Role of the oxidizing agent to complete the synthesis of strontium aluminate based phosphors by the combustion method. Issue 4 (10th December 2014) - Rojas-Hernandez, R. E.
Abstract : Well-controlled fuel/oxidizing agent ratio allows to synthesize nanostructured strontium aluminates lamellar particles with high luminescence properties. Abstract : The influence of processing parameters on the phase formation of strontium aluminates doped with Eu 2+ and Dy 3+ by the combustion method has been evaluated. The addition of a slight excess of urea as a fuel has an important effect on the phase formation, but a larger amount of urea inhibited the strontium incorporation into the stuffed tridymite-like structure. The experimental results show that it is possible to incorporate a larger amount of urea than the theoretical one by adding nitric acid as an oxidizing agent. The presence of an oxidizing agent promotes both effective chelation of the cations and a higher crystalline order on strontium aluminate. Nanostructured lamellar particles have been obtained in a single step and the particles are well crystallized. The combustion method avoids the standard requirements of post-thermal treatments in a reducing atmosphere to promote the appearance of Eu 2+ cations. A higher amount of urea in the presence of the oxidizing agent produces strontium aluminate particles with higher phosphorescence brightness, owing to the increase of the reduction process Eu 3+ to Eu 2+ . The luminescence properties correlate with the crystallite size of the strontium aluminate. The results demonstrate a pathway to obtain phosphorescent pigments with sizes down to 10 μm.