Enhanced Thermoelectric Properties in the Counter-Doped SnTe System with Strained Endotaxial SrTe

Abstract

We report enhanced thermoelectric performance in SnTe, where significantly improved electrical transport properties and reduced thermal conductivity were achieved simultaneously. The former was obtained from a larger hole Seebeck coefficient through Fermi level tuning by optimizing the carrier concentration with Ga, In, Bi, and Sb dopants, resulting in a power factor of 21 μW cm(-1) K(-2) and ZT of 0.9 at 823 K in Sn(0.97)Bi(0.03)Te. To reduce the lattice thermal conductivity without deteriorating the hole carrier mobility in Sn(0.97)Bi(0.03)Te, SrTe was chosen as the second phase to create strained endotaxial nanostructures as phonon scattering centers. As a result, the lattice thermal conductivity decreases strongly from ∼2.0 Wm(-1) K(-1) for Sn(0.97)Bi(0.03)Te to ∼1.2 Wm(-1) K(-1) as the SrTe content is increased from 0 to 5.0% at room temperature and from ∼1.1 to ∼0.70 Wm(-1) K(-1) at 823 K. For the Sn(0.97)Bi(0.03)Te-3% SrTe sample, this leads to a ZT of 1.2 at 823 K and a high average ZT (for SnTe) of 0.7 in the temperature range of 300-823 K, suggesting that SnTe is a robust candidate for medium-temperature thermoelectric applications.

A Review on Low-Grade Thermal Energy Harvesting: Materials, Methods and Devices

“…TE materials based on group-IV tellurides, such as PbTe [59], GeTe [60,61,62], and SnTe [63,64,65] are normally suggested for mid-temperature range application (500–900 K) [66,67]. Among them, PbTe is the most widely used TE material and has maximum ZT in range of 0.8–1.8 above 700 K. PbTe can be doped with appropriate dopants, such as I and Tl [68,69,70], in order to tune the optimal temperature and enhance the ZT value.…”

Investigation of the bipolar effect in the thermoelectric material CaMg2Bi2 using a first-principles study

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The TE conversion efficiency and performance-price ratios of TE devices developed so far and those under development are insufficient to compete with fossil fuel based energy resources. Some intrinsic issues need to be solved for TE materials design and synthesis, and some of them have been lasting for decades.…”

Large-Scale Surfactant-Free Synthesis of p-Type SnTe Nanoparticles for Thermoelectric Applications

“…S increases from ~34.5 μV·K −1 at 300 K, to ~55.8 μV·K −1 at 530 K (Figure 6b). It should be noted that σ and S are relatively low and high, respectively, compared to those of SnTe bulk materials synthesised by high energy ball milling [18] and high-temperature methods [26,28,29], which could result from the influence of impurities (i.e., SnO 2 and Te) and/or the relatively low Sn vacancy concentration (no deviation in the Sn site occupancy from unity could be identified by Rietveld refinement, for example, which would support this premise). The power factor ( S 2 σ) of SnTe increases from ~0.30 mW·m −1 ·K −2 at 300 K, to ~0.43 mW·m −1 ·K −2 at 530 K (Figure 6c).…”

“…For example, strategies such as band structure engineering, via the introduction of resonant impurity levels through In doping [18] and band convergence through Cd [19], Mg [20], Hg [21], Mn [22], or Ag alloying [23], have been applied to improve the power factor ( S 2 σ) of SnTe. Equally, solid solution alloying [24,25], nanostructuring [18,19,25,26,27,28,29,30], introducing interstitial atoms [31], and all-scale hierarchical architecturing [22], have been used to minimise the thermal conductivity by enhanced phonon scattering, pushing ZT to ~1.1–1.3 at ~823–873 K [18,19,20,29], and ~1.3–1.4 at ~900–923 K [21,22,26]. Nonetheless, the synthesis of SnTe requires time-consuming and energy-intensive processes, such as the heating, melting and annealing of precursor materials at high temperatures (~973–1423 K) [19,20,21,22,23,24,25,26,28,29,30,31,32,33].…”