Fabrication and growth mechanism of MgB2 nanowires during reactive sintering

A direct synthesis route from Mg and B powders to crystalline MgB2 nanowires was developed by reactive sintering: the sample was heated from room temperature to 994 K at a rate of 20 K/min and then cooled down at a rate of 40 K/min, according to the non-equilibrium conversion reaction theory. The prepared MgB2 nanowires exhibit a uniform diameter of 50 nm. Both SEM and SQUID studies on the obtained nanowires suggest it has a high quality and a critical transition temperature comparable with that of an ideal one. A presumable mechanism for the process in the formation MgB2 nanowires is also proposed, through which the formation of this special structure is considered to be connected with the preferable growth in several fixed crystal facets by assisting with liquid Mg melt.