Cobalt silicide formation on a Si(1 0 0) substrate in the presence of an interfacial (Fe90Zr10) interlayer

The reaction between a thin film (126 nm) of Co and Si has been studied at 450 C for 24 h under high vacuum conditions, in the presence of a FeZr barrier layer. Without a diffusion barrier layer between Co and Si, Co2Si forms at 350 C as the initial phase while CoSi2 forms at 550 C. The FeZr barrier layer changed the flux of atoms arriving at the reaction interface. Co reacted with the Si from the substrate and formed a mixed layer of CoSi and CoSi2 in the interlayer region. The use of the FeZr diffusion barrier has been demonstrated to lower the temperature formation of CoSi2 to 450 C. The reactions were characterised by Rutherford backscattering spectrometry, Auger electron spectroscopy depth profiling, X-ray diffraction using CoKa radiation and scanning electron microscopy.http://www.elsevier.com/locate/nimb2016-09-30hb201

C-language package for standalone embedded atom method molecular dynamics simulations of fcc structures

AbstractAb-initio molecular dynamics (MD) employs Newtonian mechanics to model and simulate the time evolution of particle trajectories in material science ensembles using a differentiable potential function. Although commercial and free packages exist for MD, their heuristic nature prevents dissection. This open-source C-language package arose out of the interest to study effects of embedded atoms in metallic face-centered cubic structures (fcc) on a standalone computer. The algorithms use velocity–time integration to output instantaneous particle parameters for up to several thousands of particles in the NVT ensemble. The functions are coded in a reusable and redistributable standalone header library file

Microstructure engineering of Pt-Al alloy thin films through Monte Carlo simulations

A kinetic algorithm, based on the regular solution model, was used in conjunction with the Monte Carlo method to simulate the evolution of a micro-scaled thin film system during exposure to a high temperature environment. Pt-Al thin films were prepared via electron beam physical vapor deposition (EB-PVD) with an atomic concentration ratio of Pt63:Al37. These films were heat treated at an annealing temperature of 400 °C for 16 and 49 minutes. Scanning Auger Microscopy (SAM) (PHI 700) was used to obtain elemental maps while sputtering through the thin films. Simulations were run for the same annealing temperatures and thin-film composition. From these simulations theoretical depth profiles and simulated microstructures were obtained. These were compared to the experimentally measured depth profiles and elemental maps

Origin of the red emission in zinc oxide nanophosphors

UV andorange-redlightemittingzincoxidenano-phosphors(ZnONPr)weresynthesisedbya combustion methodusingzincnitrateandzincacetateasprecursorsandureaasafuel.Hexagonal wurtzite structuresofZnOweresynthesised.X-rayphotoelectronspectroscopy(XPS)indicatedthatthe O1s peakconsistofthreecomponents:O1(ZnO),O2(deficient oxygen;OHgroups)andO3(adsorbed species) centredat530.3,531.2and532.6eV,respectively.Abroadorange-redemissionfrom500to 850 nmwasobtainedfromtheZnONPrpreparedwiththenitrateprecursorwhichmaybeattributedto different kindsofdefects,andasharpUVband,duetothepossiblepassivationofdefects,at392nmfrom ZnO NPrpreparedwithacetateprecursor.WethanktheSouthAfricanNationalResearchFoundationand UFS for financial support.AuthorsarealsothankfultoDr.Mukut Ghoain, DepartmentofChemistry,UFSforfruitfulscientific discussion.UV andorange-redlightemittingzincoxidenano-phosphors(ZnONPr)weresynthesisedbya combustion methodusingzincnitrateandzincacetateasprecursorsandureaasafuel.Hexagonal wurtzite structuresofZnOweresynthesised.X-rayphotoelectronspectroscopy(XPS)indicatedthatthe O1s peakconsistofthreecomponents:O1(ZnO),O2(deficient oxygen;OHgroups)andO3(adsorbed species) centredat530.3,531.2and532.6eV,respectively.Abroadorange-redemissionfrom500to 850 nmwasobtainedfromtheZnONPrpreparedwiththenitrateprecursorwhichmaybeattributedto different kindsofdefects,andasharpUVband,duetothepossiblepassivationofdefects,at392nmfrom ZnO NPrpreparedwithacetateprecursor