Microstructure Related Conductivity in La₂Mo₂O₉ Ceramics

International audienceLa2Mo2O9 oxides were synthesized for the first time by ultrasonic assisted spray-pyrolysis process (SP) and conventional solid-state reaction (SSR). A comparative investigation of the morphology, microstructure, and structure was undertaken on the powders and the ceramics. Poorly crystalline powders containing organic residues were obtained by SP at 400 °C. On the contrary, high purity polycrystalline spherical particles ranging from 50 nm to 3 μm and homogeneous in composition were obtained at 600 °C and consisted of crystallites of 30 nm. The ceramics prepared from these powders obtained by spray pyrolysis at 600 °C present small particle size (2−3 μm). The sintering temperature was significantly reduced by 300 °C with comparison to the one obtained for pellets starting from SSR powders. A careful line broadening analysis of the X-ray diffraction patterns demonstrated a crystalline growth from 30 nm to only 150 nm after sintering process. Electrical properties of fine ceramics starting from SP powders were found fairly similar to conventional LAMOX micronic ceramics from room temperature to 850 °C