Anomalous Isotope Effect in Metallic Diffusion

Lazarus, D.; Okkerse, B.

doi:10.1103/physrev.105.1677

Cited by 14 publications

(1 citation statement)

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“…A correction was made to the diffusion constants for lattice expansion, but no allowailce was made for an isotopic mass effect. Johnson's (10) original worli, which suggested that Graham's law applied to metallic diffusion as well as to gaseous diffusion, has not been substantiated by more recent work (11). For personal use only.…”

Section: Resultsmentioning

confidence: 99%

Self-Diffusion in Polycrystalline Nickel

MacEwan¹,

MacEwan²,

Yaffe³

1959

Can. J. Chem.

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The self-diffusion of nickel has been studied in polycrystalline sanlples by a sectiorling technique. There is evidence of grain boundary diffusion below temperatures of 1150" C. The results obtained between 1150' and 1400" C are representative of volume diffusion and are represented by the expression D = 3.36 e-69.8001RT.A conlparison is made with the results of other self-diffusion studies using Zener's hypothesis. INTRODUCTIONThe most precise measurements made on the rate of volume self-diffusion in metals have been carried out with single crystal specimens. Measurements made with polycrystalline specimens have been in good agreement with those made with single crystal specimens only when the diffusion study was confined to temperatures close to the melting point of the metal. None of the reported investigations (1, 2, 3) made of the self-diffusion of nickel in polycrystalli~~e samples have satisfied this criterion. Therefore, it was thought worth while to report some worlc on the rate of nickel self-diffusion in the temperature range 1050' to 1400' C. E X P E R I M E N T A L Diffusion coefficients were obtained by the standard sectioning method (4) and by a modification of Gruzin's integral residue method (5). In some cases both techniques were en~ployed to analyze the same specimen, which permitted a direct coinparison of the results obtained with each.The nickel tracer employed contained two long-lived isotopes, Ni63 decaying with the emission of a 67-kev p-particle and Ni5Vecaying by K-electron capture with the emission of a Co K, X-ray (6). A Coj8, gamma-emitting impurity present in the tracer solution was completely removed by an ion exchange procedure (7). In the 27r internal source proportional counter employed, the ratio of detected disintegrations of Nim to Ni59 was in excess of 5x103 for almost all sources counted. Thus, with one exception which will be discussed later, it was assumed that the tracer consisted of a single active species, Ni63.The diffusion specimens consisted of polycrystalline nickel cylinders about 0.60 in. in diameter with the active tracer electroplated on one face. The total analyzed impurity

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Section: Resultsmentioning

confidence: 99%