Single crystal growth of MgB 2 by using Mg-self-flux method at ambient pressure

Abstract

Single crystals of magnesium diboride (MgB 2) have been grown at ambient pressure by using Mg-self-flux method. We chose the marketed MgB 2 powder as the raw material and Mg as the flux. The temperature was raised from room temperature to 1035°C for 4 h and maintained so for 2 h and then cooled down to room temperature slowly and then the single crystals of MgB 2 with hexagonal shape and a superconducting transition at about 37 K were obtained. The X-ray powder diffraction confirmed the MgB 2 phase, scanning electron microscope observed the single crystal images and electron diffraction patterns by using high-resolution transmission electron microscope confirmed the structure of MgB 2 single crystal. A new mechanism of liquid-assisted solid-state re-crystallization for growth of MgB 2 single crystal is proposed.