Sintered powders and wires of superconducting MgB2 have been fabricated under a variety of conditions in order to determine details of the diffusion of the Mg into B and to study the types of defects that arise during growth. For samples prepared by exposure of boron to Mg vapor at 950∘C, the conversion of particles of less than 100μm size particles to MgB2 is complete in about 2h. The lattice parameters of the MgB2 phase determined from X-ray are independent of the starting stoichiometry and the time of reaction. Wire segments of MgB2 with very little porosity have been produced by reacting 141μm diameter boron fibers in an atmosphere of excess Mg vapor at 950∘C. Defects in the reacted fibers are predominantly the voids left as the boron is converted to MgB2.
@article{arxiv.cond-mat/0103390,
title = {Synthesis and Processing of $MgB_2$ powders and wires},
author = {C. E. Cunningham and C. Petrovic and G. Lapertot and S. L. Bud'ko and F. Laabs and W. Straszheim and D. K. Finnemore and P. C. Canfield},
journal= {arXiv preprint arXiv:cond-mat/0103390},
year = {2009}
}