Low Lattice Thermal Conductivity (low + lattice_thermal_conductivity)

Distribution by Scientific Domains

Selected Abstracts

Microstructure-Lattice Thermal Conductivity Correlation in Nanostructured PbTe0.7S0.3 Thermoelectric Materials

Jiaqing He
Abstract The reduction of thermal conductivity, and a comprehensive understanding of the microstructural constituents that cause this reduction, represent some of the important challenges for the further development of thermoelectric materials with improved figure of merit. Model PbTe-based thermoelectric materials that exhibit very low lattice thermal conductivity have been chosen for this microstructure,thermal conductivity correlation study. The nominal PbTe0.7S0.3 composition spinodally decomposes into two phases: PbTe and PbS. Orderly misfit dislocations, incomplete relaxed strain, and structure-modulated contrast rather than composition-modulated contrast are observed at the boundaries between the two phases. Furthermore, the samples also contain regularly shaped nanometer-scale precipitates. The theoretical calculations of the lattice thermal conductivity of the PbTe0.7S0.3 material, based on transmission electron microscopy observations, closely aligns with experimental measurements of the thermal conductivity of a very low value, ,0.8,W,m,1,K,1 at room temperature, approximately 35% and 30% of the value of the lattice thermal conductivity of either PbTe and PbS, respectively. It is shown that phase boundaries, interfacial dislocations, and nanometer-scale precipitates play an important role in enhancing phonon scattering and, therefore, in reducing the lattice thermal conductivity. [source]

Enhancement of Thermoelectric Figure-of-Merit by a Bulk Nanostructuring Approach

Yucheng Lan
Abstract Recently a significant figure-of-merit (ZT) improvement in the most-studied existing thermoelectric materials has been achieved by creating nanograins and nanostructures in the grains using the combination of high-energy ball milling and a direct-current-induced hot-press process. Thermoelectric transport measurements, coupled with microstructure studies and theoretical modeling, show that the ZT improvement is the result of low lattice thermal conductivity due to the increased phonon scattering by grain boundaries and structural defects. In this article, the synthesis process and the relationship between the microstructures and the thermoelectric properties of the nanostructured thermoelectric bulk materials with an enhanced ZT value are reviewed. It is expected that the nanostructured materials described here will be useful for a variety of applications such as waste heat recovery, solar energy conversion, and environmentally friendly refrigeration. [source]

Analysis of Nanostructuring in High Figure-of-Merit Ag1,xPbmSbTe2+m Thermoelectric Materials

Bruce A. Cook
Abstract Thermoelectric materials based on quaternary compounds Ag1,xPbmSbTe2+m exhibit high dimensionless figure-of-merit values, ranging from 1.5 to 1.7 at 700,K. The primary factor contributing to the high figure of merit is a low lattice thermal conductivity, achieved through nanostructuring during melt solidification. As a consequence of nucleation and growth of a second phase, coherent nanoscale inclusions form throughout the material, which are believed to result in scattering of acoustic phonons while causing only minimal scattering of charge carriers. Here, characterization of the nanosized inclusions in Ag0.53Pb18Sb1.2Te20 that shows a strong tendency for crystallographic orientation along the {001} planes, with a high degree of lattice strain at the interface, consistent with a coherent interfacial boundary is reported. The inclusions are enriched in Ag relative to the matrix, and seem to adopt a cubic, 96 atom per unit cell Ag2Te phase based on the Ti2Ni type structure. In-situ high-temperature synchrotron radiation diffraction studies indicated that the inclusions remain thermally stable to at least 800,K. [source]

Improved Thermoelectric Properties of Cu-Doped Quaternary Chalcogenides of Cu2CdSnSe4

Min-Ling Liu
The chalcopyrite-like structure of Cu2MSnQ4 is an ordered tetrahedral array of flattened CuQ4 and undistorted MQ4 and SnQ4, with a low lattice thermal conductivity. The [Cu2Q4] tetrahedral layers are electrically conducting, and the [SnMQ4] layers are electrically insulating. [source]

Synthesis and thermoelectric properties of YbSb2Te4

Amado S. Guloy
Abstract The study of the ternary phase diagram Yb,Sb,Te has led to the synthesis of YbSb2Te4 as a pure phase by way of high energy ball milling followed by annealing, whereas typical high temperature powder metallurgy leads to multiphase sample with impurities of the very stable YbTe. The Hall mobility, Seebeck coefficient, electrical resistivity and thermal conductivity of the layered compound YbSb2Te4 were measured in the range of 20,550 C. The thermoelectric figure of merit peaks at 525 K and reaches 0.5. Of particular interest is the very low lattice thermal conductivity (as low as a glass) which makes YbSb2Te4 and related compounds promising thermoelectric materials. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]