Synchronized enhancement of thermoelectric properties of higher manganese silicide by introducing Fe and Co nanoparticles

Introduction of nanophases is known to be effective in improving thermoelectric performance as it allows the simultaneous engineering of electronic and thermal transports. In this study, we synthesized Fe and Co nanoparticle-embedded MnSi_1.787Al_0.01 nanocomposites through a simple nanometal-decoration technique and spark plasma sintering. The nanoparticles introduced in the matrix caused energy band bending at the matrix–nanoparticle interface, which induced charge transfer and energy filtering effects. These two seemingly opposing effects were combined so as to increase the power factor of the nanocomposites by enhancing the electronic transport. Moreover, we found that the lattice thermal conductivity decreased owing to intensified phonon scattering. Hence, a maximum ZT of 0.53 (at 773 K) was achieved in 0.6 vol% Fe nanoparticle-embedded nanocomposites, which is 25% higher than that of the pristine sample.