Engineering Graded Magnetic Anisotropy via Cation Interdiffusion in Core/Shell Nanoparticles.

Spinel ferrite nanoparticles (NPs) with controlled composition, size, and morphology have offered a wide range of functional properties, but engineering nonhomogeneous composition profiles remains elusive. Here, we use FeO/CoFeO core/shell NPs as precursors to prepare compositionally graded NPs via controlled interfacial diffusion of metal cations. Electron-microscopy-based elemental mapping reveals that thermal annealing above 200 °C in an oxygen-rich atmosphere transforms the initially sharp core/shell interface into a compositionally graded spinel structure with a Co-rich outer layer.

A Correlative Approach for the Assessment of Porosity in Shale Rocks by Scanning Electron Microscopy.

A correlative approach to compute porosity at the nanoscale in areas as large as 3 mm × 3 mm through field emission scanning electron microscopy (FESEM) is presented. This approach overcomes the limitation of FESEM related to its representativeness on larger areas. The strategy is based on imaging an area of 3 mm × 3 mm where a set of regions of interest (ROIs) of 600 μm × 600 μm with similar mineralogy is selected and imaged.