Large upper critical field and irreversibility field in MgB2 wires with SiC additions -: art. no. 092507

Resistive transition measurements are reported for MgB2 strands with SiC dopants. The starting Mg powders were 325 mesh 99.9% pure, and the B powders were amorphous, 99.9% pure, and at a typical size of 1-2 mu m. The SiC was added as 10 mol % of SiC to 90 mol % of binary MgB2 [(MgB2)0.9(SiC)0.1]. Three different SiC powders were used; the average particle sizes were 200 nm, 30 nm, and 15 nm. The strands were heat treated for times ranging from 5 to 30 min at temperatures from 675 degrees C to 900 degrees C. Strands with 200 nm size SiC additions had mu(o)H(irr) and B-c2 which maximized at 25.4 T and 29.7 T after heating at 800 degrees C for 30 min. The highest values were seen for a strand with 15 nm SiC heated at 725 degrees C for 30 min which had a mu(o)H(irr) of 29 T and a B-c2 higher than 33 T. (C) 2005 American Institute of Physics.