Oxygen deficiency effects upon structural, magnetic and electrical properties of doped manganite oxides

The effects of the oxygen deficiency on structural, magnetic and electrical properties of La(0.7)Sr(0.3)MnO(3-delta)square(delta) manganites, where sq uare is a vacancy (0 less than or equal to delta less than or equal to 0.15 ), have been investigated. The vacancy powder samples were synthesized usin g a new technique. A structural phase transition separating a rhombohedral phase and an orthorhombic phase was observed at a concentration of Mn3+ aro und 85% to 90% per Mn atom in the unit formula. These compounds exhibit fer romagnetic metallic behavior for delta < 0.1 and antiferromagnetic insulato r behavior for 0.125 less than or equal to delta less than or equal to 0.15 . A charge ordering seems to appear below T = 115 K in the La0.7Sr0.3MnO2.9 (delta = 0.1) specimen. The structural and magnetic transitions are very s ensitive to the vacancy rate.