Study of the Influence of MgO Nano-Oxide Addition on the Electrical and Mechanical Properties of (Cu0.25Tl0.75)-1234 Superconducting Phase

The effect of nano-size MgO (40-60 nm) addition on the physical properties of polycrystalline (Cu(0.25)Tl(0.75))-1234 was studied. The MgO-concentration (x) varied from 0.0 to 1.0 wt.% of the sample's total mass. X-ray analysis, granular structure examination, energy dispersive X-ray spectroscopy, electrical resistivity, critical current density at different applied magnetic fields and Vickers microhardness measurements were carried out to study the performance of these samples. Phase examination by X-ray diffraction indicated that MgO-addition enhanced the (Cu(0.25)Tl(0.75))-1234 phase formation till x=0.6 wt.%. Granular investigation by scanning electron microscope reveled that both number and size of voids decreased as x increased from 0.0 to 0.6 wt.%. These results were supported by the sample's porosity calculation. The superconducting transition temperature and critical current density were found to have optimum values at x=0.6 wt.%. Furthermore, the Vickers microhardness increased till x=0.6 after that it decreased with further increase in x.