Controlling morphology and texture of sputter-deposited Pd films by tuning the surface topography of the (Ti) adhesive layer

Neha Verma*, Giridharan Krishnamurthy, Frans D. Tichelaar, Amarante J. Böttger

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    2 Citations (Scopus)

    Abstract

    In this work, the effect of the deposition parameters of a magnetron sputtered Ti adhesive intermediate layer on the morphology and hydrogen absorption properties of thin Pd films of about 100 nm was investigated. The insertion of an adhesive layer between a Pd film and a rigid substrate usually suppresses or reduces hydrogen absorption. In this study, it is shown that by tuning the surface topography of the intermediate layer the morphology, crystallographic texture and hydrogen absorption properties of the Pd film can be controlled. The surface topography of the Ti layer was characterized using atomic force microscopy. The surface topography strongly depends on the Ti deposition conditions and can vary from widely spread large islands to densely packed small-grained islands depending on thickness (between 1 and 6 nm) and sputter pressure (0.4 and 3 Pa). TEM and XRD analysis led to the conclusion that rough Ti intermediate layers result in Pd films with an open columnar structure with small voids, and a weak and broad (111) texture. Smooth Ti intermediate layers promote the formation of Pd films with a dense columnar structure with fewer voids, and a strong and sharp (111) texture. Changes in the Pd adatom surface diffusion and shadowing effects are the main cause of the observed differences. Pd films with an open columnar morphology and weaker texture show better hydrogen absorption properties with respect to absorption capacity and kinetics of the films with dense columnar morphology. By tuning the surface topography of the Ti adhesive layer, Pd films with controlled morphology and texture can be prepared such that no delamination from the substrate occurs without compromising on absorption properties.

    Original languageEnglish
    Pages (from-to)24-34
    JournalSurface and Coatings Technology
    Volume359
    DOIs
    Publication statusPublished - 2019

    Keywords

    • Adhesive layer
    • Film morphology
    • Hydrogen absorption
    • Kinetics
    • Surface topography
    • Texture

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