高T_cBi－Pb－Sr－Cu－Ca－O系氧化物超导材料的Meissner效应和磁屏蔽效应

MEISSNER EFFECT AND MAGNETIC SHIELDING EFFECT OF HIGH T_c Bi-Pb-Sr-Cu-Ca-O SYSTEM OXIDE SUPERCONDUCTIC MATERIAL

对高ＴｃＢｉ－Ｐｂ－ｓｒ－Ｃｕ－Ｃａ－Ｏ系氧化物超导材料的多晶块状、多晶粉末状和单晶等三种样品的Ｍｅｉｓｓｎｅｒ效应和磁屏蔽效应进行了仔细测量和分析．块状样品具有较强的磁屏蔽能力，在ＺＦＣ（Ｚｅｒｏ－ＦｉｅｌｄＣｏｏｌｅｄ）和ＦＣ（ＦｉｅｉｄＣｏｏｌｅｄ）两种过程中，超导体的体积比之差最大约１０％左右（μ０Ｈ≈２００Ｘ１０－４Ｔ）；粉末样品和单晶样品的磁屏蔽能力很小（７７Ｋ）．

Meissner effect and magnetic shieldind effect have been measured and disscussed on high Tc Bi-Pb-Sr-Cu-Ca-O system oxide superconductive polycrystalline bulk sample,powder sample and single crystale sample. The magnetic shielding ability of bulk sample is stronger than that of the powder and single crystale sample,the magnetic shielding ability of the powder and single crystale sample is very small (77 K). In ZFC and FC process the greatest difference superconductive volume fraction of bulk sample is around 10% (μH≈200 X 10-4 T).