The effect of nano-Pt/nano-SiC co-additions on superconducting properties of bulk MgB2

Abstract

This research presents a detailed analysis and discussion of the crystallographic, flux pinning mechanism, the microstructure and superconducting properties of nano-Pt/nano-SiC co-added (in different addition levels) bulk MgB2 samples. All disk-shaped MgB2 bulk samples were manufactured using the conventional solid-state reaction method and the sintering process was implemented at 700 & DEG;C for 3 h in pure Ar atmosphere. Nano-Pt addition levels were 0.0; 0.5; 1.0; 3.0; 5.0; 7.0 wt% of MgB2 powders and nano-SiC addition level was 10 wt% of MgB2 powders. X-ray diffraction (XRD) analysis shows that Mg2Si, Pt3Si and Mg2PtSi impurity phases were detected in nano-Pt/nano-SiC co-added MgB2 samples. These impurity phases created zones acting as influential pinning centers for the flux lines. The critical current density (J(c)) indicated improvement at high field (B > 4 T) for 10 wt% nano-SiC added sample and all nano-Pt/nano-SiC co-added samples. The values of J(c) in 6 T field at 5 K were calculated to be 3.1 x 10(3) A/cm(2) for pristine MgB2 sample, 1.5 x 10(4) A/cm(2) for the 10 wt% nano-SiC added MgB2 sample and 1.6 x 10(4) A/cm(2) for the 1.0 wt% nano-Pt and 10 wt% nano-SiC co-added MgB2 sample. At applied magnetic fields higher than about 4 T at 5 K and 10 K, the best J(c) performance among all samples is given by 1.0 wt% nano-Pt and 10 wt% nano-SiC co-added MgB2 sample. The pristine MgB2 sample has a the critical temperatures (T-c) of 38.1 K and T-c has dropped with nano-Pt/nano-SiC co-added bulk MgB2 samples. The flux pinning mechanisms of both pristine and all nano-Pt/nano-SiC co-added bulk MgB2 samples were seen to be the normal point pinning in magnetic fields lower than B-max (the field at which the pinning force reaches its maximum) at 15 K.