Ion Beam Mixing Effects in Au-Fe and Pt-Fe Thin Bilayers
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ION BEAM MIXING EFFECTS IN Au-Fe AND Pt-Fe THIN BILAYERS
G. BATTAGLIN"', A. CARNERAX, G. CELOTTI:C, G. DELLA MEA-:, V.N. KULKARNIJ:, S. LO RUSSO:- AND P. MAZZOLDI:: :UnitA GNSM-CNR, Dipartimento di Fisica dell'Universita, Via Marzolo 8, 35131 Padova, Italy; Istituto CNR-La.M.El., Via Castagnoli 1, 40126 Bologna, Italy
ABSTRACT ++
Mixing effects induced by Kr bombardment in the Au-Fe and Pt-Fe metallic systems have been studied by Rutherford backscattering and X-ray diffraction techniques. The mixed amount of Fe atoms shows a linear dependence on the square root of the Kr do se for both systems. The induced mixing appears more efficient for the Pt-Fe with respect to the Au-Fe system. In the case of Pt-Fe mixing is much more efficient when the initial bilayer structure has Pt on the top. The X-ray diffraction analysis re veals the formation of an extended solid solution of Fe in Pt, having the Fe 4 0 Pt 6 0 composition.
INTRODUCTION Ion mixing is a choice method in forming metastable materials with either crystalline or non-crystalline structure [1-4]. Cascade mixing and radiation enhanced diffusion are substantial in the formation of metastable phases, equilibrium compounds or solid solutions. Ion mixing appears not only a powerful technique for production of specialized alloy surfaces but is also attractive in studying the mechanisms involved in the irradiation process. In the present paper we report an investigation of the intermixing effects induced by Kr++ bombardment on the Pt-Fe and Au-Fe metallic systems.
EXPERIMENTAL The Au-Fe, Pt-Fe (Fe on top in both cases) and Fe-Pt (Pt on top) bilayer structures were prepared by sequential e-beam vacuum (^10-6 torr) evaporation of the two respective metals onto Si single crystals or glass plates of 50 mm x 25 mm x 2 mm dimension. In the second situation the element on the top (Fe) was deposited onto a tilted glass plate to produce a surface layer of varying thickness. The thick nesses for the different deposited layers ranged from 100 A to 500 A. The samples were bombarded at room temperature with Kr++ ions of 100 to 200 keV energy at doses ranging from I x 1015 to 3.5x1016 ions/cm2. The beam 2 current density was maintained at a value of 0.5 OA/cm2 in order to avoid
SWork
supported by- Consiglio Nazionale delle Ricerche, to Metallurgia.
Progetto Finalizza-
Hat. Rea. Soc. Symp. Proc. Vol. 27 (1984)QElsevier Science Publishing Co., Inc.
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heating effects. The samples were analyzed by Rutherford backscattering spectrometry (RBS) using a 1.8 MeV 4He+ beam.Glancing angle X-ray diffraction (XRD) was employed to identify the phases produced by the bombardment. The surface mor phology was investigated by Scanning Electron Microscopy (SEM).
RESULTS AND DISCUSSION The scanning electron microscopic measurements revealed that the surface of the samples is flat before and after bombardment in all the cases. Therefore the backscattering spectra are free from the artifacts which would arise because of a surface structure having globules or some other inhomogeneities. Fig
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