Synthesis of bulk beta-FeSi2 crystal

Abstract

The feasibility of adopting two methods to synthesizing the bulk crystal of beta-FeSi2, was examined: one involving two-step Bridgmann growth with a three-zone furnace and another invoking melting growth with a single zone furnace, As-grown iron disilicides were annealed in the furnaces at different temperatures for various durations, Experimental result,; indicate that a larger beta-FeSi, crystal can be obtained using the two-step fast Bridgmann growth method kith post-annealing at 1073 K for 300h. Fast cooling and adding some copper impurities to the raw materials were found to promote the growth of beta-FeSi2. The iron disilicide crystal. with a large contribution from the 8 phase, supported a higher thermoelectric power. A thermoelectric power of 450 muV/K was obtained at 300-900 K for the sample with copper doping The energy hand gap of beta-FeSi2 samples was about 0.82-0.88 eV. determined by measuring the temperature-dependent resistivity.