Multicrystalline Mg2Si crystals were grown using a Brigdman method combined with a die-casting growth technique. Although molten and/or vapor-phase Mg at elevated growth temperatures exhibit high chemical reactivity with the surrounding crucible materials, the use of an alumina crucible with a BN coating allowed single phase crystal growth and Mg2Si of good crystalline quality. Incorporation of carbon into the Mg2Si was observed to form Mg2Si_(1-x)C_x. For x=0.01 and 0.03, a lower thermal conductivity and higher figure of merit than those of Mg2Si were observed in the temperature range from room temperature to 773 K. The maximum figure of merit was 0.62 at 773 K for a Mg2Si_(0.99)C_(0.01) sample.
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