用PIT(powder in tube)法在不同条件下制备MgB2样品,通过X射线衍射、扫描电子显微镜(SEM)对不同参数下制备样品的成分和微观结构进行了表征;利用Campbell法检测样品的bac-λ′关系,求得样品的超导临界转变电流密度Jc;由样品的Jc结合形貌与相成分对比分析,结果表明:长时间烧结,晶粒较大,利于导电,但缺乏钉扎作用,在外磁场下超导电流减小。长时间烧结,晶界间氧化层增厚,超导电流密度减小。
Here we report the fabrication and superconductivity of the iron-based arsenic oxide SmO1-xFxFeAs compound. X-ray diffraction （XRD） results prove that the lattice parameters a and c decrease systematically with increasing x in between 0〈x≤0.35, but when x〉0.35 the a and c increase with the decrease of x in the SmO1-xFxFeAs. The critical temperature （To） increases with increasing x in between 0.15≤x≤0.3, while x〉0.3 the Tc decreases with the increase ofx. It is found that at x=0.3 SmO0.7F0.3FeAs has the highest onset resistivity transition temperature of 55.5 K. The critical current density （Jc） value at 10 K for the obtained SmO0.TF0.3FeAs is 1.3×10^5 A/cm^2 （0 T）. Meanwhile one can estimates Hc2（0） from the slope of the Hc2（T） curve at T=-Tc （Hc2 is the upper critical field）, and for the 90% normal-state resistivity （Pn） criterion （Tc=55 K）, Hc2（0） is determined to be -253 T.
Zhiyong Liu Hongli Suo Lin Ma Min Liu Zhiping Wu Zhichao Guo Luping Han Meiling Zhou
