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Structural and Magnetic Characterisation of La 1+ x Sr 1– x Co 0.5 M 0.5 O 4± δ (M = Cr, Mn)
Author(s) -
El Shinawi Hany,
Greaves Colin
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900202
Subject(s) - tetragonal crystal system , neutron diffraction , crystallography , crystal structure , x ray crystallography , materials science , powder diffraction , oxide , magnetic susceptibility , diffraction , solid solution , chemistry , analytical chemistry (journal) , physics , chromatography , optics , metallurgy
The K 2 NiF 4 phases La 1+ x Sr 1– x Co 0.5 Cr 0.5 O 4± δ ( x = 0, 0.15) and La 1+ x Sr 1– x Co 0.5 Mn 0.5 O 4± δ ( x = 0, 0.2) have been synthesised and examined by X‐ray powder diffraction, thermal analysis, neutron powder diffraction and magnetic susceptibility measurements. Mn 3+ /Co 3+ and Cr 3+ /Co 3+ states predominate in the oxidised forms. Structural stability and crystal symmetry are retained under reducing conditions which cause reduction of Co 3+ into Co 2+ and the creation of oxide ion vacancies within the equatorial planes of the K 2 NiF 4 structure. Excess oxygen in La 1.2 Sr 0.8 Co 0.5 Mn 0.5 O 4.1 is accommodated in the ideal interstitial positions (0, 0.5, 0.25) of the tetragonal structure of these materials in an oxygen/air atmosphere. No long‐range magnetic order has been observed because of competing AFM and FM interactions in these B‐site disordered materials.