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Author Abadias, G. ♦ Debelle, A. ♦ Michel, A. ♦ Jaouen, C. ♦ Martin, F. ♦ Pacaud, J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ ARGON IONS ♦ ATOMIC DISPLACEMENTS ♦ CRYSTAL STRUCTURE ♦ ELASTICITY ♦ EPITAXY ♦ INTERFACES ♦ ION BEAMS ♦ ION IMPLANTATION ♦ IRRADIATION ♦ LATTICE PARAMETERS ♦ LAYERS ♦ MOLYBDENUM ♦ NICKEL ♦ SHOT PEENING ♦ SPUTTERING ♦ STRAINS ♦ STRESSES ♦ SUPERLATTICES ♦ THIN FILMS ♦ X-RAY DIFFRACTION ♦ BEAMS ♦ CHARGED PARTICLES ♦ COHERENT SCATTERING ♦ COLD WORKING ♦ CRYSTAL GROWTH METHODS ♦ DIFFRACTION ♦ ELEMENTS ♦ FABRICATION ♦ FILMS ♦ IONS ♦ MATERIALS WORKING ♦ MECHANICAL PROPERTIES ♦ METALS ♦ PHYSICAL RADIATION EFFECTS ♦ RADIATION EFFECTS ♦ REFRACTORY METALS ♦ SCATTERING ♦ SURFACE TREATMENTS ♦ TRANSITION ELEMENTS
Abstract The present study deals with the analysis of elastic strains and stresses in high-quality heteroepitaxial Mo/Ni superlattices with periods {Lambda} lying in the range 4.8-27.6 nm. The strain-stress state in this lattice-mismatched system grown under energetic deposition conditions (ion beam sputtering) is rather complex, resulting from three contributions: (i) intrinsic (growth) stress due to atomic peening, (ii) coherency stresses of opposite sign in the two elemental layers due to the observed Nishiyama-Wassermann epitaxial relationship Ni[110](111)||Mo[001](110), and (iii) interfacial mixing. The measurement of the lattice parameters of Mo and Ni sublayers in various crystallographic directions was performed by x-ray diffraction, using the sin{sup 2} {psi} method adapted for epitaxial layers. A large anisotropy of elastic strain and associated in-plane coherency stresses is revealed in the Mo sublayers, while for Ni sublayers no such behavior could be detected due to the superimposition of growth variants with threefold symmetry. Postgrowth ion irradiation with Ar ions at very low dose ({approx}0.2 dpa) was employed as a powerful tool to modify the intrinsic stress, thus providing additional data to be implemented in a triaxial strain-stress model, which enabled us to separate the different stress sources (intrinsic and coherency stresses) as well as to quantify the intermixing occurring during growth. This model, which has been successfully applied previously to Mo thin films, yields in the case of multilayer systems to the determination of the ''stress-free and defect-free'' lattice parameter, a{sub 0}, i.e., solely linked to chemical mixing. The linear dependence of a{sub 0} with {Lambda} observed in both sublayers reveals an interface-mediated chemical mixing mechanism, the extent of this interfacial mixing being much more pronounced in Mo sublayers than in Ni ones.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2010-01-15
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 107
Issue Number 2


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