Thermoelectric properties of /spl beta/-FeSi/sub 2/ with oxide-particles doping

We investigated thermoelectric properties of Fe-Si systems (/spl alpha/, /spl epsiv/ and /spl beta/-phase) with oxide particles diffused in. The oxides used here were La/sub 2/O/sub 3/, Yb/sub 2/O/sub 3/, Ag/sub 2/O, NiO and Cr/sub 2/O/sub 3/. They were sintered by solid reaction method, then they were annealed for 3 hours. We found that the shorter annealing time was obtained by adding a small amount of oxides, lattice thermal conductivity decreased by addition of Yb/sub 2/O/sub 3/. Interfacial effects were found that carriers moved between the solidified Ag and the Fe-Si systems by addition of Ag/sub 2/O, and the barrier between the oxides and the Fe-Si systems was observed by addition of La/sub 2/O/sub 3/ and Yb/sub 2/O/sub 3/. Figure of merit was the following in Fe/sub 0.92/Mn/sub 0.08/Si/sub 2/ after 3 hours annealing; Z=1.85/spl times/10/sup -4/ (K/sup -1/) for 3 wt% Yb/sub 2/O/sub 3/, Z=0.75/spl times/10 /sup 4/(K/sup -1/) for 3, 5 and 10 wt% Ag/sub 2/O and the unadded.