Thermoelectric Performance Enhancement in BiSbTe Alloy by Microstructure Modulation via Cyclic Spark Plasma Sintering with Liquid Phase. (8th February 2021) - Zhuang, Hua‐Lu
Abstract: The widespread application of thermoelectric (TE) technology demands high‐performance materials, which has stimulated unceasing efforts devoted to the performance enhancement of Bi2 Te3 ‐based commercialized thermoelectric materials. This study highlights the importance of the synthesis process for high‐performance achievement and demonstrates that the enhancement of the thermoelectric performance of (Bi, Sb)2 Te3 can be achieved by applying cyclic spark plasma sintering to Bi x Sb2– x Te3 ‐Te above its eutectic temperature. This facile process results in a unique microstructure characterized by the growth of grains and plentiful nanostructures. The enlarged grains lead to high charge carrier mobility that boosts the power factor. The abundant dislocations originating from the plastic deformation during cyclic liquid phase sintering and the pinning effect by the Sb‐rich nano‐precipitates result in low lattice thermal conductivity. Therefore, a high ZT value of over 1.46 is achieved, which is 50% higher than conventionally spark‐plasma‐sintered (Bi, Sb)2 Te3 . The proposed cyclic spark plasma liquid phase sintering process for TE performance enhancement is validated by the representative (Bi, Sb)2 Te3 thermoelectric alloy and is applicable for other telluride‐based materials. Abstract : The thermoelectric power factor and figure of merit of the BiSbTe alloy are significantly improved by cyclic liquid‐phase aided spark plasma sintering process. The present proposed fabrication process modulates the microstructure in a wide range of scale from nano‐sized dislocations to micrometer grain size, leading to a synergistic control of charge carriers and phonon transport.