Correlation among Structure, Microstructure, and Electrochemical Properties of NiAl–CO3Layered Double Hydroxide Thin Films

Abstract

We studied a series of NiAl–CO3 layered double hydroxides (LDHs) of various degrees of crystallinity prepared by a glycine-assisted hydrothermal method. The structures and the microstructures were determined by Rietveld refinement with a spherical harmonic-implemented algorithm using high-resolution synchrotron powder X-ray diffraction (XRD) data. These XRD results combined with transmission electron microscopy (TEM) observations indicate that the broadening of 00l diffraction lines is mainly due to size effects, while both size and strain effects contribute to the anisotropic broadening of the other hkl reflections. The in-plane TEM dimensions of LDH platelets are found larger than the coherent lengths in the 110 direction, indicating a noncoherent coalescence of domains during crystal growth. The DIFFaX program was also used to model structural defects, i.e., CO32–/SO42– interstratification and intergrowth between rhombohedral 3R1 and hexagonal 2H1 polytypes. Furthermore, the distribution of the cations...