Realizing Excellent Thermoelectric Performance of Sb₂Te₃ Based Segmented Leg with a Wide Temperature Range Using One‐Step Sintering

Abstract

To achieve a wide temperature range and a high figure‐of‐merit, segmented assembling is considered as the most effective method based on optimized low‐temperature and medium‐temperature thermoelectric materials. In this work, divalent magnesium (Mg) as acceptor doping in both Bi0.5Sb1.5Te3 and indium (In) alloyed Sb2Te3 play an important role in improving thermoelectric performance, including enhanced power factor by balancing the electrical conductivity and Seebeck coefficient, reduced bipolar thermal conductivity by delaying occurrence of intrinsic excitation, and reduced lattice thermal conductivity due to point defects. Finally, both the figure‐of‐merit (ZT) value and the corresponding operating temperature range are improved. Typically, Mg0.01Bi0.5Sb1.49Te3 with a ZTave of 1.16 from 300 to 520 K and a ZTave of 0.84 for Mg0.02In0.1Sb1.88Te3 from 500 to 680 K are obtained. To further obtain wide‐temperature high ZT value, p‐type Mg0.01Bi0.5Sb1.49Te3/Mg0.02In0.1Sb1.88Te3 segmented leg with excellent interface bonding and extremely low contact resistivity is successfully fabricated by only one‐step sintering process. The corresponding average ZT value is up to 1.02 with a broad temperature range from 300 to 680 K, and a maximum theoretical conversion efficiency of 12.7% with a temperature difference of 380 K is obtained. This provides guidelines for high efficiency thermoelectric devices.

Tuning Optimum Temperature Range of Bi2Te3‐Based Thermoelectric Materials by Defect Engineering

“…Recently, using the same strategy as Hu et al. but switching the dopants to the Mn and Mg, similar results were obtained by Qin et al . The bipolar thermal conductivity κ b and zT as a function of temperature are shown in Figure (c) and (d).…”

“… Temperature dependence of zT for (a) (Bi,Sb) 2 Te 3.2 , (Bi,Sb) 2 Te 3 , (b) Bi 0.3 In x Sb 1.7‐ x Te 3 and In x Ag y Sb 2‐ x Te 3 polycrystals . (c) Bipolar thermal conductivity κ b and (d) zT as a function of temperature for Mn x Bi 0.5 Sb 1.5‐ x Te 3 , Mn x In 0.15 Sb 1.85‐ x Te 3 and Mg 0.025 In 0.1 Sb 1.875 Te 3 polycrystals …”

Cu2Te Incorporation-Induced High Average Thermoelectric Performance in p-Type Bi2Te3 Alloys

“…The temperature associated with the peak zT moves toward a higher region as the Cu 2 Te content increases, which is attributed to delayed intrinsic transition and the suppression of bipolar conduction. The average figure of merit ( zT ave ) is successfully achieved at ∼1.12 in the temperature range of 350–500 K (Figure b), compared to many other superior Bi 2 Te 3 -based alloys. ,,− To further interpret the overall performance of BST-Cu 2 Te samples over their operating temperature range, the engineering figure of merit ( zT eng ), a more reliable parameter than zT ave , was calculated (see details in the Supporting Information) . As expected, the zT eng value significantly improves at diverse temperature differences (Δ Τ ) with a cold-junction T c of 350 K (Figure S4).…”

Optimized Thermoelectric Properties of Bi0.48Sb1.52Te3 through AgCuTe Doping for Low-Grade Heat Harvesting

“…It is, thus, essential to regulate the hole concentration for sintered materials of p-type Bi 0.5 Sb 1.5 Te 3 or similar compositions. Usually, the nonequivalent element doping, such as Ag, Cu, Mn, Mg, Pb, Cd, Zn, or Ca, can effectively increase the hole concentration. ,,− Moreover, doping with the chalcogenides of these elements can also introduce various defects into the Bi 2 Te 3 -based matrix and reduce κ lat for higher TE performance. Especially, (Cu, Ag) 2 X (X = S, Se, and Te) are typical “phonon-liquid electron-crystal” materials, which have attracted wide attention due to their extremely low κ lat . , Actually, Cu 2 Se doping in Bi 2 Te 3 and Cu 2 Te doping in SnTe have been proved to effectively reduce κ lat . , …”