Abstract: Molybdic acid aggregates were prepared by the reaction of ammonium molybdate with HNO3 and HCl in a coexisting HAc or cetyl-trimethyl ammonium bromide (CTAB) solution, respectively. The results indicate that the size and morphology of as-prepared molybdic acid aggregates and annealed products-α-MoO₃ powder were affected by the concentration of ammonium molybdate, HAc and CTAB. The molybdic acid aggregates with diameter of 1--2μm and length of several decades-micron can be obtained by the reaction of higher-concentration ammonium molybdate with HNO₃ in a coexisting HAc or CTAB solution, repectively. After the as-prepared molybdic acid aggregates are annealed at 500--600℃ for 3h, the nanometer-scaled lamellate and sub-micrometer MoO₃ powder are prepared. In addition, irregular molybdic acid aggregates rods are achieved by the reaction of lower-concentration ammonium molybdate with HCl in a coexisting CTAB solution.

Key words: molybdic acid, aggregates, MoO₃, HAc, cetyl-trimethyl ammonium bromide