Papers by Keyword: Anatase Titanium Dioxide

Abstract: The nanosized TiO₂ is prepared by micro-emulsion process in the system of cyclohexane / [Span80 combined with OP-10] / water with TiCl₄ as raw material. The selection method of the surface-active agents was investigated and the influence of amount of surfactant, water / oil ratio and concentration of reactants on the particle size were discussed in this work. The temperature schedule, crystal structure, particle size distribution and appearance of the nanocrystalline TiO₂ were analyzed by differential thermal analysis (DTA) combined with X-ray diffraction (XRD), laser particle size analysis (LPSA) and scanning electron microscope (SEM). The results showed that: under these conditions of mixture of 8g Span80 and 2g OP-10 as the emulsifier, water / oil mass ratio of 1/4, TiCl₄ concentration of 0.6mol / L and calcinations temperature of 510°C, nanoTiO₂ powder with smaller particle size and better dispersion was prepared . And the average size of the product was 27.3nm.

Abstract: Titanium dioxide (TiO2) nanopowders were prepared by laser-induced pyrolysis. Raman scattering showed that prepared TiO2 nanocrystals have anatase TiO2 structure. Specific surface area of the powders varies from 84 to 110 m2/g, while the grain size of nanoparticles is between 30 and 70 nm, depending on preparation conditions. We measured photoluminescence (PL) spectra of TiO2 nanocrystals. Under laser irradiation with photon energy between 2.41 and 2.71 eV the TiO2 nanocrystals displayed strong visible light emission, even at excitation power as low as 0.05 W/cm2. The line shape and position of this broad luminescence band vary with excitation energy. As PL spectra of anatase TiO2 can be attributed to three kinds of physical origins (self-trapped excitons, surface states and oxygen vacancies) in this paper we try to resolve which of them are dominant for different TiO2 nanopowders of different grain size.