Preparation of ceramics (Sr,Ba){sub}2CuO{sub}3 by conventional solid-state reaction

摘要

Bulk superconductors Sr{sub}(2x)Ba{sub}xCuO{sub}3 were synthesized by a solid-state reaction of stoichiometric mixtures of copper oxide and carbonates of Sr and Ba in the ambient pressure. The samples with x>0.8, which are prepared by sintering at 930-960℃ in an oxygen flow after pre-sintering at 800℃ in vacuo, have the "high-pressure" tetragonal form of Sr{sub}2CuO{sub}3, while with x<0.8 the orthohombic structure is more stable. The as-synthesized sample of Sr{sub}0.8Ba{sub}1.2CuO{sub}3 is non-superconducting in contrast to the high-pressure" obtained samples and is converted to the orthohombic phase by heating at 750℃ in 1 atm N{sub}2.