Effects of Fe doping on crystal structure, superconductivity and Raman spectra in SmBa2Cu3O7−δ systems

SmBa2Cu3−xFexO7−δ (SBCFO) (x = 0.0–0.4) systems are prepared by the usual solid-state reaction technique. The effect of Fe doping on the structure, electronic transport properties and Raman spectra of SBCFO systems have been investigated. The X-ray measurement indicates that Fe ions have a significant effect on the main crystalline structure and SBCFO undergoes a structure phase transition from orthorhombic to tetragonal between x = 0.05 and 0.1. The superconducting (SC) transition temperature Tc decreases with the increase of Fe-doping content; an insulator transition appears in high doping content samples (x ⩾ 0.3). We have discussed the Raman shifts and intensity of the five normal phonon peaks and the other modes at 229 and 589 cm−1 which result from oxygen deficiency in the chain structure. These investigations reveal that the electrical transport properties and Raman spectra of SmBa2Cu3−xFexO7−δ composites obviously depend on O–T transition induced by the Fe doping.

► Fe ions affect significantly the lattice parameter of the SmBa2Cu3−xFexO7−δ ceramic.
► The superconducting transition temperature decreases with increasing Fe content.
► Raman spectra of the samples obviously depend on O–T transition induced by Fe doping.