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

Abstract

Bi 2 Te 3 -based thermoelectric (TE) materials are the state-of-the-art compounds for commercial applications near room temperature. Nevertheless, the application of the n-type Bi 2 Te 2.7 Se 0.3 (BTS) is restricted by the comparatively low figure of merit (ZT) and intrinsic embrittlement. Here, we show that through dispersion of amorphous Si 3 N 4 (a-Si 3 N 4 ) 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-Si 3 N 4 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 % Si 3 N 4 sample. Present results demonstrate that the incorporation of a-Si 3 N 4 is a promising way to improve TE performance.

Atomic-Resolution Interfacial Reaction Mechanism between Bi2Te3-Based Alloys and Ni Electrodes

“…Thermoelectric (TE) materials are important energy materials that can realize direct conversion between thermal energy and electrical energy. − Practically, p-type TE materials and n-type TE materials are assembled to build TE devices that generate electricity under a thermal gradient and provide heating or cooling under an electrical field. − For TE devices, it is important to find compatible electrode materials with low electrical resistivity, high thermal stability, and excellent connectivity with TE materials. − As TE devices are constantly under thermal gradient and electrical field, the microstructural evolution at the electrode/TE interface plays an important role in the TE device service performance. − Interdiffusion between the electrode and the TE material can degrade the TEM performance by forming new interfacial phases, breaking TE structural integrity, reducing interfacial electrical conductivity, causing mechanical failure, and so on. Therefore, it is critical to understand the interface structure evolution at atomic resolution under prolonged thermal annealing or electrical field, to design better TE/electrode interface …”