Size and Morphology Control of Ultrafine Refractory Complex Oxide Crystals

High-temperature complex oxides are of considerable interest as their applications cover a broad spectrum from catalytic to optical technology. Indeed, new exciting opportunities might emerge if these high-temperature complex oxides, in which structure crystallization is achieved at temperatures T > 1000 degrees C, could be synthesized as nonaggregated, ultrafine building blocks. In general, such refractory complex oxide particles are difficult to synthesize as ultrafine crystals because of the strong driving force available for sintering and coarsening in this high-temperature range. This paper reports a new synthetic process for the preparation of nonaggregated, ultrafine barium hexa-aluminate, BaO, 6Al(2)O(3), (BHA), and Ba0.9Eu0.1MgAl10O17, (BAM) crystals in which structure crystallization occurs around 1300 degrees C. Our process is based on the Ba2+ and Al3+ ions high-temperature controlled diffusion from carbon-inorganic hybrid compounds prepared from soft chemistry routes. Control of morphology of these refractory complex aluminates displaying nanoplatelets morphology was achieved via the tailoring of high-temperature diffusion lengths of the various cations involved in the formation of these ultrafine refractory crystals.