Effect of temperature during the spray pyrolysis synthesis of silver nanopowder

We report the results of the synthesis and characterization of Ag, AgO, AgNO3 nanopowders or mixtures of them, obtained by spray pyrolysis technique. An aqueous solution of AgNO3 with a concentration of 0.2 mol/L was sprayed through a horizontal tubular furnace where the solvent was evaporated and pyrolytic reaction occurs producing AgNO3, AgO and Ag particles. The synthesis was made at 500, 600 and 700 oC. The obtained material was analyzed by Transmission Electron Microscopy, and the optimal temperature to obtain particles of around 10 nm was 600 oC. The X-rays and Electron Diffraction analysis determined the coexistence of the phases of Ag, AgO and AgNO3, whereas the measurement of x-rays fluorescence the presence of Ag was detected. The solution concentration and the carrier flow, the temperature and the temperature gradient in the furnace influence in the phase and size of the particle.. (author)