Abstract:

The influence of the pressure on the magnetic and superconducting properties of polycrystalline MgB2 bulks was studied. Bulk MgB2 samples were prepared using conventional in-situ solid state reaction and hot-pressing methods. The structural and electromagnetic properties of MgB2 samples were studied by using x-ray diffraction (XRD), scanning electronic microscope (SEM), magnetic hysteresis (M-H) and magnetic levitation force (Fz, Fx) measurements. XRD measurements proved high quality of MgB2 bulks with only small traces of MgO impurity phase. The zero-field Jc value reached 240 kA/cm2 for MgB2 sample produced by hot-press while 23 kA/cm2 for MgB2 sample produced by conventional in-situ at measurement temperature of 25 K. The max. levitation force values were obtained as 11.60 N and 15.42 N for MgB2 bulk samples produced by in-situ and hot-press methods at 25 K, respectively. All these magnetic measurements result indicate that pressure acts like driving force for manufacturing highly dense and high levitation capability MgB2 bulk superconductors.

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