Synthesis of MgB 2 from magnesium rich powders

Superconducting bulk MgB 2 samples have been synthesized by employing a modified heat treatment without using any additional process steps generally undertaken in view of the substantial loss of Mg during sintering owing to its high vapour pressure at the processing temperature. Starting with Mg rich powder mixtures having different atomic ratios of Mg:B (as against the nominally required 1:2 ratio), we have obtained superconducting MgB 2 samples showing a transition temperature (T c ) in the range 40.4-40.7K when synthesized at sintering temperatures in the range 720-900°C. Typically, a MgB 2 sample (T c = 40.5K) obtained from heat treating Mg and B in the ratio of 2:2 at 870°C for 1h duration exhibited critical current density in excess of 1×10 7 A/m 2 at =38K. Our results further show that MgO is not detrimental to superconductivity.