The role of sintering conditions on the superconducting parameters of MgB 2

In this paper, we report the performance of MgB 2 superconductor prepared in a wide range of sintering temperatures. Pristine MgB 2 superconductor was prepared under the same conditions in one batch. The sintering temperatures are optimized to get the best superconducting parameters enhancing, especially critical current density. It was found that a low sintering temperature enhanced critical current density at the high magnetic region. Approximately the opposite of this effect was found in case of high sintering temperature. Crystallites size was increased with increasing of sintering temperature. It was found that smaller the crystallite size, higher was the value of critical current density. In addition, a slight increase in transition temperature was also observed as the sintering temperature was increased. High upper critical field values obtained at low sintering temperature were attributed to the strong grain boundary defects.