LAUSR

Si exhibits high power factor, but its lattice thermal conductivity (κlat) is significantly high, leading to a low thermoelectric figure of merit (ZT) to be around 0.01. Here, we attempted to reduce the κlat of Si with keeping high power factor by dispersing NiSi2 precipitates. Since the lattice parameter of NiSi2 (0.5416 nm) is nearly equal to that of Si (0.5430 nm), it is expected to form coherent interfaces between Si and NiSi2, which would have less effect on the carrier transport to maintain high power factor. The Si/NiSi2 bulk composites with the starting composition of (Si100P3)98Ni2 were synthesized by a combined method of melt spinning and spark plasma sintering. The κlat of the samples clearly decreased while the carrier mobility did not change significantly, leading to the improved ZT value of 0.23 at 1033 K, approximately ∼50% higher than that of a typical n-type bulk Si.