Effect of MgO and Ag 2O on the microstructure and superconducting properties of the (Bi,Pb)-2223 phase in the partial-melting and sintering process

Abstract

The effect of MgO and Ag 2O 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, Ag 2O or PtO 2 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. Ag 2O or PtO 2 addition resulted in coarse secondary phases, and slowed the formation rate of the Bi-2223 phase.