Superconductivity Versus Structural Parameters in Calcium-Doped Nd 1-x Ca x FeAsO 0.8 F 0.2 Superconductors

摘要: We have investigated experimentally how properties of NdFeAsO0.8F0.2 superconductor affected due to the substitution Ca2+/Nd3+ doping. Based on XRD data refinement, various structural parameters such as lattice parameters, bond angles, and length were studied. determined upper limit calcium solubility in phase it is restricted x ≤ 0.05. Also, we found that cell volume decreased by increasing content. According analysis, argued these reductions are variations lengths angles (O/F)-Nd-(O/F) As–Fe–As, i.e., “α, β” upon dopant. So, expected superconducting transition temperature (TC) will be sensitive doping values. Experimentally, TC our samples was reduced from 53 K (for x = 0) 48 K x = 0.01) 27 K x = 0.025) disappeared for other sample. Then, studied dependence length, pnictogen height, parameter examine available theories an empirical point view. The consistency experimental results theoretical reports based spin orbital fluctuation shows models play important role pairing mechanism iron-based superconductors.