Size-dependent resistivity and thermopower of nanocrystalline copper

作者：Okram Gunadhor S; Kaurav Netram^*

来源：Journal of Applied Physics, 2011, 110(2): 023713.

DOI：10.1063/1.3610791

Nanocrystalline copper (NC-Cu) of average particle size (D) ranging from 29 to 55 nm was prepared using the polyol method. The compacted pellets of these nanoparticles were investigated using electrical resistivity (rho(n)) and thermopower (S-n) measurements in the temperature range from 5 to 300 K. The observed electrical resistivity and thermopower data for all the samples are typical of a good metal and the rho(n)(T) data are analyzed in the framework of the Bloch-Gruneisen theory. Our analysis indicates systematic departure from the bulk property for NC-Cu samples, decreasing effective Debye temperature, exponential decay of both the residual resistivity ratio (RRR) and the temperature coefficient of resistivity [alpha = (1/rho)d rho/dT] as D decreases, yet the Boltzmann theory of electron transport still holds true (k(F)l >> 1). Further, the validity of the Nordheim-Gorter rule is also discussed. The temperature dependence of S-n is found to be quite sensitive as compared to bulk thermopower S-Bulk behavior, revealing the evolution of S-n and exhibiting a significant enhancement of the phonon drag peak as D decreases. The present findings overall suggest the significant influence of the grain boundaries, surface atoms, and phonon confinement.

• 出版日期2011-7-15