中文摘要：

以纳米Al粉为掺杂物质，借助超声分散，较好地解决了纳米Al粉的团聚及其与B粉的均匀混合问题，制备出了1mol％、2mol％、5mol％、8mol％纳米Al粉掺杂的MgB2超导块材，并对掺杂效果和机理进行了研究．物相和显微结构分析表明，Al能够替代Mg进入MgB2晶格内，并导致MgB2的晶胞参数a、c逐渐降低，其中c的降低幅度较大．随着Al掺量的增加，MgB2的临界温度疋逐渐降低，由未掺杂时的38．5K降低至掺杂8mol％Al时的35．5K．超导电性研究结果表明，纳米Al粉掺杂，在低温、高场、低掺杂量的条件下可以改善MgB2的超导性能，掺杂量过大反而抑制MgB2的超导性能，2mol％的纳米Al粉掺杂效果最好．

英文摘要：

Nano-size Al powders were dispersed by ultrasonic vibrations to avoid reuniting and doped to the MgB2 bulk material uniformly. The effects and mechanism of doping were studied. The phase analysis and microstructure analysis show that Al atoms can dope into the lattice of MgB2 and substitute the site of Mg atoms. With the increase of addition, the crystal parameters a and c of MgB2 decrease gradually and the value of c depresses more, and the critical temperature Tc of MgB2 depresses too. The value of Tc is 35.5K for the superconductor with 8mo1% addition, while 38.5K for the pure MgB2 bulk superconductor. The results of our research demonstrate that the superconductivity of MgB2 with nano-Al doping is improved at the conditions of low temperature, high magnetic field and low level addition, the high level addition can restrain the superconductivity of MgB2; the effects are the best when the value of nano-Al dopant is 2mo1%.