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Preparation and properties of Mg(B<sub>1-x</sub>C<sub>x</sub>)<sub>2</sub> using Carbon Chemical Vapor Coated Boron

By E.A. Young and Y. Yang

Abstract

Promising initial results on bulk Mg(B1-xCx)2 prepared with carbon doped boron are presented. Carbon doping is achieved by reaction of ethylene gas on boron powder using a stainless steel tube furnace, a technique suitable for industrial scale processing. The nominal amount of doping was controlled by varying the reaction time with a fixed volume of ethylene gas, and the actual carbon uptake was determined by weight change after the reaction.The amount of carbon substitution x in the Mg(B-xCx)2 was found using the angular shift in the (100) x-ray reflection. Carbon substitution by the full nominal content in the C doped precursor boron was obtained for doping up to 7.2at%, as shown by a -axis compression consistent with that of carbon doped single crystals. The critical current density of the 4 at% C doped sample for temperatures at 20–30 K and fields up to 4 T, relevant to high temperature applications, was significantly higher than those in the published literature. The C of a 10wt% nano-SiC doped sample, used as a comparative benchmark, was found to be lower than the C doped sample at field below 2 T, but to reduce slower at higher fields. Structure analysis of the SiC doped sample revealed a coexistence of two C substitution levels of 2.25%at and 5.25%at

Topics: QD, QC
Year: 2007
OAI identifier: oai:eprints.soton.ac.uk:66435
Provided by: e-Prints Soton

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Citations

  1. (2006). Control of nano carbonsubstitutionforenhancingthecriticalcurrentdensityinMgB2,” Supercond.
  2. (2005). Improved upper critical field in bulk-form magnesium diboride by mechanical alloying with carbon,”
  3. (2006). The reactive liquid Mg infiltration process to produce large superconducting bulk

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