Thermoelectric and mechanical properties of multi-walled carbon nanotube doped Bi0.4Sb1.6Te3 thermoelectric material

Abstract

Since many thermoelectrics are brittle in nature with low mechanical strength, improving their mechanical properties is important to fabricate devices such as thermoelectric power generators and coolers. In this work, multiwalled carbon nanotubes (CNTs) were incorporated into polycrystalline Bi0.4Sb1.6Te3 through powder processing, which increased the flexural strength from 32 MPa to 90 MPa. Electrical and thermal conductivities were both reduced in the CNT containing materials, leading to unchanged figure of merit. Dynamic Young's and shear moduli of the composites were lower than the base material, while the Poisson's ratio was not affected by CNT doping.

Spark plasma sintered bismuth telluride-based thermoelectric materials incorporating dispersed boron carbide

“…The trends are broadly in agreement with the literature on p-type bismuth telluride based materials produced using SPS and reinforced with nano-scale phases [7,12,14,16,[20][21][22][23]. The data in Figure 4 show generally lower Seebeck coefficient and electrical resistivity than some of the reports in the literature, but the overall performance, indicated by the zT values in Figure 5, are similar.…”

“…66 [23] 90 [12] More typically 1.1 (∥) and 0.8 (⊥) [7,9] Best room temperature values of up to 1.1 (⊥) and 0.8 (∥) quoted [7], typical value 0.9 (⊥) [16,19]. Note: max zT occurs ⊥ , the opposite of directionally solidified material…”

“…Mechanical property improvement has been the justification for the development of polycrystalline materials produced by a variety of processes including hot-pressing [11,12], extrusion [8,13], plasma activated sintering [14,15] and spark plasma sintering (SPS) [7,[16][17][18][19][20][21][22][23][24]. The addition of nanoscale particulate reinforcements (SiC [17,18,23], C 60 [7], multi-wall carbon nanotubes [12] and Al 2 O 3 [22]) have been pursued. The intention is to maintain thermoelectric performance in polycrystalline materials while improving their mechanical properties.…”

On the effect of carbon nanotubes on the thermoelectric properties of n-Bi 2 Te 2.4 Se 0.6 made by mechanical alloying

“…However, while the nano-domains formed using specific synthetic techniques are of the same stoichiometry that the matrix, the addition of foreign nano objects necessitates considering their possible reactivity with the matrix. Hence, it is rather species considered inert that have been considered, such as alumina, silica, fullerenes or carbon nanotube (CNT) [18][19][20][21][22][23][24][25][26].…”

Thermoelectric Properties of Alumina-Doped Bi0.4Sb1.6Te3 Nanocomposites Prepared through Mechanical Alloying and Vacuum Hot Pressing

“…Several studies have reported the preparation of nanocomposite Bi0.4Sb1.6Te3 bulk samples [15][16][17][22][23][24][25][26] through BM and hot pressing or spark plasma sintering (SPS). TE properties and preparation methods are listed in Table 1.…”