Synthesis of ferroelectric Bi4Ti3O12 by alternative routes:: Wet no-coprecipitation chemistry and mechanochemical activation

Novel synthesis methods have been investigated for the preparation of Bi4Ti3O12 ferroelectric Aurivillius-type powders, namely, the wet no-coprecipitated chemistry using a 12-butylamine aqueous solution and two mechanochemical activation techniques (vibrating and planetarium mills). For the sake of comparison, Bi4Ti3O12 powders were also produced by the traditional ceramic route. The syntheses of the crystalline phases were obtained by annealing of the precursors at different temperatures and times. Both the precursors and the thermally treated products were characterized by means of X-ray powder diffraction, thermal analysis, and scanning electron microscopy. The Aurivillius phase was found to appear at 600 degreesC for vibrating and 500 degreesC for planetarium-milled precursors. These temperatures are 250-350 degreesC lower than those reported for the traditional ceramic route (850 degreesC). Moreover, the stabilization at room temperature of a new fluorite Bi-Ti-O structure was obtained by use of the planetarium milling precursor. The microstructure of the powder investigated by SEM was correlated with the XRD results. In particular, monolithic Bi-4-Ti3O12 grains of a few microns in size were achieved by means of the wet chemistry method.