Increased Seebeck Coefficient and Decreased Lattice Thermal Conductivity in Grain-Size-Controlled p-Type PbTe–MgTe System

Abstract

PbTe systems are known as good thermoelectric materials for midtemperature range applications. Here, we demonstrate that a method of melt-spinning followed by pulsed electric current sintering is effective to synthesize nanostructured bulk PbTe with enhanced thermoelectric properties. The bulk samples with the nominal composition PbTe−2% MgTe doped with 4% Na consist of a hierarchical nanostructure, where MgTe-based nanoprecipitates with the size of ∼2−15 nm exist in the PbTe grains that are several hundred nm in size. Both the nanoscale precipitates and the high-density grain boundaries effectively scatter heat-carrying phonons, leading to significant reduction in the lattice thermal conductivity. Furthermore, an increased Seebeck coefficient is observed, which can be explained by band convergence induced by alloying Mg and energy filtering induced by grain boundaries. The simultaneous realization of the decreased lattice thermal conductivity and increased Seebeck coefficient results in the enhanced thermoelectric figure of merit zT to be around 1.3 at 753 K.

Thermoelectric power generation: from new materials to devices

“…Because the ZT of PbTe-based materials has now been dramatically boosted through the new strategies discussed above [28,30,[170][171][172][173][174], recently we achieved higher η max in nanostrucuted Pb-based modules than the old PbTe modules [38,154] and diffusion barriers (figure 6a). For the new PbTe-based modules, Fe-, Ni and Nb-based alloys were investigated as diffusion barriers [38,[175][176][177][178][179].…”

Inkjet‐Printed Flexible Spin Seebeck Thermopile Device for Low‐Cost Spintronics Device Fabrication

“…Additionally, a material with a small grain size has low thermal conductivity, which enhances thermoelectric performance. [ 37 ] Therefore, the inkjet‐printed NP‐assembled film is a suitable material for a thermoelectric generator owing to its low thermal conductivity.…”

Cobalt germanide precipitates indirectly improve the properties of thermoelectric germanium antimony tellurides

“…For instance, precursors prepared by melt-spinning of Bi/Sb/Te alloys did not always enhance the thermoelectric performance of Bi 2 Te 3based materials due to the rapid grain growth during SPS; and PbTe with nanoscale MgTe precipitates obtaines by MS/SPS exhibits rather similar zT values compared to corresponding ingots. 80,81 SEM backscattered-electron orientation (''channeling'') contrast imaging with respect to the (sub-)grain size of the GST matrix material shows a significant difference in case of waterquenched samples. Introducing cobalt germanide precipitates into the GST matrix leads to an enhancement concerning thermoelectric performance of samples with microstructures that contain small grains and/or subgrains.…”