Structural Arrangement in Close-Packed Cobalt Polytypes

In this paper, we present a comprehensive study on how stacking faults, crystallite size, crystallite size distribution as well as shape and strain dictate the nature of the X-ray powder diffraction patterns of small ( 20 nm) cobalt (Co) nanoparticles. We provide a unique library of simulated diffractograms which can be used for fingerprint analysis. Likewise, the simulated data are used as a basis for structural refinements of experimentally obtained X-ray powder diffractograms. We provide examples of using the library for fingerprint analysis and for full structural analysis of synthesized Co nanoparticles. Structural refinements presented in this study allow to reveal fine structural details that directly correlate to different behavior upon heating in a CO atmosphere relative to a H2 or He atmosphere. All calculations were performed using the Discus package and the Debye scattering equation.