We investigate the effect of Ni and Zn substitutions for Cu on the lattice parameters, phonon vibrational feature, electronic structure, as well as transport properties in Bi2Sr1.8La0.2CuOy. The experimental data show that both Xi and Zn are soluble in the Bi2Sr1.8La0.2CuOy material up to about 10% of the Cu content. In Bi2Sr1.8La0.2Cu1-xNi xOy system, the superconducting critical temperature Tc decreases linearly with Ni concentration and the rate of Tc decrease is around 2.5K/at.%. while for Bi2Sr1.8La0.2Cu1-xNi xOy system the dependence of Tc on the Zn dopant concentration deviates from a linear behavior and the Zn substitution suppresses the Tc much stronger than the Ni substitution. The comparison of the phonon vibrational feature of the apical oxygen atoms in the CuO6 octahedron between the Bi2Sr1.8La0.2Cu1-xNi xOy and Bi2Sr1.8La0.2Cu1-xNi xOy systems shows that the Zn substitution leads to a more serious structure distortion than the Ni substitution. In addition, the electronic structures of the two doped systems were compared using XPS spectrum. The results show that the Zn substitution reduces Cu oxidation level more remarkably than the Ni substitution. Some possible explanations for the stronger suppression of Tc by the Zn substitution than by the Ni substitution are provided, based on these experimental results.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)