Distinguishing Nb and O atoms in lithium-niobium oxide with 200 kV electron microscope

An image of Li_(1-x)NbO_2(x≈0.7) taken far from the Scherzer focus condition with a 200 kV electron microscope has been transformed into the structure image by performing the image deconvolution.The atomic columns of Nb and O at a distance of 0.153 nm are resolved clearly in the deconvoluted images for different crystal thickness,while those of Li atoms are invisible.The image contrast variation for Nb and O atoms with the crystal thickness is consistent with the prediction given by the theory of pseudo-weak-phase object approximation.Besides,the image simulation shows that even when the image defocus is close to the Scherzer focus,the image processing via deconvolution is beneficial to improve the image quality and is necessary to reveal the O atoms individually.