热处理气氛对(Bi,Pb)_2Sr_2Ca_2Cu_3O_y超导带材晶粒尺寸及相组成的影响

Effect of heat treatment atmosphere on grain size and phase composition of (Bi,Pb)_2Sr_2Ca_2Cu_3O_y superconducting tapes

采用粉末装管法(PIT)制备(Bi,Pb)2Sr2Ca2Cu3Oy(Bi-2223)超导带材,通过X射线衍射仪、扫描电镜研究热处理气氛对Bi-2223晶粒尺寸、结晶度及相组成的影响。研究结果表明:采用空气热处理有利于Bi-2223晶粒的长大;采用7.5%O2-Ar气氛热处理带材中存在较少的非超导相,且Bi-2223的结晶度较高;通过一种复合气氛热处理(热处理过程中使用两种气氛),带材Bi-2223晶粒尺寸较大且非超导相较少。工艺优化后最终带材的临界电流密度超过20000A/cm2(自场,77K)。

（Bi,Pb）2Sr2Ca2Cu3Oy（Bi-2223） superconducting tapes were made by powder-in-tube（PIT） method.X-ray diffraction（XRD） and scanning electron microscopy（SEM） were employed to study the effect of heat treatment atmosphere on grain size,crystallinity and phase composition of the Bi-2223 tapes.The experiment results show that annealing in air increases grain size of Bi-2223.Sintering in 7.5%O2-Ar reduces the non-superconducting phase and improves crystallinity.It is profitable to reduce non-superconducting phase and increase grain size of Bi-2223 by a combined heat treatment method（ using two kinds of different atmospheres during heat treatment）. The critical current density of the tapes prepared by controlling heat treatment procedure is 2.0 ×10^4 A/cm2 at 77K, self-field.