Supercritical fluid technology : a reliable process for high quality BaTiO3 based nanomaterials
Résumé
Ferroelectrics materials have been tremendously attractive since the 40 s with the discovery of ferroelectricity in metal oxide perovskite materials and more precisely in barium titanate. Due to their high potential for industrial applications, intensive research has been carried out to better understand their behavior and develop processes to produce them. Trying to face the down scaling demand of high quality particles towards the nanometer range, some conventional methods such as the solid state one reach their limits. The development of other processes are thus required and the synthesis in supercritical fluids can be considered as a promising alternative. This technology exhibits very interesting characteristics such as fast continuous synthesis (few seconds) of high quality nanoparticles (well crystallized nanoparticles with narrow size distribution) with controlled composition (Ba1−xSrxTiO3 with 0 ⩽ x ⩽ 1) at intermediate synthesis temperatures (<400 °C) with the use of non-toxic solvents (water, ethanol). Reaching the nanometer size range, the intrinsic properties of ferroelectric materials change compared to the bulk. Consequently a deep study concerning the crystalline structure, the presence of defects and the surface chemistry of those nanoparticles has to be achieved to control their properties for further use in functional devices.
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