由于尺寸效应和晶界效应的影响,纳米薄膜在导电和导热方面呈现出与体材料不同的性质.本文实验研究了不同厚度(20～54 nm)金薄膜在不同温度(100～340 K)的导电、导热性质.测量结果显示,薄膜的电导率和热导率比体材料小,洛伦兹数比体材料大,Wiedemann-Franz定律不再成立.随着厚度增加,薄膜的电导率,热导率和电阻温度系数都增加.薄膜热导率随温度变化趋势与体材料相反,随着温度升高而升高.电导率随温度变化趋势与体材料相同,随着温度升高而降低;但薄膜没有体材料对温度变化敏感,导致电阻温度系数下降.
Because of surface and grain boundary scattering,the metallic nanofilms exhibit different thermal and electrical properties compared with bulk metals.In this paper,several gold nanofilms with different thicknesses(20～54 nm)at different temperatures(100～340 K)are studied in experiment.The measured results show that the electrical and thermal conductivities of the nanofilms decrease greatly compared with the corresponding bulk value.However,the electrical conductivity drop is considerably greater than the thermal drop.It lcads to the Lorentz number of film larger than that in bulk.Both the thermal and electrical conductivities decrease as the films become thinner,and as the temperature increase,both of them increase.It is different from bulk to thermal conductivity while is consistent to electrical.However,the electrical conductivity of film is 1ess sensitive to temperature.It leads to the resistance temperature coefficient is smaller than in bulk.
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