Highly pure, dense SiB4 and SiB6 plates were prepared by chemical vapor deposition (CVD) at deposition temperatures (Tdep) from 1323 to 1773 K, total gas pressures (Ptot) from 4 to 40 kPa and B/Si source gas ratios (mB/Si=2B2H6/SiCI4) from 0.2 to 2.8, and their thermoelectrical properties were measured. The Seebeck coefficient (S) of CVD-SiB6 (0.7 mm in thickness), which is known to be a high temperature thermoelectric material, was 320 μVK1, while its electrical conductivity (s) was 7 Q-1cm-1, SiB6 + TiB2 and SiB6 + SiB4in situ composite plates were also prepared to improve the thermoelectric property of CVD-SiB6. The σ value of the CVD-SiB6 + 12 wt% TiB2in situ composite plate (0.7 mm in thickness) was one order of magnitude larger than that of CVD-SiB6 at room temperature, while the figure of merit for the thermoelectric materials (Z) was smaller because of the smaller value of S. However, the Z value of SiB6 + 40 wt% SiB4in situ composite plate (0.5 mm in thickness) was 10-5, larger than that of CVD-SiB6.
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
- Industrial and Manufacturing Engineering