Effect of MgO and Ag2O on the microstructure and superconducting properties of the (Bi,Pb)-2223 phase in the partial-melting and sintering process

摘要

The effect of MgO and Ag2O on the microstructure and superconducting properties of the (Bi,Pb)-2223 phase during sintering after partial melting has been investigated. In the Ag/oxide interface layer, a well-aligned Bi-2223 phase was preferentially formed. Both the degree of texturing and the volume fraction of the Bi-2223 phase decreased by increasing the distance from the Ag interface. Whereas, in the MgO/oxide interface layer, although well-aligned Bi-2223 grains existed at the MgO interface, a larger volume fraction of the Bi-2223 phase appeared in the center rather than at the MgO interface. The flux pinning was not clearly improved by the addition of MgO, Ag2O or PtO2 particles. However, MgO addition did not affect the formation rate of (Bi,Pb)-2223 phase, and could suppress the growth of Bi-free non-superconducting secondary phases. Ag2O or PtO2 addition resulted in coarse secondary phases, and slowed the formation rate of the Bi-2223 phase