Fe-Doping Effect on the Bi3Ni Superconductor Microstructure

The substitution effects of Fe ion on the structure of the intermetallic Bi3Ni1-xFex (0 ≤ x ≤ 0.10) superconductor were studied. The morphology of samples consists of an inhomogeneous laminar slab-like microstructure. The main phase corresponds to Bi3Ni1-xFex with an orthorhombic structure (Pnma), but with very small quantities of impurities of BiNi and Bi as revealed by X-ray diffraction. SEM and AFM reveal that the Bi3Ni1-xFex phase consists of two regions. One region is Bi richer and Ni and Fe poorer than the other region. Raman spectroscopy revealed two phonon modes at room temperature. No significant changes were observed in the spectra with Fe doping and in different regions of the Bi3Ni1-xFex phase. Superconductivity is observed below a transition temperature TC = 4 K and regardless of iron doping.