Microstructural refinement and enhanced transport properties in binary doped NdFeAsO superconductor

摘要: We report the synthesis of Nd1−xCaxFeAsO1−2xF2x superconductors using CaF2 as a binary dopant that provides both holes and electrons by simultaneous substitution Ca2+ ions F− at Nd3+ O2− sites, respectively. The sample with x = 0.2 exhibits maximum critical temperature (TC) 52.3 K transport current density (JC) 1240 A/cm2 12 K. An interesting feature observed for doped samples is preferential alignment (00l) planes refinement microstructure in terms grain size connectivity. NdFeAsO based are already known their very high fields field independent JC(H) performance. However, development bulk oriented large grains good connectivity has not been reported so far hence present work will be definitely step towards progress conductor development.