MgB 2 fabrication by diffusion-controlled three layered (B–Mg–B) technique

Abstract

MgB 2 was successfully fabricated through diffusion-controlled three-layered (B–Mg–B) technique under high pressure. Due to melting temperature of Mg, the material was pre-heat treated at 600 °C between 1 and 48 h. Optimum pre-heat treatment condition was found to be 600 °C for 48 h. Then, the compacted material was grinded and pelletized under pressure of 2 ton. The pellets were heat treated at 600–900 °C for 1–48 h. Optimum heat treatment condition was determined to be 800 °C for 1 h for formation of almost pure MgB 2. Diffusion coefficient was determined with Fick's law and EDX data. Diffusion coefficient value for B in Mg matrix and Mg in B matrix was determined to be 1.66×10 −7 and 3.14×10 −8 cm 2/sn, respectively. Best T c value (39.4 K) was obtained for material heat treated at 800 °C for 1 h. A symmetric hysteresis was obtained for the best MgB 2 material and magnetization decreased with increase in the temperature and the applied magnetic field.