(Color online) XRD patterns of different mole ratio nanocrystalline copper samples, 0.03 (D = 29 nm), 0.05 (D = 37 nm), 0.07 (D = 45 nm), and 0.10 (D = 55 nm), as indicated.
(Color online) AFM image (left) and particle size distribution (right) of 0.03 mole ratio sample (D = 29 nm).
(Color online) Variation of electrical resistivity with temperature for compacted NC-Cu samples for various particle sizes. The solid line represents the theoretical fit using the Bloch-Grüneisen relation [equation (2)]. The inset shows the electrical resistivity with the temperature axis in a logarithmic scale in order to show more clearly the low-temperature behavior of the resistivity.
(Color online) The variation of residual resistance ratio (right axis) and temperature coefficient of resistivity (α) (left axis) with the particle size (D). The plot of [ρ(T)−ρ(4.2 K)]/ρ(θD ) as a function of T/θD is shown in the inset.
(Color online) Variation of thermopower of compacted NC-Cu samples with temperature. The thermopower of copper standard is also shown.
(Color online) Diffusion and phonon drag contributions of various NC-Cu samples. S/T is found to be linear with T 2 below 50 K. The inset shows the plots of coefficients A and B in Eq. (3) against particle size.
(Color online) Diffusion and phonon drag contributions of various NC-Cu samples. S/T is found to be linear with 1/T 2 above 150 K. The inset shows the plots of coefficients A and B in Eq. (4) against particle size.
(Color online) Difference in thermopower, ΔS, of compacted NC-Cu samples.
(Color online) The plot for S − SD as a function of temperature, showing evidence of a large phonon-drag peak for the 29 nm sample.
Nordheim-Gorter plot (S vs ρ −1) for different NC-Cu samples at 8 K and 300 K.
Parameters such as room temperature resistivity (ρ 300K), electron mean free path (l), product of Fermi wave vector (kF ) and l, Debye temperature (θD ), electron phonon interaction constant (Ae-ph ), and electron phonon interaction at θD (AD ) obtained from the resistivity and fitting of experimental data using equation (2) for different particle sizes.
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