Carbon doping of MgB sub(2 by toluene and malic-acid-in-toluene)

The decomposition of malic acid (C sub(4H) sub(6)O sub(5) in the presence of Mg and B was studied using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) which revealed that malic acid reacted with Mg but not B. Also, the addition of toluene (C) sub(7)H sub(8) to dissolve malic acid followed by subsequent drying resulted in no reaction with Mg, indicating that the malic acid had decomposed during the dissolution/drying stage. The total carbon contributed by toluene versus a toluene/5 wt.% malic acid mixture was measured using a LECO CS600 carbon analyzer. The toluene sample contained [inline image]0.4 wt.% C while the toluene/malic acid mixture had [inline image]1.5 wt.% C, demonstrating that the toluene contributed a significant amount of carbon to the final product. Resistivity measurements on powder-in-tube MgB) sub(2) monofilamentary wires established that the toluene/malic acid doped sample had the highest B sub(c) sub(2). However, the toluene-only sample had the highest transport J sub(c over most of the magnetic field range (0-9 T), equaled only by that of toluene/malic-acid sample in fields above 9 T.)