Single crystal growth of MgB2 and thermodynamics of Mg-B-N system at high pressure

Single crystals of MgB2 have been grown at high pressure via the peritectic decomposition of MgNB9. The crystals are of a size up to 1.5 x 0.9 x 0.2 mm(3) with a weight up to 230 mug, and typically have transition temperatures between 37 and 39 K with a width of 0.3-0.5 K. Investigations of the P-T phase diagram prove that the MgB2 phase is stable at least up to 2190 degreesC at high hydrostatic pressure in the presence of Mg vapor under high pressure. Small variations of T, are caused by doping with metal elements from the precursor or annealing of defects during the crystal growth process. (C) 2002 Elsevier Science B.V. All rights reserved.