Microstructural study of different LDH morphologies obtained via different synthesis routes

In order to better understand the relationship between LDH synthesis parameters and their particle sizes, diverse carbonate intercalated NiAl-LDH phases were prepared using different coprecipitation conditions and their structure, microstructure and morphology were characterized. The samples were synthesized by coprecipitation either at constant pH, in strong alkaline medium or using urea decomposition. The influence of a post-synthesis hydrothermal treatment was also investigated. A well crystalline NiAl-CO₃ phase but containing a high stacking fault density was obtained by combining a strong basic medium and hydrothermal treatment at 120 °C for 24 h. Interestingly, the hydrothermal treatment increases the crystallinity of the samples but does not eliminate stacking faults. The crystallite sizes determined by modeling X-ray diffraction peak broadening with linear combinations of spherical harmonics are fully consistent with TEM observations confirming the validity of the approach used and indicating that the particles are probably small single crystals.