High thermoelectric figure-of-merit in p-type nanostructured (Bi,Sb)2Te3 fabricated via hydrothermal synthesis and evacuated-and-encapsulated sintering

Abstract

High ZT values of nanostructured Bi 2Àx Sb x Te 3 for energy conversion are fabricated by hydrothermal methods followed by cold-pressing and sintering in an evacuated and encapsulated ampoule. We show that the sample with a nominal composition of x ¼ 1.55 exhibits a dimensionless figure of merit ZT ¼ 1.65 at 290 K and 1.75 at 270 K with significant 60-70% improvement of that of the commercial stateof-the-art Bi 2 Te 3 materials around room temperature. The significant ZT improvement arises from the much-reduced thermal conductivity. The low thermal conductivity is mainly due to the increased phonon scattering in the nanostructured materials.

Thermoelectric properties of Ca3−xEuxCo4O9+δ (0≤x≤0.1)

“…The product of the thermoelectric coefficient and temperature can therefore be understood as the mean energy flow carried by a conduction electron. Using the condition of ∂f(ε)/∂ε ¼δ (ε ÀE F ), and s¼ neμ(ε) [13][14][15][16][17][18][19][20][21][22] Eq. (2) can be written as…”

“…The encapsulated sensor was sandwiched between two pieces of samples. During a preset time, 200 resistance recordings were taken, and from these a relation between temperature and time was established [16]. The oxygen content and valence state of cobalt were determined using iodometric titration [17].…”

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

“…There are a number of representative methods presented in the literature, ranging from hydrothermal synthesis followed by hot-pressing (HT-HP) [52,53], [63], ball-milling followed by hot-pressing (BM-HP) [54,55,64,65], microwave synthesis followed by cold pressing and sintering [66], in situ strain-induced thermal forging technique [67,68], to melt spinning followed by spark-plasma sintering (MS-SPS) [56-60, 62, 69-72]. The best ZT values of p-type (Bi,Sb) 2 Te 3 nanocomposites reached 1.4-1.5 by using BM-HP [54,55] or MS-SPS techniques [56][57][58].…”

Significantly enhanced thermoelectric performance of Cu-doped p-type Bi0.5Sb1.5Te3 by a hydrothermal synthesis method

“…17,[28][29][30][31] Instead, hydrothermal synthesis as an effective method to fabricate Bi 2 Te 3 -based materials takes much shorter time, 32,33 while the synthesis of a single-phase Bi 0.5 Sb 1.5 Te 3 solid solution by hydrothermal reaction is rarely reported. 18,34,35 Furthermore, the reported room-temperature thermoelectric properties of the Bi 2 Te 3 -based alloy synthesized by the hydrothermal method are not as good as expected. 18,35,37 Therefore, it is desirable to develop a facile hydrothermal method to prepare an ideal single-phase Bi 0.5 Sb 1.5 Te 3 alloy with optimized thermoelectric properties.…”

“…The Bi 2 Te 3 compound has a rhombohedra structure 32 with the space group R 3m, wherein along the c-axis, the atomic layers array in the order of -Te(1)-Bi-Te(2)-Bi-Te(1)-and the neighboring Te(1) layers are linked by weak van der Waals bonds. [34][35][36][37] Therefore, the morphology of Bi 2 Te 3 -based alloy normally exhibits the feature of hexagonal platelets. For the powders obtained in our work, under the control of hydrothermal synthesis, most of grains are nanoparticles with decient crystallinity, while only a small number of grains are well-crystallized, existing as hexagonal platelets.…”