Preparation and Electrochemical Oxygen-doping for La₂Ca_n-1Cu_nO_2n+2 by Soft Chemical Route

Abstract

Preparation and oxygen doping of La₂Ca_n-1 Cu_nO_2n+2 were investigated by applying soft chemical methods. Mixed aqueous solution of La, Ca and Cu acetates was titrated with tartaric acid aqueous solution. La₂CaCu₂O₆(n=2) could be obtained by firing the coprecipitates even at 800°C because of their homogeneously mixed state in the precipitates although the same compound had been prepared above 1000°C by solid state reaction. Both La₂Ca₂Cu₃O₈ (n=3) and La₂Ca₃Cu₄O₁₀ (n=4) could be firstly obtained at 700°C in the similar preparation method under ambient pressure. They were not stable above 800°C to decompose into mixtures of La₂CaCu₂O₆ and small amount of other compounds. Porous sintered body of La₂CaCu₂O₆ with relative density of about 15% was obtained by this preparation method. It could be effectively oxygen-doped by electrochemical method. The product showed a presence of superconducting phase with Tc around 30K.