We have studied the electronic structure of nanocrystalline NiO thin films, grown by radio-frequency magnetron sputtering under different experimental conditions, using x-ray absorption spectroscopy. The O 1s and Ni 2p spectra showed distinct changes as a function of O2 content in the plasma, which were reproduced with cluster model calculations. These changes are attributed to the incrementing...

High temperature nanoindentation experiments are conducted to assess the activation enthalpy for deformation of nanocrystalline Ni-W alloys, for grain sizes between 3 and 80 nm. Thermal softening becomes less pronounced at finer grain sizes, and the activation enthalpy has an apparent inflection at a grain size near ~10-20 nm, in the vicinity the Hall-Petch breakdown. This inflection is related...

Biodegradation of citrate occurred under LLW repository relevant conditions with Ni and U present. Citrate biodegradation led to the formation insoluble sulfides or nanocrystalline U( iv )–phosphate may promote Ni/U retention in repositories.

Grain boundary networks should play a dominant role in determining the mechanical properties of nanocrystalline metals. However, these networks are difficult to characterize and their response to deformation is incompletely understood. In this work, we study the grain boundary network of nanocrystalline Ni and explore whether it can be modified by plastic deformation. Mechanical cycling at room...

–The dielectric property of Nanocrystalline nickel is studied. Ni nanocrystal have been synthesized by the thermal decomposition of the Ni (acac)2 [Nickel (acetylacetonate)2], oleylamine complex as a precursor . Trioctylphosphine [CH3(CH2)7]3P was used as both solvent and surfactant for control the size of the nanoparticles. Characterization of the nanoparticles has been done by the XRD and TEM...

Nanocrystalline materials are defined by their fine grain size, but details of the grain boundary character distribution should also be important. Grain boundary character distributions are reported for ball-milled, sputter-deposited, and electrodeposited Ni and Ni-based alloys, all with average grain sizes of ~20 nm, to study the influence of processing route. The two deposited materials had n...

for the first time this study reported the success of using nanocrystalline hexagonal close-packed (hcp) nickel (ni) modified composite graphite (cg) electrode (hcp-nano ni/cg) for the electrocatalytic oxidation of glycerol in alkaline medium (0.1 m koh). the hcp-nano ni/cg electrode had an improve response and specificity on the electrocatalytic oxidation of glycerol over the bare cg. the elec...

We demonstrate cyclic strain hardening and frequency-dependent fatigue life in electrodeposited nanocrystalline Ni subjected to tension–tension cyclic deformation. These observations are rationalized through mechanistic arguments based on the exhaustion of dislocation sources in the early stages of cyclic loading and on the domination of diffusive processes during later stages. 2005 Acta Materi...

A long-standing controversy exists between molecular dynamics simulations and experiments on the twinning propensity of nanocrystalline (NC) face-centered-cubic metals. For example, three-dimensional molecular dynamics simulations rarely observed twins in NC Ni, whereas experiments readily observed them. Here this discrepancy is resolved by experimental observation of an inverse grain-size effe...