KINETIC INVESTIGATION OF SOLID-STATE SYNT HESIS OF BARIUM-TITANATE USING BARIUM NITRATE AND TITANATE DIOXIDE

The aim of this work is to study the solid state synthesis of barium t itanate, from barium nitrate and titanium dioxide. The reaction path w as initially identified, i.e. the intermediate phases that appear duri ng the reaction, from a thermodynamical and experimental point of view . Experimental conditions of temperature and partial pressures of nitr ogen monoxide and oxygen (which are the main gases released during the reaction) have been found, such as BaTiO3 is the stable phase. The ex perimental kinetic curves have been obtained using thermogravimetry, u nder isothermal conditions (500 degrees C), under controlled partial p ressures of nitrogen monoxide and oxygen. These two gases have an inhi biting effect on the reaction. A qualitative interpretation for the tr ansformation is proposed, as well as a geometrical modeling which lead s to the variation of the fractional conversion with time. We have als o tried to account for the influence of the gaseous atmosphere on the reaction rate via a physico-chemical modeling.