ソフト化学法によるLa_2Ca_<n-1>Cu_nO_<2n+2>の合成と電気化学的酸素ドープ Preparation and Electrochemical Oxygen-doping for La_2Ca_<n-1>Cu_nO_<n+2> by Soft Chemical Route
Preparation and oxygen doping of La<SUB>2</SUB>Ca<SUB>n-1</SUB> Cu<SUB>n</SUB>O<SUB>2n+2</SUB> were investigated by applying soft chemical methods. Mixed aqueous solution of La, Ca and Cu acetates was titrated with tartaric acid aqueous solution. La<SUB>2</SUB>CaCu<SUB>2</SUB>O<SUB>6</SUB>(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 La<SUB>2</SUB>Ca<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>8</SUB> (n=3) and La<SUB>2</SUB>Ca<SUB>3</SUB>Cu<SUB>4</SUB>O<SUB>10</SUB> (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 La<SUB>2</SUB>CaCu<SUB>2</SUB>O<SUB>6</SUB> and small amount of other compounds. Porous sintered body of La<SUB>2</SUB>CaCu<SUB>2</SUB>O<SUB>6</SUB> 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.
粉体および粉末冶金 44(2), 132-136, 1997-02-15
Japan Society of Powder and Powder Metallurgy