Asymmetric alloy formation at the Fe-on-Ti and Ti-on-Fe interfaces

Abstract

The Fe-on-Ti and Ti-on-Fe interfaces were studied experimentally by Mössbauer spectroscopy (MS), transmission electron microscopy (TEM) and x-ray reflectometry (XRR) on Ti/Fe/Ti trilayers grown on Si(1 1 1) substrates by vacuum evaporation. The nanoscale structure and composition were explored in cross sections using TEM, the layer structure and the interface widths by specular x-ray reflectometry. MS was applied to identify the interface alloy phases and to determine the pure and alloyed Fe layer fractions. The experimental results were compared with molecular dynamics (MD) simulations of layer growth on Fe or Ti underlayers of different orientations. The concentration distributions provided by MD simulations show an asymmetry at the interfaces in the layer growth direction. The transition is atomically sharp at the Ti-on-Fe interface for the (0 0 1) and (1 1 0) crystallographic orientations of the Fe underlayer, while it spreads over a few atomic layers for Fe(1 1 1) underlayer and for all studied Ti underlayer orientations at the Fe-on-Ti interface. MS and XRR data on Ti/Fe/Ti trilayers confirm the asymmetry between the bottom and top Fe interface, but the inferred interface widths considerable exceed those deduced from the MD simulations.

Hybridization of 2D MoS2 Nanoplatelets and PtAu Hybrid Nanoparticles for the SERS Enhancement of Methylene Blue

“…Meanwhile, the background NPs were much larger as shown in the atomic force microscopy (AFM) top-views in Figure 3a-d, which is a typical characteristic of SSD. [18,27] As seen in Figure 3a-1-d-1, the core-shell PtAu NPs all showed a comparable average height of ≈40 nm. Similarly, the background Au NPs were gradually developed and reached more than 20 nm in height at 800 °C.…”

Study of Interfaces in Hf/Fe System Using Magneto‐Optical Kerr Effect and Soft X‐Ray Absorption Spectroscopy

“…Such an asymmetry in the interfacial intermixing is observed quite often in metallic multilayers. [35][36][37][38] The factors responsible for such asymmetry include thermodynamic factors such as surface-free energies and/or cohesive energies, [35,36,38] or ballistic effects. [39] One may note that the total thickness of the Fe layer intermixed with Hf at both the interfaces is 0.45 nm.…”