Impact of Se in Structural, Mechanical, Thermal, Thermoelectric and Optical Properties of n-type SnTe

Abstract

Lead-free SnTe compound is an alternative material for thermoelectric devices offering suitable band gap, non-toxicity, and mechanical stability. Here the structural, electronic, mechanical, thermal, thermoelectric, and optical properties of parent binary SnTe and ternary SnTe0.125Se0.875, SnTe0.25Se0.75, SnTe0.5Se0.5, SnTe0.75Se0.25, SnTe0.875Se0.125 materials are discussed at ambient conditions using full-potential linearized augmented plane wave method based on density functional theory. To make an accurate band gap we have used the mBJ scheme for the parent compound. The stability of the materials was confirmed using their calculated elastic constants. From the calculated mechanical properties, we have noted that the SnTe0.25Se0.75 material is more ductile and the SnTe0.875Se0.125 material has more hardness and a more brittle nature compared to other materials. We have computed the Seebeck coefficient, electrical conductivity, and power factor value in the temperature range of 300 to 1000 K in steps of 100 K using Boltzmann transport theory interfaced with the Wien2k program. From the thermoelectric properties, the ternary SnTe0.5Se0.5 havs a high power factor due to maximum electrical conductivity and is identified as a potential compound for thermoelectric applications. From the calculated optical results, the series of SnTe combinations are deemed suitable materials for optoelectronic applications. Our theoretical results are agreed well with available experimental results.

Optimization of Mechanical and Thermoelectric Properties of SnTe‐Based Semiconductors by Mn Alloying Modulated Precipitation Evolution

“…In this case, β is found to be 0.18 for FCC, [ 34 ] shear modulus G and Burgers vector b are ≈31.6 GPa [ 35 ] and ≈0.39 nm [ 36 ] for SnTe material, d and d 0 represent the average grain size of x = 0.10 and x = 0 samples, respectively. Given the slight difference in average grain size between x = 0 and x = 0.10 samples, the strength contribution of grain refinement to σ Y can be reasonably calculated to be ≈1.0 MPa.…”

“…The existence of precipitates is an important factor affecting the migration of dislocations. The contribution of precipitation strengthening to the improvement of yield strength can be estimated by the following equation: [ 40–42 ] $$$$\begin{equation}\Delta {\sigma }_p = M\frac{{0.4Gb}}{{\pi \lambda \sqrt {1 - \upsilon } }}\ln \left( {\frac{{2{r}_s}}{b}} \right)\end{equation}$$$$where ν is the Poisson's ratio of ≈ 0.33, [ 35 ] λ represents the mean inter‐precipitate distance calculated by: [ 40,43 ] $$$$\begin{equation}\lambda = 2{r}_s\left( {\sqrt {\frac{\pi }{{4f}}} - 1} \right)\end{equation}$$$$ r s = (2/3) 1/2 r denotes the mean radius of a circular cross‐section in a random plane for precipitates. [ 42 ] Assuming that precipitates are spherical and distributed on a cubic grid, a statistic is carried based on several HAADF images and the mean precipitate radius r and volume fraction of precipitation f have roughly calculated to ≈12 nm and ≈0.17%, respectively.…”

“…where 𝜈 is the Poisson's ratio of ≈ 0.33, [35] 𝜆 represents the mean inter-precipitate distance calculated by: [40,43]…”

Constructing Coated Grain Nanocomposites and Intracrystalline Precipitates to Simultaneously Improve the Thermoelectric and Mechanical Properties of SnTe by MgB2 and Sb Co‐Doping

“…where 𝛽 is a constant of 0.18 depending on the crystal structure (FCC), G is the shearing module (≈31.6 GPa), [61] and b is the Burgers vector (≈0.39 nm). [62] d and d 0 are the average grain size of MgB 2 or MgB 2 -Sb co-doped samples, and the Sn 1.03 Te matrix, respectively.…”

“…where 𝜈 is the Poisson's ratio (≈0.33), [61] 𝜆 represents the mean inter-precipitate distance that can be calculated using the equation below: [67,70]…”