Direct precipitation of spinel type oxide ZnGa2O4 from aqueous solutions at low temperature below 90°C

Ultrafine ZnGa2O4 spinel particles ranging from 4 to 11 nm of crystallite size were directly precipitated. by dropping a mixed solution of zinc sulfate and gallium sulfate into aqueous NH3 at a temperature of 25 to 90 degreesC with stirring. They were also precipitated by aging the mixed solution in the presence of either urea or hexamethylenetetramine at 90 degreesC. The crystallite size of the precipitates decreased with increasing concentration of the metal ions in the solution and with decreasing temperature of the solution, which is explained by the formation of a large number of nuclei. (C) 2001 Elsevier Science Ltd. All rights reserved.