材料期刊网

Here we report the fabrication and superconductivity of the iron-based arsenic oxide SmO_1-xF_xFeAs 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 SmO_1-xF_xFeAs. The critical temperature (T_c) increases with increasing x in between 0.15≤x≤0.3, while x>0.3 the T_c decreases with the increase of x. It is found that at x=0.3 SmO_0.7F_0.3FeAs has the highest onset resistivity transition temperature of 55.5 K. The critical current density (J_c) value at 10 K for the obtained SmO_0.7F_0.3FeAs is 1.3×10⁵ A/cm² (0 T). Meanwhile one can estimates H_c2(0) from the slope of the H_c2(T) curve at T=T_c (H_C2 is the upper critical field), and for the 90% normal-state resistivity (ρ_n) criterion (T_c=55 K), H_c2(0) is determined to be ~253 T.