LAUSR

reducible oxides such as CeO2, the degree of strain can be tuned by different means such as particle size, shape, non-stoichiometry, ambient environment (e.g. oxygen atmosphere, vacuum), structural deformations (e.g. oxygen vacancies) etc. [3]. A critical step in understanding the properties of nanoparticle surfaces is to measure the surface strain on different crystal facets and in the vicinity of surface defects in different ambient environments. We have developed a method to determine the surface strain in oxide nanoparticles with atomic resolution using high resolution transmission electron microscopy (HRTEM). In a typical TEM image, the signal from the heavier Ce atomic columns is much stronger than the signal from the lighter oxygen columns. Consequently, more precise measurements can be made on the cation sublattice in order to map the strain on or near the nanoparticle surface.