Cerium effect on electrical properties and phase composition of Y1-xCex4+Ba2Cu3Oy(X=0,05-0,3) ceramics

Y-Ce-Ba-Cu-O system dense polycrystalline samples are produced by solid-phase synthesis. X-ray phase analysis and electron microscopy methods are used to study phase composition and structure defects of samples obtained depending on their heat treatment conditions. Analysis of electron-microscopic images showed that Ce atoms don't replace Y, but are localized in Cu-planes, their distribution for nonannealed samples is discovered ruptures in Cu-layers are observed, oxygen annealing causes complete oxidation of Ce3+ up to Ce4+, while is orderly arranged in Cu-layers up to formation of sharply defined sections of BaCeO3 new phase. Electrical resistance temperature dependence is measured ρ(T): Tc low value in non-annealed sampled is due to oxygen redistribution in presence of Ce4+