The peak dimensionless thermoelectric figure-of-merit (ZT) of Bi(2)Te(3)-based n-type single crystals is about 0.85 in the ab plane at room temperature, which has not been improved over the last 50 years due to the high thermal conductivity of 1.65 W m(-1) K(-1) even though the power factor is 47 x 10(-4) W m(-1) K(-2). In samples with random grain orientations, we found that the thermal conductivity can be decreased by making grain size smaller through ball milling and hot pressing, but the power factor decreased with a similar percentage, resulting in no gain in ZT. Reorienting the ab planes of the small crystals by repressing the as-pressed samples enhanced the peak ZT from 0.85 to 1.04 at about 125 degrees C, a 22% improvement, mainly due to the more increase on power factor than on thermal conductivity. Further improvement is expected when the ab plane of most of the small crystals is reoriented to the direction perpendicular to the press direction and grains are made even smaller.
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http://dx.doi.org/10.1021/nl101156v | DOI Listing |
Heliyon
January 2025
Department of Physics, University of Rajshahi, Rajshahi, 6205, Bangladesh.
The present study focuses on the ground state mechanical, acoustic, thermodynamic and electronic transport properties of NaSbS polymorphs using the density functional theory (DFT) and semi-classical Boltzmann transport theory. The mechanical stability of the polymorphs is affirmed by the calculated elastic tensor. The calculated elastic properties asserted that all the polymorphs exhibit soft, brittle, anisotropic nature containing dominant covalent bonding.
View Article and Find Full Text PDFInt J Thermophys
January 2024
Material Measurement Laboratory, Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO 80305, USA.
The thermal conductivity of liquid -1,2-dichloroethene (R-1130(E)) was measured at temperatures ranging from 240 K to 340 K and pressures up to 25 MPa using a transient hot-wire instrument. A total of 447 thermal conductivity data points were measured along six isotherms. Each isotherm includes data at nine pressures, which were chosen to be at equal density increments starting at a pressure of 0.
View Article and Find Full Text PDFMater Horiz
January 2025
State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, People's Republic of China.
Given extremely high porosity, aerogels have demonstrated remarkable advantages in serving as thermal insulation and wave-transparent materials. Unfortunately, their practical applications are greatly confined by their inherent fragility. The recent emergence of polymer aerogels presents an ideal platform for the development of flexible aerogel films.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States.
Biogenic-based foam, renowned for its sustainable and eco-friendly properties, is emerging as a promising thermal insulating material with the potential to significantly enhance energy efficiency and sustainability in building applications. However, its relatively high thermal conductivity, large-pore configurations, and energy-intensive manufacturing processes hinder its widespread use. Here, we report on the scalable, one-pot synthesis of biogenic foams achieved by integrating recycled paper pulp and in situ nanoporous silica formation, resulting in a hierarchical structure comprising both micropores and nanopores.
View Article and Find Full Text PDFACS Nano
January 2025
Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Radiative cooling is an emerging zero-energy-consumption technology for human body cooling in outdoor scenarios during hot seasons. However, existing radiative cooling textiles are limited by low intrinsic cooling power, high hydrophobicity, and heat-insulating properties, which seriously impede a satisfying cooling effect, perspiration-wicking, and heat dissipation, thus limiting human thermal comfort in practical situations. Here, we developed a radiative cooling meta-fabric that was integrated with high perspiration-wicking and thermal conduction capacity.
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