Titanium additions to MgB2 conductors

A series of doping experiments are reported for MgB2 conductors that have been synthesized using doped boron fibers prepared by chemical vapor deposition (CVD) methods. Undoped MgB2 samples prepared from CVD prepared fibers consistently give critical current densities, J(c), in the range of 500,000 A/cm(2) in low field at 5 K. These values fall by a factor of about 100 as the magnetic field increases to 3 T. For heavily Ti-doped boron fibers where the B/Ti ratio is comparable to 1, there is a substantial suppression of both T-c, superconducting volume fraction, and J(c) values. If, however, a sample with a few percent Ti in B is deposited on a carbon substrate and reacted at 1100 degreesC, then T-c is suppressed only a couple of degrees and critical current densities are found to be J(c) similar to 2-5 x 10(6) A/cm(2) for superconducting layers ranging from 4 to 10 mum thick. These materials show J(c) values over 10,000 A/cm(2) at 25 K and 1.3 T. (C) 2003 Elsevier Science B.V. All rights reserved.