High performance Bi2Te3 nanocomposites prepared by single-element-melt-spinning spark-plasma sintering

Abstract

The last decade has witnessed nanocomposites becoming a new paradigm in the field of thermoelectric (TE) research. At its core is to prepare high performance TE nanocomposites, both p-and n-type, in a time and energy efficient way. To this end, we in this article summarize our recent effort and results on both p-and n-type Bi 2 Te 3 -based nanocomposites prepared by a unique single-element-meltspinning spark-plasma sintering procedure. The results of transport measurements, scanning and transmission electronic microscopy, and small angle neutron scattering have proved essential in order to establish the correlation between the nanostructures and the TE performance of the materials. Interestingly, we find that in situ formed nanocrystals with coherent boundaries are the key nanostructures responsible for the significantly improved TE performance of p-type Bi 2 Te 3 nanocomposites whereas similar nanostructures turn out to be less effective for n-type Bi 2 Te 3 nanocomposites. We also discuss the alternative strategies to further improve the TE performance of n-type Bi 2 Te 3 materials via nanostructuring processes.

Structural and Electrical Properties Characterization of Sb1.52Bi0.48Te3.0 Melt-Spun Ribbons

“…In this analyzed section, neither an amorphous, nor a nano-sized zone could be observed. This observation contrasts with the results obtained by Xie et al [39,42], who found the presence of an amorphous layer of about 500 nm in thickness for an overall thickness of about 3 mm (assuming that the authors showed the entire cross-section). The presence of nanoparticles embedded in an amorphous matrix (thickness of about 1 mm as shown in [39]) could not be observed either.…”

“…This technique has also been the subject of studies from a mathematical point of view [36]. Recently, this technique combined with subsequent hot pressing was employed successfully by several groups to achieve high thermoelectric performance with peak ZT values of 1.5 around 300 K in p-type Bi x Sb 2−x Te 3 for 0.48 ≤ x ≤ 0.52 [37][38][39][40][41][42][43]. Because melt-spun ribbons are subsequently consolidated to obtain bulk dense specimens, a detailed investigation of their microstructure-properties relationships is essential to better understand the influence of the MS process on the thermoelectric properties of Bi 2 Te 3 -based materials.…”

Bismuth Telluride and Its Alloys as Materials for Thermoelectric Generation

“…The importance of the structure of the powders in any sintering process is apparent from the work of Wu et al [49]. The best results were achieved using flower-like nanosheets yielding ZT of the order of unity over the whole temperature range 300 K to 525 K. Somewhat higher values of ZT were obtained by Xie et al [50] who combined melt spinning and spark plasma sintering. A ZT value of 1.5 at 400 K was found for p-type Bi 0.5 Sb 1.5 Te 3 but when the same techniques were applied to n-type Bi 2 (Te 1− y Se y ) 3 they yielded a ZT value of only 1.0.…”

Electrical and thermal transport properties of spark plasma sintered n-type Bi2Te3−xSex alloys: the combined effect of point defect and Se content

“…Li et al 9 reported a ZT of 1.33 at 373 K for the Bi 0.3 Sb 1.7 Te 3 alloy by adding SiC nano-dispersions using SPS. SPS combined with mechanical alloying (MA) is increasingly used for fabricating high-performance thermoelectric materials [14][15][16] also with improved mechanical properties, but it was also found to be ineffective for n-type conventional Bi 2 Te 2.7 Se 0.3 materials, because the reduction of thermal conductivity is insufficient to compensate for the deterioration of electrical performance. However, most excellent research studies about Bi 2 Te 3 -based compounds are focused on p-type materials but lower ZT values have been reported for powder-processed n-type Bi 2 Te 3based materials, when compared to their ingot counterparts.…”