High-Tc superconductors with nominal composition of YBa 2 Cu 3 O y and Y 1−x L x Ba 2 Cu 3 O y ( L=Li , Ce, Eu, V) were synthesis by the solid state reaction of appropriate amount of Y 2 O 3, BaO or BaCO 3, Cu 2 O , CuO, and LO x. The Cu 3+/ Cu 2+ ratio was determined by Iodometric titration and oxygen content in the oxides calculated from the ratio. The crystal structure was determined by electron and powder X-ray diffraction analysis. It shows that that ratio of Cu 3+/ Cu 2+ and the crystal structure could be changed as dopping appropriate amount of metal in the Y-Ba-Cu-O system.
Rechargeable Solid-State Copper Sulfide Cathodes for Alkaline Batteries: Importance of the Copper Valence State
