Structure of Metastable Sr0.8Dy0.2Co3-delta Phases and Their Electrical and Magnetic Properties

Dudnikov, V. A.; Vereshchagin, S. N.; Solov'ev, L. A.; Gavrilkin, S. Yu; Tsvetkov, A. Yu; et al.// Journal Of Experimental And Theoretical Physics//

Polycrystalline Sr0.8Dy0.2Co3 – δ complex cobalt oxides with a different amount of oxygen (δ = 0.26, 0.44, 0.46) have been prepared by solid-state synthesis. An increase in oxygen deficiency causes the brownmillerite phase to appear in the perovskite structure, which significantly changes its properties. At δ = 0.46, the content of the brownmillerite phase reaches 38%. A comparative analysis of the magnetic and transport properties of synthesized samples has been carried out. The asymptotic Curie temperature changes sign from positive at δ = 0.26 to negative at δ = 0.46. The magnetoresistance of the sample with δ = 0.46 is negative and exceeds 40% at T = 10 K. The temperature dependence of resistivity is characteristic of semiconductors, and the absolute values for samples at low temperatures differ almost tenfold.