Compressive Fatigue Behavior and Its Influence on the Thermoelectric Properties of p-Type Bi_0.5Sb_1.5Te₃ Alloys

Abstract

BiSbTe alloy is one of the most important thermoelectric materials that has been commercialized for large-scale applications in waste heat recovery and spot cooling. However, its practical application often involves complicated service conditions, such as substantial dynamic vibrational stresses as well as long-term exposure to the large thermal gradient that usually generates high thermal stress. Thus, it is of vital importance to investigate the mechanical response and the evolution of microstructure and thermoelectric performance of BiSbTe alloy under the quasi-static force and dynamic compressive stress. Herein, we elucidate the compressive fatigue behavior and its influence on the thermoelectric performance of p-type Bi0.5Sb1.5Te3 materials prepared by melt spinning and subsequent plasma-activated sintering. The fatigue life was tested at various stress ratios ranging from 60 to 90%. The microstructure evaluation indicates that repetitive loading of compressive stress contributes to largely accumulated strains and dislocations near grain boundaries. With the increasing cycling numbers, the magnitude of accumulated strains reaches the critical level and leads to microcrack initiation and propagation of fatigue cracks. The cyclic compressive stress resulted in the marked degradation of thermoelectric performance in Bi0.5Sb1.5Te3 material due to the strong suppression of carrier mobility by the fatigue-induced defects. This work can provide important guidance for the practical applications of p-type Bi0.5Sb1.5Te3 material.

Thermal Stability and Mechanical Response of Bi2Te3-Based Materials for Thermoelectric Applications

“…The recent study has reported the compressive fatigue behavior of p-type Bi 0.5 Sb 1.5 Te 3 material fabricated by the MS-PAS method. 105 The fatigue life increases significantly up to 9 × 10 5 when the stress ratio decreases to 60% (i.e., equals to 68 MPa), approaching the fatigue limit (10 6 ), as shown in Figure 10a. Thus, the fatigue strength limit of MS-PAS-prepared Bi 0.5 Sb 1.5 Te 3 material is nearly 68 MPa.…”

“…These external fields usually bring about fatigue or creep phenomena which will inevitably degrade both TE and mechanical performances. The recent study has reported the compressive fatigue behavior of p-type Bi 0.5 Sb 1.5 Te 3 material fabricated by the MS-PAS method . The fatigue life increases significantly up to 9 × 10 5 when the stress ratio decreases to 60% (i.e., equals to 68 MPa), approaching the fatigue limit (10 6 ), as shown in Figure a.…”

“…The inset shows the enlarged view of the σ m −N f plot. Reproduced with permission 105. Copyright 2019, American Chemistry Society.…”

Mechanical Properties and Thermal Stability of the High-Thermoelectric-Performance Cu2Se Compound

“…To date, most research was focused on enhancing the thermoelectric performance of Cu 2 Se materials. It is noteworthy that during the long-term service, thermoelectric materials are exposed to thermal shock, thermal cycling, and mechanical vibration, which require materials with robust mechanical properties. − However, the existing literature was focused on some specific aspects of the mechanical performance, − and the systematic study of the mechanical behavior of Cu 2 Se materials was rarely reported. Moreover, for large-scale application, excellent thermal stability is also of equal significance as excellent thermoelectric performance. − At high temperatures, the composition and microstructure vary with duration time due to the intensified interdiffusion of atoms, and especially for Cu 2 Se, the long-range migration of liquid-like Cu + would accelerate thermal fatigue, deteriorating the thermoelectric performance and further causing the failure of thermoelectric modules.…”

Phonon Engineering for Thermoelectric Enhancement of p-Type Bismuth Telluride by a Hot-Pressing Texture Method

“…These works indicated that reducing lattice thermal conductivity by multi-scale defects is indeed a very promising scheme to significantly improve the TE properties of Bi 2 Te 3 -based sintered materials. It is also found that many of obtained κ tot values are still at some high level, and there is still room for further improvement of the TE performance. − Additionally, some synthetic methods may need some simplifications to meet the requirement of large-scale applications.…”