Synthesis of TiO2 nanoparticles out of fluoride solutions

In the paper, synthesis process of the TiO2 particles was discussed, from the fluoride solution, through TiO2·nH2O gel thermal precipitation and decomposition, and its impact on the further sintering of the obtained powders. It was demonstrated that the main phase of the obtained titania was anatase. Morphology of the obtained TiO2 can be controlled through variations of the precipitation temperature and the emulsifier concentration. It was found that the addition of the chloride ions during gel formation caused crystallization of the (NH4)2TiOF4 phase. When it underwent decomposition under heating, agglomerated particles in form of rods several micrometers long were synthesized. Obtained powders were sintered, and both the sintering process and the final bulk structures were examined. The results indicated the lowest microhardness of 540 kg/mm2 in the specimens prepared out of the powders synthesized without emulsifier, while the highest hardness of 1450 kg/mm2 was reached when the TiO2 particles had been precipitated at room temperature with emulsifier proportion С(Ti):C(OР9) = 1:0.5. However, further increase of the emulsifier concentration led to the decrease of hardness.