Transport properties of AgPb 16 SbTe 18 prepared by the inclusion of nano AgSbTe 2 into PbTe matrix
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Transport properties of AgPb16SbTe18 prepared by the inclusion of nano AgSbTe2 into PbTe matrix M. A. Jalaja1 and Soma Dutta1,* 1
Materials Science Division, Council of Scientific and Industrial Research, National Aerospace Laboratories, Bangalore 560017, India
Received: 13 July 2020
ABSTRACT
Accepted: 19 August 2020
For the present investigation, AgPb16SbTe18 material was prepared by the inclusion of AgSbTe2 nanopowder into PbTe matrix, employing mechanical alloying route. This material was characterized for phase formation, microstructure, and transport properties. The microstructure showed densely populated grains with a grain size * 80 nm which plays an important role in controlling the transport properties. A remarkable enhancement in Seebeck coefficient (* - 500 lV at 450 K) value of AgPb16SbTe18 sample was observed which is attributed to the phonon scattering and the potential barrier, encountered by the charge carriers at the nanostructured grain boundaries. The other important findings are enhancement in electrical conductivity and reduction in thermal conductivity which directly enhance the figure of merit of the material and make it promising for thermoelectric power generator application in the mid-temperature zone.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Recent studies have shown the possibility of enhancing the thermoelectric performance of bulk materials apart from achieving it through low-dimensional structures like quantum dots, quantum well, and thin films. The excellent thermoelectric performance of these nanostructures arises from the quantum confinement effects which favor the fortification of the density of states in the vicinity of Fermi energy level offering remarkable improvement in Seebeck coefficient or by reducing the thermal conductivity by the prominent scattering of phonons at the interface [1–4]. The nanoscale engineering in
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https://doi.org/10.1007/s10854-020-04294-7
thermoelectrics has been demonstrated to be an effectual strategy to boost their performance by dropping the lattice thermal conductivity via the concomitant reduction in the mean free path for phonons due to the scattering at grain boundaries, but without increasing the mean free path for conducting carriers which helps in the consequential enhancement in the electric conductivity while preserving or rising the Seebeck coefficient [4–8]. However, these approaches can be considered as proof-of-concept studies. The real application of these low-dimensional structures poses significant challenges, like complex and expensive fabrication, uncertainty in the measurement, small-scale
J Mater Sci: Mater Electron
fabrication, and insignificant device performance [9]. But for large-scale production, nanostructuring needs an alternative cost-effective approach where essential criteria like low thermal conductivity, high Seebeck coefficient, and large power factor are part of it. In this context, the concept of using three-dim
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