Preparation and characterization of magnesium diboride superconductor by melting process (original) (raw)
2003, Korean Journal of Chemical Engineering
The recent discovery of the binary metallic magnesium diboride (MgB 2 ) superconductor having a remarkably high transition temperature (T c ) of 39 K has generated excitement among the scientist worldwide and gained great scientific interest. Various methods (viz. PLD, solid state reaction etc.) are reported for the preparation of this material in different forms (bulk, wire, thin film) which require a high processing temperature (750 to 950 o C). In this paper, we report a new method of processing MgB 2 superconductor that meets all the properties when compared with other processes. In this work, polycrystalline MgB 2 was prepared by using melting process at low temperature (660 o C). The stoichiometric mixture of Mg-rich and B-rich was pressed into pellets and piled to form Mg-rich/B-rich/Mg-rich system. The piled specimen was then heated up to 800 o C for four hrs with a heating rate of 5 o C/min. The sample was then kept at 660 o C for 12 hrs after cooling from 800 to 660 o C in 30 min. For comparison, the sample was also sintered at 660 o C for 24 hrs. The samples were characterized by using XRD, EDX, SEM, four probe AC methods and magnetization measurements using SQUID magnetometer. The critical temperature was found to be 39 K which shifts towards lower temperature with increasing applied field (0 to 9T). The critical current density, according to Bean's critical state model was estimated and found to be ~10 5 A/cm 2 , which is comparable to the reported data.
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