Particle production and anatase formation in amorphous particles at in-droplet hydrolysis of titanium alkoxide

Anatase crystallization in amorphous particles was investigated during drop let-to-particle synthesis of titania. Ethanolic solution of carboxylic acid -modified titanium tetrabutoxide precursor, including water, was dispersed and conveyed to a tube flow reactor at 350-600 degreesC. The formed submicr on-sized particles were characterized by aerosol measurements, X-ray diffra ction, and electron microscopy. An aerosol number mode was observed at part icle diameter of 250 nm representing the particles formed of droplet drying . Additional ultrafine particles were formed in air atmosphere at 450 degre esC and in nitrogen at 600 degreesC from decomposition and outgassing of pr ecursor species and a subsequent particle formation. An anatase crystalline phase was observed in the particles produced at 500 degreesC in nitrogen. The location of anatase formation was investigated by TEM from thinned sect ions of the particles. The crystals were observed near the surfaces and ind icating columnar growth. (C) 2001 Elsevier Science Ltd. All rights reserved .