Microstructure investigations and thermoelectrical properties of an N-type magnesium–silicon–tin alloy sintered from a gas-phase atomized powder

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

“…Pointwise EDX shows a small variation in the material composition Mg A Ge B Sn C (Li has not been detected), with 1.985 < < 1.996, 0.358 < < 0.391, and 0.613 < < 0.657.The brighter grains are slightly Sn rich compared to the darker ones. This coexistence of neighboring phases with similar but distinct compositions has been observed previously for Mg 2 Si based solid solutions [45]. However, the differences are very small so that the material will be treated as single phase material for the electronic transport discussion.…”

High efficiency Mg2(Si,Sn)-based thermoelectric materials: scale-up synthesis, functional homogeneity, and thermal stability

“…All samples reach a value of around 1000 U À1 cm À1 at $773 K which is quite comparable with the values previously reported for Bi-doped Mg 2 (Si,Sn) with similar composition. 15,17,43 Although the Seebeck values of these samples are similar to those of the Mg 2 Si 0.5875 Sn 0.4 Sb 0.0125 samples synthesized using gas atomization technique, 48 the initial electrical conductivities ($2500 U À1 cm À1 ) are around 25% higher, which could be attributed to both higher doping level (higher carrier concentration) and optimum Sn content leading to less alloy scattering (i.e. higher carrier mobility).…”

“…17 The Mg 2 Si 0.5875 Sn 0.4 Sb 0.0125 sample synthesized using gas atomization showed slightly lower thermal conductivity at high temperatures (>700 K), which could be due to more alloy scattering (less Sn substitutions), less bipolar contribution (larger band gap originating from lower Sn content), and smaller grain sizes. 48 The lattice and bipolar contributions to the thermal conductivity, k ph + k bipolar , were extracted from the total thermal conductivity ( Fig. 4), k, by deducting the electronic part of the thermal conductivity, k e , which was calculated employing the Wiedemann-Franz law, k e ¼ L  s  T. To calculate k e , the temperature dependence of the Lorenz number, L, was obtained through the L (10 À8 V 2 K À2 ) ¼ 1.5 + exp[À|S|/116 mV K À1 ] equation, where S is in mV K À1 , and L is expressed in 10 À8 V 2 K À2 .…”

“…All in all, the materials obtained from this scalable synthesis route not only show a high performance zT reaching around 1.3 at 773 K, but also are scalable and stable under heat treatment up to 720 hours. To the best of our knowledge, there are very few reported works on the successful large scale synthesis of high efficiency magnesium silicide-based compounds; aside from our method, the other approaches include gas atomization 48 and solid state reaction. 50 On the one hand, the gas atomization was successful in producing large quantities of material with high performance (zT max $ 1.4 at 800 K), but the apparatus is not easily accessible and operable in usual material science laboratories.…”

Upscaled Synthesis of n‐ and p‐Type Thermoelectric Skutterudite Single Legs by Gas Atomization and Current‐Assisted Sintering

“…For the work presented here a small‐scale gas atomizer was used that allows for a material production of 0.5–3 kg of powder per batch which overcomes the threshold from laboratory‐style ampoule melting synthesis to a high‐throughput one‐step powder production method. The method is easily scalable from kilograms to tons per batch and thus allows for a fast and flexible production of thermoelectric material powders as has already been investigated for Bi 2 Te 3 ‐Bi 2 Se 3 compounds, Mg 2 (Si,Sn), and for Ce‐filled n‐type Skutterudites . In this work we present investigations on undoped and on both p‐type and n‐type Skutterudites with various filling elements synthesized using gas atomization and subsequent current‐assisted sintering.…”