Internally Composite Uniform Colloidal Cadmium Sulfide Spheres

Monodispersed spherical polycrystalline cadmium sulfide particles were synthesized by precipitation in acidic aqueous solutions during the thermally controlled reaction between cadmium nitrate and thioacetamide. The effects of the concentration of the components and of the nitric acid on the colloidal growth dynamics and the properties of the final products were investigated. The higher content of nitric acid in reacting solutions and the higher molar ratio [Cd²⁺]/[S^2-] resulted in larger subunit crystallites and bigger final particle sizes. Furthermore, solids precipitated at higher molar ratios were of better crytallinity and indicated partial cubic crystal lattice of the subunits, while those produced at lower [Cd²⁺]/[S^2-] ratios displayed the X-ray pattern, characteristic of hexagonal crystal lattice. The size of the crystallite, the type of their lattice, and the size of the final particles affected their reactivity at high temperatures.