The Annealing Effects of MgB_2 and Experimental Study on Thermostability of MgB_2

The effects of annealing on superconducting transition and the thermostability of MgB_2 have been investigated. MgB_2 is fabricated on boron flakes by annealing in the magnesium atmosphere at different temperatures and period of times. The temperature range from 700 to 1?000?℃ is appropriate to prepare MgB_2 in the experiments. At higher temperature shorter time is needed to get relatively high T_c. The thermostability experiments show that after the heat treatment in the atmosphere without Mg, MgB_2 is stable below 700?℃ and begins to decompose from 800?℃ until the complete loss of superconductivity. The lower temperature is needed to form MgB_2 phase when using Mg-B film precursor instead of boron flakes.