Antisite-Defect-Induced Surface Segregation in Ordered NiPt Alloy

Surface and Subsurface Segregation of Co Antisite Atoms in CoAl

In order to minimize the total energy of a disordered alloy crystal, those atoms segregate to the surface, which own the lower surface energy. In ordered systems, this energy gain has to be paid by the energy necessary to create antisite atoms in the bulk and at the surface. In strongly ordering systems, i.e. such with a large formation enthalpy, this energetic balance turns out to be unfavoura...

Segregation-induced ordered superstructures at general grain boundaries in a nickel-bismuth alloy.

The properties of materials change, sometimes catastrophically, as alloying elements and impurities accumulate preferentially at grain boundaries. Studies of bicrystals show that regular atomic patterns often arise as a result of this solute segregation at high-symmetry boundaries, but it is not known whether superstructures exist at general grain boundaries in polycrystals. In bismuth-doped po...

Surface segregation in a polycrystalline Pd70Cu30 alloy hydrogen purification membrane

X-ray photoelectron spectroscopy (XPS) and low energy ion scattering spectroscopy (LEISS) have been used to study the effects of various surface preparations and thermal treatments on the composition of the near-surface region ( 7 atomic layers) and the topmost atomic layer of a polycrystalline Pd70Cu30 alloy. Palladium enrichment (relative to the bulk composition) is observed in the XPS-access...

In situ observation of antisite defect formation during crystal growth.

In situ x-ray diffraction (XRD) coupled with molecular dynamics (MD) simulations have been used to quantify antisite defect trapping during crystallization. Rietveld refinement of the XRD data revealed a marked lattice distortion which involves an a axis expansion and a c axis contraction of the stable C11b phase. The observed lattice response is proportional in magnitude to the growth rate, su...

Identification of an isolated arsenic antisite defect in GaAsBi