Abstract
We investigated the thermoelectric properties of PbTe/Ag2Te bulk composites, synthesized by hand milling, mixing, and hot press sintering. From x-ray diffraction and energy dispersive x-ray spectroscopy measurements, we observed Ag2Te phase separation in the PbTe matrix without Ag atom diffusion. In comparison with previously reported pseudo-binary (PbTe)1−x(Ag2Te)x composites, synthesized by high temperature phase separation, the PbTe/Ag2Te bulk composites fabricated with a low temperature phase mixing process give rise to p-type conduction of carriers with significantly decreased electrical conductivity. This indicates that Ag atom diffusion in the PbTe matrix changes the sign of the Seebeck coefficient to n-type and also increases the carrier concentration. Effective p-type doping with low temperature phase separation by mixing and hot press sintering can enhance the thermoelectric performance of PbTe/Ag2Te bulk composites, which can be used as a p-type counterpart of n-type (PbTe)1−x(Ag2Te)x bulk composites.
Highlights
The thermoelectric (TE) energy conversion technology, which can directly convert waste heat into electricity and vice versa, has been extensively researched
We investigated the thermoelectric properties of pseudo-binary composite (PbTe)/Ag2Te bulk composites, synthesized by hand milling, mixing, and hot press sintering
Effective p-type doping with low temperature phase separation by mixing and hot press sintering can enhance the thermoelectric performance of PbTe/Ag2Te bulk composites, which can be used as a p-type counterpart of n-type (PbTe)1−x(Ag2Te)x bulk composites
Summary
The thermoelectric (TE) energy conversion technology, which can directly convert waste heat into electricity and vice versa, has been extensively researched. There are three different approaches with respect to manipulating the nanoparticle-in-alloy micro structure: (1) solid-state phase separation using precipitation, decomposition, and eutetic transformation;[5,9,10,11] (2) nanostructured powder sintering with high energy ball milling and spark plasma sintering or hot press;[12,13] and (3) nanoparticle dispersion into the TE matrix.[14,15] The above methods for introducing nano particle-inclusions are effective ways to disperse nano materials into the matrix in order to reduce the lattice thermal conductivity. The composites synthesized by low temperature extrinsic phase separation using the solution mixing process showed p-type transport of carrier and significantly reduced thermal conductivity. We can ascertain that the n-type change of the thermoelectric properties in the (PbTe)1−x(Ag2Te)x pseudo-binary system is due to the Ag2Te solid solution in the PbTe matrix
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