Recent experimental and theoretical studies have shown an essential role of sulfur segregationinduced amorphization of crystalline nickel leading to its embrittlement at a critical sulfur concentration of 14%, but the atomistic mechanism of the amorphization remains unexplained. Here, molecular dynamics simulations reveal that the large steric size of sulfur impurity causes strong sulfur-sulfur...

The kinetics of hydrogen absorption by Pd(ll0) have been measured as a function of impurity sulfur coverage on the metal surface. In contrast to results obtained on the clean surface in which the absorption process was found to be rate-limited by the diffusion of atomic hydrogen into the bulk, submonolayer coverages of sulfur cause the kinetics to become surface dominated with the dissociative ...

We report the electronic properties of two-dimensional systems made of graphene nanoribbons, which are patterned with ad-atoms in two separated regions. Due to the extra electronic confinement induced by the presence of impurities, we find resonant levels, quasi-bound and impurity-induced localized states, which determine the transport properties of the system. Regardless of the ad-atom distrib...

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The exceptional properties of nanocrystalline materials lend themselves to a wide range of structural and functional applications. There is recent evidence to suggest that grain boundary impurities may have a dramatic effect on the stability, strength and ductility of nanocrystalline metals and alloys. In this study, transmission electron microscopy and atom probe tomography were used to charac...

Barium fluoride is an example of a high-density scintillator for detecting high-energy radiation. In use, its luminescent transmission is seriously degraded by radiation damage. This effect is associated with oxygen, among other impurities. At one time it was suspected that oxygen O, having been dissociated from a defect complex by radiation damage, absorbed some of the luminescent energy of th...

We study an Anderson impurity in a semiconducting host using the density matrix renormalization group technique. We use the U = 0 one–dimensional Anderson Hamiltonian at half filling as the semiconducting host since it has a hybridization gap. By varying the hybridization of the host, we can control the size of the semiconducting gap. We consider chains with 25 sites and we place the Anderson i...

This paper presents an analysis of the motion of an neutral impurity species in a nanometer scale 4He cluster, extending a previous study of the dynamics of an ionic impurity. It is shown that for realistic neutral impurity–He potentials, such as those of SF6 and OCS, the impurity is kept well away of the the surface of the cluster by long range induction and dispersion interactions with He, bu...

This paper presents an analysis of the motion of an neutral impurity species in a nanometer scale 4He cluster, extending a previous study of the dynamics of an ionic impurity. It is shown that for realistic neutral impurity–He potentials, such as those of SF6 and OCS, the impurity is kept well away of the the surface of the cluster by long range induction and dispersion interactions with He, bu...

This paper presents an analysis of the motion of a neutral impurity species in a nanometre scale He cluster, extending a previous study of the dynamics of an ionic impurity. It is shown that for realistic neutral impurity± He potentials, such as those of SF6 and OCS, the impurity is kept well away from the surface of the cluster by long range induction and dispersion interactions with He, but t...