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

摘要

Polycrystalline Sr0.8Dy0.2Co3 - delta complex cobalt oxides with a different amount of oxygen (delta = 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 delta = 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 delta = 0.26 to negative at delta = 0.46. The magnetoresistance of the sample with delta = 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.