Epitaxial growth of Al9Ir2 intermetallic compound on Al(100): Mechanism and interface structure

J. Kadok (1) , K. Pussi (2) , S. Šturm (3) , B. Ambrožič (3) , É. Gaudry (1, 3) , M.-C. de Weerd (1, 3) , V. Fournée (1, 3) , J. Ledieu (1, 3)

1 IJL - Institut Jean Lamour
2 Lappeenranta University of Technology
3 IJS - Jozef Stefan Institute [Ljubljana]

The adsorption of Ir adatoms on Al(100) has been investigated under various exposures and temperature conditions. The experimental and theoretical results reveal a diffusion of Ir adatoms within the Al(100) surface selvedge already at 300 K. Above 593 K, two domains of a (√ 5× √ 5)R26.6 • phase are identified by low energy electron diffraction (LEED) and scanning tunneling microscopy measurements. This phase corresponds to the initial growth of an Al 9 Ir 2 compound at the Al(100) surface. The Al 9 Ir 2 intermetallic domains are terminated by bulklike pure Al layers. The structural stability of Al 9 Ir 2 (001) grown on Al(100) has been analyzed by density functional theory based calculations. Dynamical LEED analysis is consistent with an Ir adsorption leading to the growth of an Al 9 Ir 2 intermetallic compound. We propose that the epitaxial relationship Al 9 Ir 2 (001)Al(100) and Al 9 Ir 2 [100]Al[031]/[013] originates from a matching of Al atomic arrangements present both on Al(100) and on pure Al(001) layers present in the Al 9 Ir 2 compound. Finally, the interface between Al 9 Ir 2 precipitates and the Al matrix has been characterized by transmission electron microscopy measurements. The cross-sectional observations are consistent with the formation of Al 9 Ir 2 (001) compounds. These measurements indicate an important Ir diffusion within Al(100) near the surface region. The coherent interface between Al 9 Ir 2 and the Al matrix is sharp.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Matériaux

J. Kadok, K. Pussi, S. Šturm, B. Ambrožič, É. Gaudry, et al.. Epitaxial growth of Al9Ir2 intermetallic compound on Al(100): Mechanism and interface structure. Physical Review Materials, 2018, 2 (4), pp.43405 - 43405. ⟨10.1103/PhysRevMaterials.2.043405⟩. ⟨hal-01784977⟩