Simultaneously Improved Thermoelectric and Mechanical Properties Driven by MgB₂ Doping in Bi_0.4Sb_1.6Te₃ Based Alloys

Abstract

Bi2Te3‐based alloys are the most mature and widely used thermoelectric materials since their zT value has been significantly improved in past decades. However, the poor mechanical strength and machinability derived from the easy cleavage along basal planes not only produce many scraps in the device fabrication process but also lead the devices unstable in the actual service. In this work, a tiny amount of MgB2 is induced in the Bi0.4Sb1.6Te3 alloy to simultaneously enhance the thermoelectric and mechanical properties. In detail, magnesium atoms occupy the bismuth/antimony sites to optimize the carrier concentration and suppress the bipolar effect, pushing the average zT value up to 1.16 ranging from 300 to 500 K, which catches up with the current highest level in p‐type Bi2Te3‐based materials. Moreover, the precipitation phase, boron nanoparticles, distributed at the grain boundaries can effectively improve the compressive strength from 166 to 239 MPa. The prominent thermoelectric and mechanical properties endow the materials with great potential for commercial applications.

Gibbs Adsorption and Zener Pinning Enable Mechanically Robust High‐Performance Bi2Te3‐Based Thermoelectric Devices

“…Our work suggests that introducing Zener pinning effects for grain refinement can be a general method to enhance mechanical properties, which should also be applied in other B or MgB 2doped GeTe [46,72] and Bi 2 Te 3 . [47][48][49]54] Moreover, the enhanced mechanical strength of Bi 2 Te 3 -based alloys by introducing SiC, [23,73] MoS 2 , [65] and TiC [68] nanodispersions should also be ascribed to the Zener pinning effects.…”

“…Bulk ultrafine‐grain Fe–22Mn–0.6C steels with high strength and ductility can also be achieved by introducing coherent disordered Cu‐rich precipitates to apply a Zener pinning force to slow down GB migration. [ 45 ] In thermoelectrics, the grain refinement effect has been frequently reported in several compounds doped with MgB 2 such as p‐type GeTe [ 46 ] and n‐type Bi 2 Te 3 ‐based alloys, [ 47 ] as well as p‐type Bi 0.4 Sb 1.6 Te 3 [ 48 ] and In 0.1 Sb 1.9 Te 3 . [ 49 ] However, the strengthening mechanisms upon MgB 2 addition are still elusive and require further investigation.…”

High‐Efficiency Thermoelectric Module Based on High‐Performance Bi0.42Sb1.58Te3 Materials

“…As may be seen from Figure S2b in the Supporting Information, the S 2 𝜎 obtained in this work is a considerably high value among the reported results of p-type Bi 2 Te 3 -based materials. [19,21,23,26,35,38,50,51] It should be noted that the average S 2 𝜎 rather than the maximum of S 2 𝜎 is beneficial for obtaining higher ZT ave and higher output power of the fabricated TE module. As may be seen from Figure 2f, we obtain a higher average S 2 𝜎 of 37 μW cm −1 K −2 between 300 and 500 K than the other samples with Ag-based compound doping.…”

The effects of tungsten doping on the mechanical properties of Bi2O2Se

“…materials, 18 and poor mechanical properties may lead to the reduction of the materials' yield and shorten the service time. 19 Considering that the Bi 2 O 2 Se is promising in making flexible electronics, it is thus of crucial importance to investigate its mechanical properties for its applications. [20][21][22] Thus far, the investigation of the mechanical properties of Bi 2 O 2 Se is still in its infancy stage.…”

“…However, unlike the other thermoelectric materials such as graphene, black phosphorus, the III–VI family of semiconductors, and the transition‐metal dichalcogenides (TMDs), 10–13 there is no van der Waals interaction between neighboring layers of Bi 2 O 2 Se, and weak electrostatic interactions are dominant, 1,14 which leads to significantly different mechanical properties of Bi 2 O 2 Se from other thermoelectric materials 10,15–17 . Generally, the assembling and manufacturing processes as well as reliable operation of devices require good mechanical property for materials, 18 and poor mechanical properties may lead to the reduction of the materials' yield and shorten the service time 19 . Considering that the Bi 2 O 2 Se is promising in making flexible electronics, it is thus of crucial importance to investigate its mechanical properties for its applications 20–22 …”