Anisotropic n-Type Bi₂Te₃–In₂Te₃ Thermoelectric Material Produced by Seeding Zone Melting and Solid State Transformation

Abstract

Seeding zone melting is applied to produce bulk Bi 1.625 In 0.375 Te 3 with 7.5 atom % In in solid solution. The concentration distribution is markedly homogeneous and exhibits pronounced anisotropic electrical and thermal conductivity. Subsequent precipitation from the solid solution leads to the formation of a highly anisotropic composite thermoelectric material consisting of aligned microscaled Bi 2 Te 3 and extended micro-to nanoscaled In 2 Te 3 plates. By the precipitation, an increase of zT by a factor of 6 compared with the parent supersaturated solid solution crystal is achieved. This is attributed to the combination of a decrease of In concentration from 7.5 to 3 atom % in the Bi 2 Te 3 layer and an increasing interface density due to the precipitation of In 2 Te 3 . The Bi 2 Te 3 /In 2 Te 3 interface is determined as coherent, and the crystallographic orientation between the two phases is determined as ⟨2̅ 11⟩ In2Te3 //⟨11̅ 00⟩ Bi2Te3 , {111} In2Te3 //{0001} Bi2Te3 .

Ultralow Thermal Conductivity in Dual‐Doped n‐Type Bi2Te3 Material for Enhanced Thermoelectric Properties

“…More importantly, indium substitution in bismuth (Bi 2− x In x Te 3 for x = 0.375) reported by Liu et al. [ 39 ] still retained the hexagonal structure of the Bi 2 Te 3 system. Similarly, lutetium and selenium dual substitution in Lu x Bi 2− x Te 2.7 Se 0.3 reported by Cao et al.…”

“…(within the detection of the XRD instrument) but degraded the crystallinity of the samples. More importantly, indium substitution in bismuth (Bi 2−x In x Te 3 for x = 0.375) reported by Liu et al [39] still retained the hexagonal structure of the Bi 2 Te 3 system. Similarly, lutetium and selenium dual substitution in Lu x Bi 2−x Te 2.7 Se 0.3 reported by Cao et al [40] for 0 ≤ x ≤ 0.3 showed no evolution of extra XRD peaks.…”

Dependence of Solidification for Bi2Te3−xSex Alloys on Their Liquid States

“…In addition, these alloys also exhibit outstanding properties as phase change materials 5 and topological insulators 6 . The commercial Bi 2 Te 3 -based TE legs are generally prepared by unidirectional solidification methods, such as zone melting 7 , Bridgman 8 , and Czochralski 9 . Peak TE figure of merit values of these melt-grown ingots are typically in the range of 0.8 to 1.1 along the preferentially oriented ab-plane 4, 10 .…”

Anisotropic layered Bi2Te3-In2Te3 composites: control of interface density for tuning of thermoelectric properties

“…62,63) using the Perdew-Burke-Ernzerhof64 exchange-correlation functional for a supercell built to reproduce the coherent BT/IT interface also predicted the possibility of a metal-like interface state. A crystallographic orientation between Bi 2 Te 3 and In 2 Te 3 of and 65 and an adjusted band off-set as in Fig. 8 were used.…”