Impact of particle size and surfactant on electrical resistivity and thermopower of silver nanoparticles

Abstract

We report here the critical role of crystallite size and surfactant of Ag nanoparticles on electrical resistivity and thermopower in the temperature range of 5 K–300 K. The Debye temperature (θD) decreases as the crystallite size decreases; latter's decrease corresponds to increase in the trioctylphosphine quantity. The θD decrease is ~36% in the sample with crystallite size of 15.1 nm compared to the bulk Ag. The usual phonon drag peak in thermopower for the bulk Ag becomes phonon drag minimum (PDM) in these nanoparticles. The PDM positions get gradually suppressed and shifted towards lower temperature with decrease in the crystallite size. They are attributed to the modifications in the overall electron-phonon interactions due to spatial confinement of electrons, variation in barrier heights, charge-transfer among metal NPs and surfactant, and enhanced disorder.