抄録
High-purity polycrystalline samples of Bi2.1Sr1.9-xLaxCuO6+d 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 Bi17Sr16Cu7Oy, CuO, Bi2Sr3Cu2Oy, The dependence of the superconducting transition temperature Tc(onset) with increasing La content has a parabolic-like behavior with maximum Tc(onset)=16.6 K at x=0.3. We heve investigated the effect of La substitution for Sr on Raman spectra of Bi2.1Sr1.9-xLaxCuO6+d. The apical-oxygen phonon at-630cm-1 softens by -20cm-2 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.
