Phonon confinement in ultrathin nickel films

Melikyan, A. O.; Minassian, H.

doi:10.1016/s0009-2614(00)01161-1

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…13 Phonon confinement affects all phonon relaxation rates and should affect thermoelectric transport as in electrical transport, wherein grain boundary ͑GB͒ disorder prevails. 2,14 We have investigated thermopower S n of compacted 38, 32, and 25 nm nanocrystalline nickel ͑n-Ni͒ as one can obtain oxygen-free compacted pellets. 2 As D decreases, there is a considerable decrease in ͉S n ͉, gradual disappearance of phonon drag minimum ͑PDM͒, and anomalous sign changes to positive at low temperature T ͑below 38 K͒ compared to S bulk .…”

Section: Size-dependent Thermopower In Nanocrystalline Nickelmentioning

confidence: 99%

Size-dependent thermopower in nanocrystalline nickel

Soni

Okram

2009

Applied Physics Letters

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Thermopower (Sn) of compacted nanocrystalline Ni of average particle size D=38, 32, and 25 nm at low temperatures (5–300 K) is reported here. Sn exhibits striking deviations from bulk thermopower Sbulk behavior revealing evolution of Sn with change in D. As D decreases, there is significant decrease in Sn, gradual disappearance of phonon drag minimum and sign change to positive below 38 K compared to usual negative Sbulk. They have been attributed to electron and phonon scattering at grain boundaries and phonon confinement. Small minima observed near 25 K in thermopower difference ΔS are correlated with superparamagnetic transitions.

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Section: Size-dependent Thermopower In Nanocrystalline Nickelmentioning

confidence: 99%

Size-dependent thermopower in nanocrystalline nickel

Soni

Okram

2009

Applied Physics Letters

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“…where P bulk e−p is the scattering probability in the bulk [32]. With a sound velocity of 3 × 10 3 m s −1 , NW diameter of 30 nm and temperature of 10 K, the exponent exceeds 1 by several orders of magnitude, and therefore considerably decreases the scattering probability as compared with that of the bulk.…”

Section: Initial Characterization Of the Measurement Devicementioning

confidence: 99%

Thermopower measurements on individual 30 nm nickel nanowires

2007

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The thermopower of individual, 30 nm in diameter, Ni nanowires is measured as a function of bath temperature in the range 4–300 K. Boundary scattering of phonons at low temperatures (<50 K) inhibits any phonon drag effect, that in contrast is observed for bulk Ni. In the diffusion regime (>50 K) the absolute values of the thermopower are found to be smaller than the bulk values. This finding can be explained semi-quantitatively by considering electron scattering at grain boundaries. Any interpretation of size dependent thermopower in nanoscale ferromagnetic materials needs to explicitly consider the above effects.

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“…With nanoparticles as quantum wells, phonon dispersion and group velocities change due to spatial confinement induced by GBs [25]. Phonon confinement affects all phonon relaxation rates and should affect thermoelectric transport as in electrical transport, wherein GB disorder prevails [18,26,27].…”

Section: Introductionmentioning

confidence: 99%

“…Fascinating aspects of nanostructures in this regard are spatial confinement of carriers and corresponding change in carrier density of states [18,25,26]. With nanoparticles as quantum wells, phonon dispersion and group velocities change due to spatial confinement induced by GBs [25].…”

Section: Introductionmentioning

confidence: 99%

Influence of surfactants on the electrical resistivity and thermopower of Ni nanoparticles

Kaurav¹,

Okram

Ganesan

2014

Mater. Res. Express

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Compacted pellets of nanocrystalline nickel (NC-Ni) of average particle size ranging from 18 to 33 nm were prepared using a variety of surfactants. They were characterized well and were studied on the influence of the surfactants on the electrical resistivity and thermopower in the temperature range 5 to 300 K. It was found that the type of the surfactant used dominates over the average particle size in their electrical transport and the detail transport behaviors have been discussed. Moreover, the observed thermopower and resistivity features were contrasting compared to what are normally seen in the well-known materials.They are interpreted as indicative of attractive features these surfactants for the design of nanostructured thermoelectric materials with enhanced thermoelectric figure of merits.

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Phonon confinement in ultrathin nickel films

Cited by 10 publications

References 15 publications

Size-dependent thermopower in nanocrystalline nickel

Size-dependent thermopower in nanocrystalline nickel

Thermopower measurements on individual 30 nm nickel nanowires

Influence of surfactants on the electrical resistivity and thermopower of Ni nanoparticles

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