Realize High Thermoelectric Properties in n-Type Bi₂Te₂.₇Se₀.₃/Y₂O₃ Nanocomposites by Constructing Heterointerfaces
2021
Hu, Qiujun | Qiu, Wenbin | Chen, Longqing | Chen, Jie | Yang, Lei | Tang, Jun
Due to the excellent thermoelectric performance, bismuth telluride (Bi₂Te₃) compounds are highly promising for the thermoelectric conversion in the room temperature range. However, the inferior thermoelectric performance of the n-type leg severely restricts the applications of Bi₂Te₃-based thermoelectric couples. Herein, n-type Bi₂Te₂.₇Se₀.₃ (BTS)-based thermoelectric materials incorporated with nanosized Y₂O₃ (0.5–3 wt %) are prepared and their thermoelectric properties are systematically studied. The dramatically improved thermoelectric performance is ascribed to the realization of a multiscale feature of Y₂O₃ nanoparticle (NP)-induced interfacial decorations distributed along grain boundaries, which creates massive BTS/Y₂O₃ interfaces for the manipulation of carrier and phonon transport properties. The geometric phase analysis is employed to further confirm the condition of local strain in the BTS composite incorporated with Y₂O₃ NPs. Due to the presence of heterointerfaces and high density of dislocations in BTS matrices, the minimum lattice thermal conductivity (κₗ) of the nanocomposites (NCs) is dramatically suppressed from 0.76 to 0.37 W m–¹ K–¹. With the incorporation of 3 wt % Y₂O₃ NPs, the Vickers hardness of the BTS/Y₂O₃ NC is increased by about 32%. Overall, the BTS + 1.5 wt % Y₂O₃ NC maintains excellent thermoelectric properties (ZTₐᵥₑ = 1.1) in the whole operative temperature range (300–500 K). The present strategy of implementing high-density heterogeneous interfaces by Y₂O₃ NP addition offers an applicable pathway for fabricating high-performance thermoelectric materials with both optimized thermoelectric properties and mechanical properties.
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