錯体重合法によるBi_<2.1>Sr_<1.9-x>La_xCuO_<6+d>の合成とそのラマン散乱 Polymerized Complex Synthesis and the Raman Scattering of Bi_<2.1>Sr_<1.9-x>La_xCuO_<6+d>
High-purity polycrystalline samples of Bi<SUB>2.1</SUB>Sr<SUB>1.9-x</SUB>La<SUB>x</SUB>CuO<SUB>6+d</SUB> with x=0-1 have been prepared by the polymerized complex method X-ray powder diffraction and complex magnetic susceptibility mesurements have shown that the samples are of a single-bulk Bi2201 phase without any impurity such as Bi<SUB>17</SUB>Sr<SUB>16</SUB>Cu<SUB>7</SUB>O<SUB>y</SUB>, CuO, Bi<SUB>2</SUB>Sr<SUB>3</SUB>Cu<SUB>2</SUB>O<SUB>y</SUB>, The dependence of the superconducting transition temperature T<SUB>c</SUB>(onset) with increasing La content has a parabolic-like behavior with maximum T<SUB>c</SUB>(onset)=16.6 K at x=0.3. We heve investigated the effect of La substitution for Sr on Raman spectra of Bi<SUB>2.1</SUB>Sr<SUB>1.9-x</SUB>La<SUB>x</SUB>CuO<SUB>6+d</SUB>. The apical-oxygen phonon at-630cm<SUP>-1</SUP> softens by -20cm<SUP>-2</SUP> with increasing La content, when x goes from 0 to 1. This change can be interpreted in terms of the charge redistribution induced by decreasing the Cu and Bi valences with La doping.
粉体および粉末冶金 44(2), 137-141, 1997-02-15
Japan Society of Powder and Powder Metallurgy