Influence of Nanopores on the Tensile/Compressive Mechanical Behavior of Crystalline CoSb3: A Molecular Dynamics Study

Abstract

Recently, many experimental studies have reported that inserting nanopores into thermoelectric materials can both remarkably reduce the thermal conductivity and significantly improve the thermoelectric performance of the target material. Research on nanoporous materials has thus been attracting much attention worldwide. However, most of the studies mainly focus on the preparation of nanoporous material and the effect of different geometrical sizes of nanopores on thermal conductivity and thermoelectric properties of the nanoporous material. In this paper, the mechanical behavior of crystalline CoSb 3 with nanopores under uniaxial tensile/compression is studied by means of the molecular dynamics method. The emphasis is on the influence of porosity, temperature and strain rate on the tensile/compressive mechanical behavior of nanoporous CoSb 3 . The simulation results show that both failure patterns under tension/compression are typical brittle fractures. The elastic modulus decreases with the growing porosity, and the porosity and the elastic modulus are inversely proportional to each other. The increase of temperature results in a linear degradation of the elastic modulus and the ultimate strength. The elastic modulus and the ultimate strength under uniaxial compression are greater than those under uniaxial tension. The present study sheds light on the future application of nanoporous CoSb 3 thermoelectric materials.

Brittle Failure Mechanism in Thermoelectric Skutterudite CoSb3

“…Because of its importance for engineering applications, the mechanical properties of CoSb 3 have been examined recently. − Rogl and Rogl reported experimental mechanical properties of doped skutterudite CoSb 3 such as elastic moduli, fracture toughness, and failure stress . They showed that CoSb 3 has mechanical properties competitive with other TE materials.…”

“…Yang et al used molecular dynamics simulations (Force field) to examine the stress–strain relationships of CoSb 3 and found it to be a typical brittle material . Li et al studied the tensile/compressive mechanical behavior of nanoporous skutterudite CoSb 3 thermoelectric material using molecular dynamics and found that elastic modulus of single crystalline CoSb 3 decreased with the increasing porosity. , However, the mechanism for brittle failure and the intrinsic mechanical properties of CoSb 3 remain unknown.…”

Molecular Dynamics approach for Fracture Simulation along a Weakly Bonded Interface

“…For calculating the per-atom stress, initially the stresses of all the atoms of the system were added together. The computed quantity was in units of pressure × volume (Li et al 2015), and the volume over which the stress is averaged (simulation box volume) was considered to be the characteristic volume. Hence, the total stress was divided by system volume to obtain the stress per atom (Li et al 2015) (Fig.…”