidenced: no proof of disproportionation of Fe(IV) into Fe(III) and Fe(V) has been obtained. The cobalt mixed valence Co(III)-Co(IV) has been deduced from the Moessbauer study coupled with the chemical analysis for the oxidized samples La{sub 0.5}Ba{sub 0.5}Co{sub 1-x}Fe{sub x}O{sub 3-{delta}}, whereas the reduced phase La{sub 0.5}Ba{sub 0.5}Co{sub 0.5}Fe{sub 0.5}O{sub 2.65} is characterized by the mixed valence Co(II)-Co(III). The magnetic susceptibility measurements of La{sub 0.5}Ba{sub 0.5}Co{sub 1-x}Fe{sub x}O{sub 3-{delta}} show an evolution from an antiferromagnetic behavior for x > 0.50 with T{sub N} ranging from 142 to 218 K, to a ferromagnetic behavior for x < 0.50 with T{sub c} ranging from 120 to 150 K. The tetragonal phase La{sub 0.5}Ba{sub 0.5}Co{sub 0.5}Fe{sub 0.5}O{sub 2.65} is antiferromagnetic with T{sub N} {approximately} 480 K. All the antiferromagnetic phases exhibit a second transition at T{sub B}
- OSTI ID:
- 223713
- Journal Information:
- Journal of Solid State Chemistry, Vol. 121, Issue 1; Other Information: PBD: 5 Jan 1996
- Country of Publication:
- United States
- Language:
- English
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