Acta Phys. -Chim. Sin. ›› 1992, Vol. 8 ›› Issue (03): 296-300.doi: 10.3866/PKU.WHXB19920303

• Communication • Previous Articles     Next Articles

Effects of High Valence Cations Doped on the Phase Formation and the Crystal Structure in the Bi System(II)

Chen Feng-Xiang; Li Neng; Rao Jiang-Hong; Lin Bing-Xiong; Tang You-Qi; He Jun; Zhong Shan-Jin   

  1. Department of Chemistry, Peking University, Beijing 100871; Department of Chemistry, Guangxi University
  • Received:1991-12-10 Revised:1992-01-31 Published:1992-06-15
  • Contact: Chen Feng-Xiang

Abstract: In our previous work we have found that the 2223 phase is formed more rapidly and the structural stability can be enhanced by doping high valence cation(Sn~(4+)、Sb~(5+)、V~(5+)、W~(6+)、Mo~(6+) etc.) in the Bi(Pb)SrCaCuO system. In this paper the effects of high valence cations doped on the phase formation and the crystal structure are discussed further.
The Aurivillus building and rocksalt building unit coexist in the Bi double layers. The structural variety strongly affects the structural stability. Owing to Pb~(2+) addition the probability of Aurivillus building is increased, the stability of 2223 phase can be promoted. However, the structure is still not stable, since the addition of Pb~(2+) has decreased the valence state of Bi site and the oxygen positions are not fully occupied. By doping high valence cation, especially, when the valence of Pb_x~(2+)M_y~(n+) equals to +3 the structure of the 2223 phase can be stabilized. This result has been observed with examining elemental content of 2223 phase.
The melting point of the grain boundaries are much lower after doping high valence cations, therefore the ion diffusion is more rapid and acceleration of the 2223 phase formation is observed.

Key words: Superconductor, Bi(Pb)SrCaCuO system, High valence cation doping, 2223 phase formation, Structure