PREPARATION AND PROPERTIES OF UNIFORM COATED INORGANIC COLLOIDAL PARTICLES .9. TITANIA ON COPPER-COMPOUNDS

Solutions of copper(II) nitrate containing urea aged at moderate temperatures can yield either uniform spherical amorphous particles of Cu2(OH)2CO3 or crystalline platelets of Cu2(OH)3NO3. The latter solids precipitate when the solutions are extensively purged with argon during the reaction. Calcination of both kinds of powders at 700-degrees-C yielded CuO, yet the particle shapes were retained while their surfaces roughened. The spherical particles of Cu(II) basic carbonate were coated with amorphous titania by hydrolysis of Ti(IV) butoxide. The thickness of the shell could be varied by altering the experimental conditions. On heating the powders of coated particles, the cores converted to CuO and the coated layers to a mixture of anatase and rutile.