Mg/B化学计量比对MgB2超导电性和磁通钉扎性能的影响

Influence of Different Mg/B Stoichiometry on Superconductivity and Flux Pinning Properties of MgB2 Bulks

摘要:

采用固相反应法制备一系列的MgxB2 (x＝0.90, 0.95, 1.0, 1.05, 1.10)超导块材，并详细研究不同Mg/B化学计量比对MgB2超导性能的影响。采用X射线衍射(XRD)仪，扫描电镜( SEM)和超导量子干涉(MPMS)仪分别对样品的物相、微观结构和超导性能进行表征。结果表明：名义组分为Mg0.95B2的样品临界电流密度Jc性能最好。由于Mg的不足，抑制了晶粒生长，同时也使得MgB2内部Mg缺位、△Tc、FWHM、Hc2和Hirr明显增加，显著改善MgB2的磁通钉扎性能

Abstract:

A series of MgxB2 (x=0.9, 0.95, 1.0, 1.05, 1.10) bulks samples were prepared by the in-situ solid-state reaction method, and then the effects of Mg/B stoichiometry on superconductivity and flux pinning properties of MgB2 were discussed. Phase purity, microstructure and superconducting properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and magnetic properties measurement system (MPMS), respectively. The results show that the sample with a nominal composition, Mg0.95B2 has the highest Jc value among all the samples. In the Mg-deficient MgB2, the degraded grains grow and lack of Mg sites are responsible to significant enhancement of the Hirr and Hc2 and the enlarged △Tc and FWHM, resulting in the great improvement of flux pinning properties of MgB2