Quantitative size-factors for metallic solid solutions

King, H. W.

doi:10.1007/bf00549722

Cited by 785 publications

(252 citation statements)

References 12 publications

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“…3. The values deviate from Vegard's law but are in general agreement with those obtained from vapor quenched samples 13 and for metastable solid-solution samples prepared by mechanical attrition. 7 When higher annealing temperatures ͑TϾ250-300°C͒, are employed, two sets of fcc XRD peaks are observed.…”

supporting

confidence: 84%

Inversion of surface composition and evolution of nanostructure in Cu/Co nanocrystals

Edelstein

Harris

Rolison

et al. 1999

Applied Physics Letters

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Nanocrystals of Cu/Co with a nearly pure Cu core and a Co-rich shell have been chemically synthesized. This structure results from reaction kinetics and represents an inversion of surface composition since the surface energy of Co is larger than that of Cu. Both the Cu core and the Co-rich shell initially have an fcc structure and a common lattice constant. Annealing at temperatures in the range of 300 to 600°C causes the material to phase separate, forming small, increasingly pure Co nanocrystals which aggregate on the surface of the pure Cu nanocrystals. © 1999 American Institute of Physics. ͓S0003-6951͑99͒02621-2͔The Cu/Co system, which has no intermetallic compounds and limited mutual solubility, has been studied extensively. 1,2 Despite the limited solubility, metastable solid solutions have been prepared by rapid quenching, 2,3 sputtering, 4,5 and mechanical attrition. 6,7 Giant magnetoresistance in granular systems was first observed 5,8 in phaseseparated, sputtered films of Cu 8 Co 2 .Here we report the chemical synthesis of nanocrystalline Cu 80 Co 20 with an unusual structure. The nanocrystals have a nearly pure Cu face-centered-cubic ͑fcc͒ core and a Co-rich outer fcc shell with the same lattice constant as the Cu core. This result is surprising because the surface energy 9 of Cu, 1.934 J m Ϫ2 , being smaller than that of Co, 2.709 J m Ϫ2 , affects the morphology of Cu/Co bilayers. For example, a 380 K anneal of a thin Co film deposited on Cu causes Cu atoms to diffuse through pinholes onto the Co surface. 10 Our surface composition inversion is a result of reaction kinetics.Annealing causes the material to phase separate, forming smaller, increasingly pure, Co nanocrystals which form on the surface of the larger, pure Cu nanocrystals. A potentially useful property of the material is that because the Co oxidizes preferentially, the oxidation of the Cu is significantly delayed. 11 The polyol process is another chemical route that has been used 12 to investigate nanocrystalline Cu/Co, but no evidence was found for the structural evolution reported here.Our material is prepared by first precipitating a hydroxide from solutions of either metallic chlorides or nitrates. The hydroxide is converted first to an oxide and then reduced to metallic form ͑flowing hydrogen at 205-215°C for 15 min͒. Heat treatments at higher temperatures and longer times cause complete phase separation and increase the particle size. The different stages of the structural evolution are illustrated in Fig. 1. It is important that one or both of the precursors, the hydroxide and/or the oxide, contains a mixture of Cu and Co. If not, then reduction leads directly to phase separation. When we apply a similar procedure to the Cu/Fe system, a metastable solid solution is not formed ͑pre-sumably because Cu and Fe do not form mixed metal precursors͒. In the following, we present experimental evidence supporting the structural and morphological evolution described above.X-ray photoelectron ͑XPS͒ and energy-dispersive x-ray ͑EDXS͒ spectrosco...

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supporting

confidence: 84%

Inversion of surface composition and evolution of nanostructure in Cu/Co nanocrystals

Edelstein

Harris

Rolison

et al. 1999

Applied Physics Letters

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“…This shift in lattice parameter is characteristic of substitutional solid-solutions, where the lattice parameter must change in order to accommodate for strain that arises due to the differing atomic sizes of the constituent atoms as well as attractive and repulsive forces between the guest and host metal atoms. 60,61 From the HRTEM, EDX mapping, X-ray and electron diffraction data, we propose that the products of the decomposition reaction are single-crystal nanoparticles consisting of a substitutional solid-solution of nickel and iron in rocksalt crystal structure. As short hand, we refer to this phase as [Ni,Fe]O, a nonequilibrium phase under ambient conditions.…”

Section: Chemistry Of Materialsmentioning

confidence: 99%

Nickel/Iron Oxide Nanocrystals with a Nonequilibrium Phase: Controlling Size, Shape, and Composition

Bau

Marenco

et al. 2014

Chem. Mater.

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/npsi/ctrl?action=rtdoc&an=21272906&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21272906&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

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“…This ignorance of the coppervacancy binding may change the damage rate dependence. The volume size factor of a copper atom in an iron matrix is reported by +17.55%, 8) so copper atoms tend to bind with vacancies. As the copper-vacancy pair is the dominant mechanism in the migration of copper atoms, the incorporation of copper-vacancy binding is necessary for improvement of the calculation model.…”

Section: Introductionmentioning

confidence: 99%

Model Calculation of the Damage Rate Dependence of Yield Stress Change in an Irradiated Fe-Cu Model Alloy

Yanagita

Yoshiie

et al. 2002

Mater. Trans.

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The damage rate dependence of the yield stress change in a neutron-irradiated Fe-Cu model alloy was analyzed by a model calculation. The model was based on the rate theory, and focused on the description of the nucleation and growth of point defect clusters and copper clusters. The binding between copper atoms and vacancies and the effect of cascade damage which directly creates small point defect clusters were incorporated in this model. The instability of small point defect clusters caused by thermal dissociation was also included. From the result of the calculation, the yield stress changes were estimated using the Orowan model and the Russel-Brown model. As a result of this calculation, it was clarified that copper clusters are the main factor of yield stress change in almost all irradiation stages below 0.1 dpa. The contribution of copper clusters to yield stress change increased with decreasing damage rate. The nature of the damage rate dependence is not affected by the copper-vacancy binding but by the sink strength, which changes dynamically throughout irradiation.

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Quantitative size-factors for metallic solid solutions

Cited by 785 publications

References 12 publications

Inversion of surface composition and evolution of nanostructure in Cu/Co nanocrystals

Inversion of surface composition and evolution of nanostructure in Cu/Co nanocrystals

Nickel/Iron Oxide Nanocrystals with a Nonequilibrium Phase: Controlling Size, Shape, and Composition

Model Calculation of the Damage Rate Dependence of Yield Stress Change in an Irradiated Fe-Cu Model Alloy

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