Phase formation of superconducting MgB2 at ambient pressure

MgB2 superconductor has been synthesized using a simple technique at ambient pressure. The synthesis was carried out in helium atmosphere over a wide range of temperatures. Magnesium was employed in excess to the stoichiometry to prevent the decomposition of MgB 2. Samples of MgB 2 thus prepared have been almost free from MgO as compared to other methods. Resistivities of the samples are quite low with r esi- dual resistivity ratio (RRR) of around 3. Tc(R = 0) is 38·2-38·5 K with Δ ΔTc of 0·6-1·0 K. Comparative studies of various methods of low pressure synthesis have been presented.