定比カチオンBi_2Sr_2CuO_δの常圧下での合成と変調構造 The Modulation and Synthesis for Bi_2Sr_2CuO_δ under Ambient Oxygen Partial Pressure
The cation stoichiometric Bi<SUB>2</SUB>Sr<SUB>2</SUB>CuOδ was successfully obtained by solid state reaction under ambient oxygen pressures (Po<SUB>2</SUB>=0.2, 1atm). The modulation period as estimated by means of X-ray powder diffraction was λ ?? 4.7b for Bi<SUB>2</SUB>Sr<SUB>2</SUB>CuOδ synthesized under Po<SUB>2</SUB>=1atm, which is shorter than that for Bi<SUB>2.125</SUB>Sr<SUB>1.875</SUB>CuO<SUB>z</SUB>(λ ?? 15b). The Bi2Sr2CuOδ synthesized under Po2=1 atm showed metallic conductivity down to 2K, whereas it done under Po<SUB>2</SUB>=0.2 atm showed superconductivity with Tc ?? 8K. By annealing in Ar, Tc was raised up to 16K. At the same time, it was newly found that the modulation is disproportionate into two types with A, λ ?? 4.7b and λ ?? 5.5b.
粉体および粉末冶金 45(7), 661-665, 1998-07-15
Japan Society of Powder and Powder Metallurgy