Synthesis and investigation of reentrant oxide superconductors

The conditions for the occurrence of reentrant superconductivity in granular superconductors are studied. The parameters of synthesis of the ceramic samples of CaLaBaCu₃O _x , SrLaBaCu₃O _x and YBa_2–x Sr _x Cu₃O _y Se _z compositions, the results of their microstructure research, the elemental composition and the temperature dependence of the resistance are given. Samples are obtained, which reproducibly exhibit the reentrant superconductivity after the tens of thermal cycling. The relationship between the occurrence of reentrant superconductivity and the oxygen content in the samples was not established.