Understanding the combustion process for the synthesis of mechanically robust SnSe thermoelectrics

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn1 − xSe via anisotropy and vacancy synergy

“…The large crystals lead to a considerable anisotropy in the sintered pellets, and the high Sn vacancy level contributes to an optimum p of $2.3 × 10 19 cm −3 and in turn a high S 2 σ of $7.4 μW cm −1 K −2 at 823 K, measured along the direction perpendicular to the sintering pressure. Simultaneously, a low κ of $0.41 W m −1 K −1 is achieved by effective phonon scattering at localized crystal imperfections including lattice distortions, grain boundaries, and vacancies, as illustrated in Figure 1B, and confirmed by detailed structural characterizations, leading to a high ZT of $1.5 at 823 K. This value is very competitive compared with previous studies focusing on pure polycrystalline SnSe via different fabrication techniques, 31,32,39,[42][43][44] as shown in Figure 1C. Figure 1D shows that the achieved average ZT of $0.78 is also a record for pure polycrystalline SnSe according to previous results.…”

“…In this situation, to achieve high ZTs in pure SnSe with acceptable mechanical properties is much significant and promising for applying to thermoelectric devices. 39 In order to achieve high ZTs in pure polycrystalline SnSe, a key point is to tune an appropriate n or p, which can optimize the electrical transport properties 2,5 as discussed above. To achieve this goal, aqueous solution routes such as hydrothermal and solvothermal syntheses are good choices, 2 owing to their abilities to directly tune cation or anion vacancy concentrations under supercritical conditions, including high temperature and high vapor pressure of solvents.…”

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

“…However, solvothermal is a good choice to meet the goal of simultaneously improving the thermoelectric and mechanical properties. It was reported that at a strain rate of 2.5 × 10 −4 s −1 , competitive compressive strength of ≈52.1 and ≈77.0 MPa can be achieved along the ⊥ and // directions for solvothermally synthesized Sn 1− x Se ( x = 0.025),170 respectively, and both of which are very competitive with reported record value of 74.4 MPa achieved by a combustion method 95. This value is also comparable to the other commercial thermoelectric materials, such as PbTe and Bi 2 Te 3 312,313.…”

High-performance SnSe thermoelectric materials: Progress and future challenge

“…For polycrystalline SnSe, the mechanical properties, including compressive strength, bending strength, hardness, fracture toughness, fracture strength, and thermal shock resistance, all exhibits values that are comparable to those reported for other state-ofthe-art thermoelectric materials. The compressive strength and bending strength of the as-synthesized polycrystalline SnSe were 74.7 MPa and 40.6 MPa [150], respectively.…”

“…It is different from the traditional hot-pressing for that the heat generation is internal during SPS process, and the heat is provided by external heating elements during hot-pressing. For SnSe, SPS can achieve a very high heating and cooling rate (up to 1000 K min -1 ), resulting in a very fast sintering process (within several minutes) [150]. SPS has the great potential of To exam the existence and dispersion of dopants, EDS mapping is also frequently used.…”