Electrical transport properties of nanocrystalline nickel

Solution phase synthesized Ni nanoparticles(NPs) of Scherrer size 20.5 ± 0.9 nm are characterized systematically using X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Their electrical transport properties in temperature range 5 K to 300 K are studied using electrical resistivity (ρ) & Seebeck coefficient (S). The ρ and the strength of electron-phonon interaction (αe-ph) are increased while residual resistance ratio (RRR) & Debye temperature (θD) decreased in NPs compared to bulk Ni. Furthermore, an unusual crossover from negative to positive S, and suppression and shift at higher temperature in phonon drag feature for NPs compared to bulk are observed. These results are mainly attributed to confinement of electrons and phonons and their enhanced scattering from grain boundaries and other defects.