Enhancing Thermoelectric Performance of n-Type Bi₂Te_2.7Se_0.3 through Incorporation of Amorphous Si₃N₄ Nanoparticles

Bi₂Te₃-based thermoelectric (TE) materials are the state-of-the-art compounds for commercial applications near room temperature. Nevertheless, the application of the n-type Bi₂Te_2.7Se_0.3 (BTS) is restricted by the comparatively low figure of merit (ZT) and intrinsic embrittlement. Here, we show that through dispersion of amorphous Si₃N₄ (a-Si₃N₄) nanoparticles both 14% increase in power factor (at 300 K) and 48% decrease in lattice thermal conductivity are simultaneously realized. The increased power factor comes from enhanced thermopower and reduced electrical resistivity while the reduced lattice thermal conductivity originates mainly from scattering of middle- and low-frequency phonons at the incorporated a-Si₃N₄ nanoparticles. As a result, a large ZT_max = 1.19 (at 373 K) and an average ZT_ave ∼ 1.12 (300-473 K) with better mechanical properties are achieved for the BTS/0.25 wt % Si₃N₄ sample. Present results demonstrate that the incorporation of a-Si₃N₄ is a promising way to improve TE performance.