Effects of A-site substitution on the structure and magnetic properties of Bi0.15Sr0.85-yAeyCo1-xFexO3-? perovskites
2009 (English)In: Solid State Sciences, ISSN 1293-2558, Vol. 11, no 11, 1945-1954 p.Article in journal (Refereed) Published
The effects of partial substitution of Sr2+ by Ca2+ and Ba2+ on the A-site of oxygen deficient perovskites, Bi0.15Sr0.85-yAeyCo1-xFexO3-?, where y = 0.29 for Ae = Ba and y = 0.17 for Ae = Ca, and 0.0 ? x ? 1.0, have been investigated. The differing ionic size of the Ca2+ and Ba2+ cations influences both the crystal structure and the properties of the materials. The smaller Ca2+ cation favoured formation of an oxygen vacancy ordered perovskite superstructure (I4/mmm, a = 2ap, c = 4ap), meanwhile the presence of the larger Ba2+ cation promoted a disordered simple cubic structure (Pm-3m, a = ap) that was also found for all Fe containing samples, i.e. x ? 0.25. The samples were studied with PXRD, NPD, TGA, HREM and magnetic susceptibility measurements. All as-prepared samples exhibited long range G-type antiferromagnetic ordering. The effect of oxygen annealing was dramatic for the Bi0.15Sr0.68Ca0.17Co1-xFexO3-? series with a disappearance of magnetic order for x ? 0.25 linked to increasing spin glass properties. The oxygen content of the Bi0.15Sr0.56Ba0.29Co1-xFexO3-? as-prepared materials was generally higher than their Ca substituted counterparts, and the long range antiferromagnetic order was more resistant to oxygen annealing.
Place, publisher, year, edition, pages
2009. Vol. 11, no 11, 1945-1954 p.
vacancies, neutron diffraction, perovskite supercell, antiferromagnetic, spin glass
IdentifiersURN: urn:nbn:se:su:diva-36653ISI: 000272116800018OAI: oai:DiVA.org:su-36653DiVA: diva2:290393
övrigt antal författare 3st.2010-01-262010-01-252010-10-12Bibliographically approved