Synthesis and characterization of La0.8Sr1.2Co0.5M0.5O4−δ (M=Fe, Mn) |
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| Authors: | H El Shinawi JF Marco FJ Berry C Greaves |
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| Institution: | aSchool of Chemistry, University of Birmingham, Birmingham B15 2TT, UK;bDepartment of Chemistry, The Open University, Milton Keynes MK7 6AA, UK;cInstituto de Quimica-Fisica “Rocasolano”, Consejo Superior de Investigaciones Cientificas, Serrano 119, 28006 Madrid, Spain |
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| Abstract: | The M4+-containing K2NiF4-type phases La0.8Sr1.2Co0.5Fe0.5O4 and La0.8Sr1.2Co0.5Mn0.5O4 have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermal analysis, neutron powder diffraction and Mössbauer spectroscopy. Oxide ion vacancies are created in these materials via reduction of M4+ to M3+ and of Co3+ to Co2+. The vacancies are confined to the equatorial planes of the K2NiF4-type structure. A partial reduction of Mn3+ to Mn2+ also occurs to achieve the oxygen stoichiometry in La0.8Sr1.2Co0.5Mn0.5O3.6. La0.8Sr1.2Co0.5Fe0.5O3.65 contains Co2+ and Fe3+ ions which interact antiferromagnetically and result in noncollinear magnetic order consistent with the tetragonal symmetry. Competing ferromagnetic and antiferromagnetic interactions in La0.8Sr1.2Co0.5Fe0.5O4, La0.8Sr1.2Co0.5Mn0.5O4 and La0.8Sr1.2Co0.5Mn0.5O3.6 induce spin glass properties in these phases. |
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| Keywords: | Ruddlesden– Popper Oxygen-deficient Neutron powder diffraction Mö ssbauer spectroscopy Magnetic order |
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