Neutron-diffraction and M�ssbauer-spectroscopy study of La 0.6 Sr 0.4 Fe 1-x Co x O 3-y ( x =0, 0.5) perovskites

The crystal and magnetic structure of La0.6Sr0.4Fe1-xCoxO3-y (x=0,0.5) perovskites was studied by neutron diffraction and Mössbauer spectroscopy. At T=2–300 K the oxides possess an oxygen-deficient, rhombohedrally distorted structure, with space group R\overline{3}c. 57Fe Mössbauer spectra below T=154 K show a regular arrangement of Fe spins, determined as a G-type antiferromagnetic structure by neutron diffraction. The mean magnetic moment at T=40 K is 1.61 μB per B-site for x=0.5, and 2.63 μB for the x=0 composition. An increase of TN and oxygen deficiency accompany the heating to 850 K. The structure of La0.6Sr0.4Fe0.5Co0.5O2.84 at 850 K is cubic with space group Pm3m.