Thermoelectric properties of lead chalcogenide core-shell nanostructures

We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and the possibility of energy filtering as opposed to grain boundary scattering as an explanation is discussed. A decreased Debye temperature and an increased molar specific heat are in accordance with recent predictions for nanostructured materials. On the basis of these results we propose suitable core-shell material combinations for future thermoelectric materials of large electric conductivities in combination with an increased thermopower by energy filtering.Comment: 12 pages, 8 figure

Thermoelectric generator (TEG) technologies and applications

2021 The Author(s). Nowadays humans are facing difficult issues, such as increasing power costs, environmental pollution and global warming. In order to reduce their consequences, scientists are concentrating on improving power generators focused on energy harvesting. Thermoelectric generators (TEGs) have demonstrated their capacity to transform thermal energy directly into electric power through the Seebeck effect. Due to the unique advantages they present, thermoelectric systems have emerged during the last decade as a promising alternative among other technologies for green power production. In this regard, thermoelectric device output prediction is important both for determining the future use of this new technology and for specifying the key design parameters of thermoelectric generators and systems. Moreover, TEGs are environmentally safe, work quietly as they do not include mechanical mechanisms or rotating elements and can be manufactured on a broad variety of substrates such as silicon, polymers and ceramics. In addition, TEGs are position-independent, have a long working life and are ideal for bulk and compact applications. Furthermore, Thermoelectric generators have been found as a viable solution for direct generation of electricity from waste heat in industrial processes. This paper presents in-depth analysis of TEGs, beginning with a comprehensive overview of their working principles such as the Seebeck effect, the Peltier effect, the Thomson effect and Joule heating with their applications, materials used, Figure of Merit, improvement techniques including different thermoelectric material arrangements and technologies used and substrate types. Moreover, performance simulation examples such as COMSOL Multiphysics and ANSYS-Computational Fluid Dynamics are investigated

Microstructure engineering design for thermoelectric materials : an approach to minimize thermal diffusivity

An alloy engineering approach aiming to produce a fine two-phase mixture thermoelectric material is highlighted in order to reduce the thermal diffusivity. We utilized the spinodal decomposition in the PbTe-GeTe quasi-binary system to control the alloy microstructure through solutioning, quenching and aging treatments. The effect of various microstructural states on the thermal diffusivity is analyzed. It is observed that a minimum in thermal diffusivity is obtained when several microstructural contributions are combined

Structural aspects of changes induced in PbTe by doping with Mn, In and Ga

The paper presents the extended results of structural investigations of Pb0.9Mn0.1Te, and Pb0.9Mn0.1Te systems doped with In (2 at.%) and Ga (4 at.%) by means of EXAFS (extended X-ray absorption fine structure) technique. EXAFS measurements performed at Te-, Mn-, In- and Ga-K absorption edges at different temperatures are complemented with X-ray diffraction, flame absorption and X-ray fluorescence analysis. That way the complete information about elemental concentration; crystal structure; local environment around constitutive and impurity atoms (including their displacements from the regular lattice positions); local and long-range ordering; and the overall influence of doping on the host crystal structure is derived. The obtained results represent an important step towards understanding the structural aspects of doping of lead telluride-based semiconductors with Mn and group III elements and their connection to electronic and optical phenomena important for their applications