Microstructural analysis of obliquely evaporated Co-CoO tape using TEM and EELS

Microstructure of Co-CoO obliquely evaporated tape was studied by energy-filtered electron microscopy combined with high-resolution electron microscopy. Elemental mapping with electron energy-loss spectroscopy revealed that the specimen had a columnar internal structure, in which two types of columns, i.e. Co-rich and O-rich ones, were present. They were identified to be the columns containing mainly Co and CoO, respectively, by image processing of high-resolution electron microscope images. Although the size of Co particles was small, i.e. 5-20 nm, several particles gathered to form clusters within each Co-rich column. The c-axis of the particles inside the cluster was almost parallel to the longitudinal direction of the Co-rich column.