The phonon scattering mechanism and its effect on the temperature dependent thermal and thermoelectric properties of a silver nanowire

Abstract

In this work, the electron–phonon, phonon–phonon, and phonon structure scattering mechanisms and their effect on the thermal and thermoelectric properties of a silver nanowire (AgNW) is investigated in the temperature range of 10 to 300 K. The electron–phonon scattering rate decreases with the increase of temperature. The phonon–phonon scattering rate increases with temperature and becomes greater than the electron–phonon scattering rate when the temperature is higher than the Debye temperature (223 K). The rate of phonon structure scattering is constant. The total phonon scattering rate decreases with temperature when the temperature is lower than about 150 K, and increases when the temperature is higher than 150 K. Correspondingly, the temperature dependent variation trend of the lattice thermal conductivity is opposite diametrically to that of the total phonon scattering rate. The thermoelectric properties of the AgNW are strongly coupled with the thermal conductivity via the phonon and electron transition. The thermoelectric properties of the material are quantified by the figure of merit (ZT). The ZT value of the AgNW is greater than that of bulk silver in the corresponding temperature range, and this difference increases with temperature. The order of the ZT of the AgNW is about 13 times greater than that of bulk silver at room temperature. The large increase of the ZT value of the AgNW is mainly due to the enhanced electron scattering and phonon scattering mechanisms in the AgNW.