The thermoelectric properties at elevated temperature were investigated for n-type Bi2（Te,Se）3 which is obtained from ball milling processed powder with various milling times. Electrical properties such as electrica...The thermoelectric properties at elevated temperature were investigated for n-type Bi2（Te,Se）3 which is obtained from ball milling processed powder with various milling times. Electrical properties such as electrical resistivity and Seebeck coefficient are clearly dependent on milling time, in which the carrier concentration is attributed to the change of the electrical properties. The concentrations of the defects are also varied with the ball milling time, which is the origin of the carrier concentration variation. Even though finer grain sizes are obtained after the long ball milling time, the temperature dependence of the thermal conductivity is not solely understood with the grain size, whereas the electrical contribution to the thermal conductivity should be also considered. The highest figure of merit value of ZT = 0.83 is achieved at 373 K for the optimized samples, in which ball milling time is 10 h. The obtained ZT value is 48% improvement over that of the 0.5-h sample at 373 K.展开更多
In this study,the particle morphology,and size changes in copper and iron powders were investigated by using a high-energy ball mill under the same experimental conditions.The particle sizes and morphologies of the po...In this study,the particle morphology,and size changes in copper and iron powders were investigated by using a high-energy ball mill under the same experimental conditions.The particle sizes and morphologies of the powders were examined using a particle size analyzer and scanning electron microscopy(SEM).We also used the discrete element method(DEM)to analyze the ball impaction and the shear energy during the ball milling process.It was discovered that the quantity of milling balls and rotational speed had a major impact on energy dissipation through heat and plastic deformation as well as milling efficiency.The characteristic(particle morphology and size)of the iron and copper powder were differently changed under the same experimental conditions,shear energy,and ball impaction.When the particle sizes of copper and iron powder were compared under the same experimental conditions,the copper particle size increased from 21.6μm to 280μm,resulting in particle agglomeration,while the iron powder particle size decreased from 154μm to 4.35μm.展开更多
基金supported by the research fund of Hanbat National University in 2015
文摘The thermoelectric properties at elevated temperature were investigated for n-type Bi2（Te,Se）3 which is obtained from ball milling processed powder with various milling times. Electrical properties such as electrical resistivity and Seebeck coefficient are clearly dependent on milling time, in which the carrier concentration is attributed to the change of the electrical properties. The concentrations of the defects are also varied with the ball milling time, which is the origin of the carrier concentration variation. Even though finer grain sizes are obtained after the long ball milling time, the temperature dependence of the thermal conductivity is not solely understood with the grain size, whereas the electrical contribution to the thermal conductivity should be also considered. The highest figure of merit value of ZT = 0.83 is achieved at 373 K for the optimized samples, in which ball milling time is 10 h. The obtained ZT value is 48% improvement over that of the 0.5-h sample at 373 K.
基金supported by Unité de Catalyse et Chimie du Solide (UCCS)sponsor of scholarship: China scholarship council and School of Environment, Tsinghua University
基金supported by Changwon National University in 2023∼2024.
文摘In this study,the particle morphology,and size changes in copper and iron powders were investigated by using a high-energy ball mill under the same experimental conditions.The particle sizes and morphologies of the powders were examined using a particle size analyzer and scanning electron microscopy(SEM).We also used the discrete element method(DEM)to analyze the ball impaction and the shear energy during the ball milling process.It was discovered that the quantity of milling balls and rotational speed had a major impact on energy dissipation through heat and plastic deformation as well as milling efficiency.The characteristic(particle morphology and size)of the iron and copper powder were differently changed under the same experimental conditions,shear energy,and ball impaction.When the particle sizes of copper and iron powder were compared under the same experimental conditions,the copper particle size increased from 21.6μm to 280μm,resulting in particle agglomeration,while the iron powder particle size decreased from 154μm to 4.35μm.
