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中国物理学会期刊

并联模型研究双层热电薄膜热电性能

Study of parallel models for thermoelectric properties of double-layer thermoelectric thin films

CSTR: 32037.14.aps.72.20231259
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  • 目前, 热电双层膜的电输运性能测量及预测一般采用并联模型理论, 然而并联模型使用条件缺乏理论和实验的支持和验证. 本文借助于COMSOL Multiphysics软件采用有限元理论模拟得到了Cu/Si, Ag/Si双层膜在施加温度差下的塞贝克系数, 并与并联模型进行比较. 研究双层膜两端是否镀金属Pt层、双层膜之间插入高阻/低阻/绝缘界面对双层膜的塞贝克系数测量结果的影响. 研究发现, 当冷热端无Pt时, 高阻和电绝缘界面时Si和Cu两侧电势分别沿温度梯度方向均匀分布, 测得其塞贝克系数分别与材料本身的值相同, 低阻界面时Cu侧热电势随着探针间距L均匀变化, Si侧呈现非均匀变化. 有Pt时, Cu和Si侧的热电势沿着温度梯度的方向分布均匀, 无论在绝缘/高阻/低阻界面中, Si和Cu两侧测量值均与Cu塞贝克系数相同. 实验研究了Si/Ag和Bi/Ag双层膜, 无Pt时, Si/Ag双层膜Si侧的塞贝克系数的绝对值随着温度的降低而降低, 但是Ag侧塞贝克系数的绝对值随着温度的降低而升高. 有Pt时, Bi/Ag双层膜两侧的塞贝克系数相同.

     

    Currently, the measurement and prediction of the electrical transport performance of thermoelectric double-layer membrane is often based on the theory of parallel model. However, the conditions under which the parallel model can be used lack theoretical and experimental support and validation. In this work, the Seebeck coefficients of Cu/Si and Ag/Si bilayers under applied temperature difference are obtained by using finite element theory simulations with the help of COMSOL Multiphysics software and compared with the results from the parallel model. Whether the ends of the bilayer plated with a metal Pt layer, and the insertion of a high-resistance/low-resistance/insulation interface between the bilayers affect the Seebeck coefficient measurements of the bilayer are investigated. It is found that when there is no Pt at the hot end or cold end, the potentials on the Si side and Cu side at the high-resistance and electrically insulating interfaces are uniformly distributed along the direction of the temperature gradient, respectively, and the measured Seebeck coefficients are the same as the values of the materials’ own, respectively, and the thermal potential on the Cu side at the low-resistance interface varies uniformly with the probe spacing L, while the thermal potential on the Si side shows a non-uniform variation. With Pt, the thermal potentials on the Cu side and Si side are uniformly distributed along the direction of the temperature gradient, and the measured values on both Si side and Cu side are the same as the Cu Seebeck coefficients, regardless of the insulating/high-resistance/low-resistance interface. The Si/Ag and Bi/Ag bilayers are investigated experimentally. In the absence of Pt, the absolute value of the Seebeck coefficient on the Si side of Si/Ag bilayer decreases with temperature decreasing, but the absolute value of the Seebeck coefficient on the Ag side increases with temperature decreasing. In the presence of Pt, the Seebeck coefficients on both sides of the Bi/Ag bilayer membrane are equal.

     

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