Experimental and theoretical studies of the dislocation structure of NiO-Pt interfaces

Abstract

The dislocation structure of (001) NiO-Pt interfaces was studied using electron microscopy and electron diffraction techniques. Specimens were produced by hot pressing polycrystalline Pt films on to thin NiO single crystals, and bulk Pt single crystlas on to bulk NiO single crystals. The polycrystalline Pt specimens were used to determine the favored orientation relationships between the (001) NiO and Pt, while the bulk NiO-Pt specimens were used to study the detailed structur of interface. Three categories of orientation relationships were identified: exact epitaxy with (001) pt∥ (001) NiO, [110] Pt ∥ [110] NiO; small rotations away from exact epitaxy about the common [001] direction, and high index planes of Pt parallel to (001) of NiO. Theoretical calculations of the expected dislocation structures of interfaces with the first two orientation relationships, as well as others which are small perturbations away from these two, were made using a Bollmann-type analysis. The experimental observations and theoretical predictions were shown to be in generally good agreement, with some differences with respect to the detailed structure. The energies of the interfaces having the first two orientation relationships were shown to be similar which is believed to be the reason why they both occur.