Synthesis of nano-sized powders of transparent conductive aluminum-doped zinc oxide by electrolysis-modified co-precipitation method

Nano-sized powders of transparent conductive aluminum-doped zinc oxide (AZO) have been successfully prepared by electrolysis-modified co-precipitation method. By adding ammonium hydroxide into the precursor solution prepared by electrolytic dissolution of zinc metal in a buffered electrolyte solution of nitric acid and ammonium nitrate with adequate addition of aluminum nitrate, co-precipitate precursors of AZO with particle size between 30 to 60 nm were produced. After washing, filtering, and drying of the co-precipitates, nano-powders of AZO with wurtzite structure were produced when the dried co-precipitate precursors were calcined at temperature above 800degC. By aging at pH = 5 and co-precipitating at pH = 8.0, the atomic ratio of Al/Zn of the nano-powders could be maintained throughout the synthesis. After calcining at 1000degC in air for 2 hours, nano-sized powders of AZO with ZnO wurtzite structure and particle size between 200 to 500 nm were synthesized. Finally, it was found that both the particle sizes of co-precipitate precursors and calcined nano-powders of AZO could be decreased by increasing the pH of the electrolyte solution for electrolytic dissolution.