Effect of magnetic and nonmagnetic nano metal oxides doping on the critical temperature of a YBCO superconductor

A H Salama, M El-Hofy, Y S Rammah and M Elkhatib

Abstract

Bulk superconductor samples of YBa₂Cu₃O_7−δ (YBCO) doped with nano metal oxides of Mn₃O₄, Co₃O₄, Cr₂O₃, CuO and SnO₂ respectively with 0.2 wt% are synthesized by a solid-state reaction route. The structural characterization of all samples has been carried out by x-ray diffraction (XRD) and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The XRD patterns indicate that the magnetic doping of nano metal oxides  gives a high value of orthorhombicity of the YBCO samples which is the result of high oxygen content, and consequently could give better superconducting properties contrary to the non magnetic nano oxides (CuO, SnO₂). The critical temperature (T_c) of the studied samples was found to improve by nano magnetic doping and lower with nano nonmagnetic doping. The superconducting transition temperature Tc determined from electrical resistivity measurements was found to increase for Mn₃O₄ (5.27 μB) doping and decrease for other metal oxides doping