Cadmium oxide octahedrons and nanowires on the micro-octahedrons: A simple solvothermal synthesis

Cadmium oxide (CdO) micro-octahedrons and nanowires were synthesized by a simple solvothermal process using ethanol as a solvent. The amount of NaOH and the synthesis temperature were the key parameters to control the phase and morphology of the as-synthesized products. The phase purity of the samples was determined through X-ray diffraction (XRD). Lower concentration of NaOH and higher-synthesis temperature favored the formation of CdO micro/nanostructures. Morphologies of the products were identified through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). At higher temperature and low NaOH concentrations, nanowires were protruded from the octahedron facets. HRTEM images and SAED patterns reveal the single-crystalline nature of the octahedrons and polycrystalline nature of the nanowires. Cd(OH)₂ samples, obtained at low synthesis temperature, were annealed at different temperatures to test the feasibility of the products to transform to CdO. Positron annihilation measurements were carried out to study the defects of the nano/microstructures. Electrical resistivity measurement showed semiconducting behavior of CdO samples.