Direct subangstrom measurement of surfaces of oxide particles

Using aberration-corrected transmission electron microscopy combined with first-principles calculations, we show that the surface structure of Co ₃O₄, a typical complex oxide, can be directly imaged and quantitatively analyzed at the subangstrom scale. The atomic positions of both light oxygen and heavier cobalt within the surface layers have been measured to an accuracy of several picometers. The surface electronic structure analysis suggests a polarity compensation model based on the electronic polarizability of surface ions.