Effects of silver doping on magnetic levitation performance of MgB2 superconductors

Abstract

MgB2 bulk samples with the silver contents of 0, 1.5, 3.0, 4.5, 6.0, 9.0 and 12.0 wt% were fabricated at 775 °C for 3 h in Ar atmosphere by solid-state reaction method. The structural and electromagnetic properties of MgB2 samples were studied using X-ray diffraction (XRD), scanning electronic microscope (SEM), energy dispersive spectrometry (EDS), magnetic hysteresis (M-H and M-T), magnetic levitation force (Fz) and lateral force (Fx) measurements. The effect of silver addition on the levitation force performance of MgB2 has been studied for the first time in this work. All the samples indicate the onset of superconducting critical temperature (Tc,onset) in the temperature range 37.97–38.11 K. The Jc values of the 3 wt% of silver doped MgB2 sample at 15 and 25 K were 98 and 49 kA/cm2 at 0.5 T as the highest remnant Jc value was around 110 and 65 kA/cm2 at 15 and 25 K, respectively. The repulsive and attractive levitation force at 25 K increases with rising x content up to 3 wt% silver and then decreases with increasing silver addition up to 12 wt%. The maximum attractive (repulsive) levitation force values at 25 and 30 K were observed for 3 wt% silver addition as −7.09 (+19.03) and −6.03 (+15.22), respectively. These results reveal that the silver addition is the effective metallic dopant for MgB2 and can be beneficial for improving the magnetic levitation achievement of MgB2 superconductors for high field engineering applications.