The Phase Analysis of Spark Plasma Sintered MgB₂ After Ball Milling

Mg and amorphous B powders below 10 and 3 micro meter were used as raw materials, and mixed by planetary-mill for 9 hours at argon atmosphere. MgB₂ bulk was fabricated at the various temperatures by Spark Plasma Sintering. In the sintering process, mixed powders were sintered in graphite mold, at the pressure of 55 Mpa. The fabricated MgB₂ samples were evaluated with XRD, EDS, FE-SEM, PPMS. MgB₂, MgO and Fe phases were observed from XRD result. In the results, MgO and Fe were impurity which may affect superconducting properties of MgB₂ samples, and it's distribution could be confirmed from EDS mapping result. In order to confirm the formation of MgB₂ phase, DTA was used as heating rate of 10 °C/min at Ar atmosphere from room temperature to 1200 °C. In the PPMS result, the T _c (critical temperature) was about 21 K, and the density of spark plasma sintered samples increased to 1.87 g/cm³ by increasing sintering temperature.