Tracking in Detail the Synthesis of Cadmium Oxide from a Hydroxyl Gel Using Combinations of in Situ X-ray Absorption Fine Structure Spectroscopy, X-ray Diffraction, and Small-Angle X-ray Scattering

The synthesis of cadmium oxide from a gel of cadmium hydroxide has been followed in situ using unique combinations of X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) spectroscopy, and small-angle X-ray scattering (SAXS). XRD and XAFS enable the crystallography, particle size, and local structure to be quantified as the hydroxyl gel converts into cadmium oxide around 182 °C. SAXS measures the evolving microstructure, with cadmium oxide growing dendritically in a fractal geometry, initially from rough nanoparticles. Major growth and densification takes place between 325 and 550 °C. The implications for characterizing the precipitation of cadmium oxide nanoparticles in zeolitic hosts are considered.