Wayne D. Kaplan, Solid-solid interface reconstruction at nominally incoherent interfaces: Ni-Al2O3 and Ni-YSZ

Hadar Nahor, Hila Meltzman, and Wayne D. Kaplan

Department of Materials Science and Engineering, Technion – Israel Institute of Technology, Technion City, Haifa 32000, Israel

Atomistic characterization of interfaces usually focuses on low-index orientations where semicoherent interfaces can be described using misfit dislocations separating regions of coherency. However, many systems are incoherent due to significant differences in lattice symmetry and/or lattice parameters. Mechanisms for strain compensation at incoherent interfaces have been largely ignored. In this presentation the structure of equilibrated Ni-sapphire and Ni-YSZ interfaces will be presented. Equilibrated Ni particles were formed by solid-state dewetting of Ni films on the substrates. Aberration corrected scanning transmission electron microscopy (S/TEM) showed that the Ni-sapphire(0001) interface is incoherent, and reconstructs to form a 2.5√3R30 2-D lattice. The more than 30% mismatch between Ni and YSZ leads to a nominally incoherent interface, containing a high density of semi-periodic misfit dislocations which define the reconstructed interface. The concept of interfacial reconstruction as mechanism for compensating strain energy will be discussed.

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