Nanocrystalline orientation and phase mapping of textured coatings revealed by precession electron diffraction

Nanocrystalline orientation and phase mapping were performed to characterize texture and grain boundary tilt angles in the transmission electron microscope (TEM) using precession electron diffraction (PED). Texture analysis and grain boundary angle studies were performed on atomic layer deposition (ALD) ZnO/Al2O3/ZrO2 nanolaminate coatings. It was determined that the ZnO layer nanocolumnar grains, with random rotational orientation, exhibited fiber texture with predominately <0001> grains in the out-of-plane direction with respect to the substrate. The ZnO tilt angles were in the range of 10–20° signifying a large area fraction of predominately low angle grain boundaries. The nanolaminate coating has been shown to mitigate tribological (energetic) losses by decreasing friction and wear during sliding, hence is a potential solid lubricant material. The TEM-PED technique has future wide scale applicability in studying energy-related nanomaterial grain orientations and phases with a spatial resolution down to 1–2 nm, in which more traditional techniques, such as electron-backscatter diffraction, cannot resolve.