Possibility of the Higher Critical Temperature on MgB2 Superconductor Synthesized by Powder-In-Sealed-Tube Method

MgB 2 is a metal compound superconductor which has critical temperature value ~ 39 K. The critical temperature of MgB 2 superconducting wire is higher than Nb-based superconductor, NbTi and Nb 3 Sn. It is a promising superconductor to replace the Nb-based superconductor that has been applied as a widely used superconducting wire. The aim of this study is to synthesize MgB 2 superconductor with the various amount of Mg element using powder-in-sealed-tube method. Mg and B powders were mixed, grounded and poured into stainless steel SS304 tube. As-mixed powder was then heated at 800 C for 2 h in standard air ambient inside a sealed tube. After that, the crystal structures, surface morphology and resistivity versus temperature of all samples were characterized using X-ray diffraction (XRD), scanning electron microscopy and cryogenic system, respectively. Based on the result of XRD, the majority of MgB 2 phase was formed even though there were slightly small amount of B 2 O phases. The critical temperature ( T c ) onset of MgB 2 with the addition of 0, − 5, − 10, 5 and 10 wt% Mg was calculated 42.03; 42.25; 42; and 41.8 K, accordingly. These critical temperature values are relatively higher than other studies among this type of superconductors. And then, to study the grinding effect, one of the as-calcined pellets was ground and pressed to form bulk sample again. T C,onset and T C,zero of this sample were decreased 3 and 18 K, respectively.