Crystal growth of MgB2

The problems in MgB2, crystal growth are discussed on the basis of the chemical and thermodynamic information about Mg-B system. After comparing and analyzing the reported crystal growth methods, a novel technique for reproducible crystal growth of MgB2, at a high pressure in Mg-B-N system is presented. The single crystals of sub-millimeter size were grown at P = 5 GPa, T = 1600-1700 degreesC with the temperature gradient of >200 degreesC/cm. For their formation the liquid-assisted solid-state re-crystallization mechanism was proposed. The variation of processing parameters allowed us to control the morphology and superconducting properties of growing crystals. The good quality of single crystals was confirmed by X-ray diffraction, magnetic and resistivity measurements and opened a route for various fundamental studies of MgB2. (C) 2002 Elsevier Science B.V. All rights reserved.