Formation of polycrystalline MgB₂ synthesized by powder in sealed tube method with different initial boron phase

Magnesium diboride, MgB₂ is a new high critical temperature superconductor that discovered in the beginning of the 21^st century. The MgB₂ has a simple crystal structure and a high critical temperature, which can be manufactured in several forms like thin films, tapes, wires including bulk in the large scale. For that reason, the MgB₂ has good prospects for various applications in the field of electronic devices. In the current work, we have explored the synthesis of MgB₂ polycrystalline using powder in a sealed tube method. Different initial boron phase for the synthesized of MgB₂ polycrystalline were used. These were, in addition to magnesium powders, crystalline boron, amorphous boron and combination both of them were respectively fitted in the synthesis. The raw materials were mixed in a stoichiometric ratio of Mg: B=1:2, ground using agate mortar, packed into stainless steel SS304. The pack was then sintered at temperature of 800°C for 2 hours in air atmosphere. Phase formation of MgB₂ polycrystalline in difference of initial boron phase was characterized using XRD and SEM. Referring to the diffraction pattern and microstructure observation, MgB₂ polycrystalline was formed, and the formation was effective when using the crystalline Mg and fully amorphous B as the raw materials. The critical temperature of the specimen was evaluated by the cryogenic magnet. The transition temperature of the MgB₂ specimen synthesized using crystalline magnesium and full amorphous boron is 42.678 K (ΔTc = 0.877 K).