细化Sr－Ca－Cu－O相制备高J_cBi－2223／Ag带材

Preparation of High J_c Bi-2223/Ag Tapes by Sr-Ca-Cu-O Phase Refining

用预烧结的粉末灌银管，且在８２０℃～８３５℃温区内逐步升温，对于细化Ｓｒ－Ｃａ－Ｃｕ－Ｏ相非常有效，有助于提高Ｂｉ－２２２３／Ａｇ带材的Ｊｃ值。与通常的高温烧结粉相比，在７７Ｋ和零场下带材的Ｊｃ值可提高一倍。扫描电镜观察和ｘ射线衍射分析表明：（１）用预烧粉末灌银管不仅可细化Ｓｒ－Ｃａ－Ｃｕ－Ｏ相，而且能很好地抑制铅的挥发；（２）在８２０℃～８３５℃温区内逐步升温不仅可增加２２２３相的比份，而且能有效地抑制Ｓｒ－Ｃａ－Ｃｕ－Ｏ相的长大和聚集。

Abstract Packing with presintered powder and slow heating in the temperature range 820～835℃ were observed to be very effective in the refining of Sr-Ca-Cu-O phases, therefore helping in enhancing Jc of Bi-2223/Ag tapes. Jc at 77 K and 0 T was doubled with respect to similar tapes prepared by conventional sintering at higher temperature. SEM observation and X-ray diffraction confirmed that: (1) packing with presintered powder not only refines the Sr-Ca-Cu-O phases but also supresses lead volatilization greatly, and (2) slow heating in the temperature range 820～835℃ not only guarantees the formation of a high volume fraction of the 2223 phase but also effectively suppresses the growth and aggregation of Sr-Ca-Cu-O phases.