Efeito da razão ácido cítrico/cátions metálicos na fotoluminescência do TiO2 sintetizado pelo método Pechini.

Abstract

Nanotechnology has been introduced in applications in the most diverse technological areas, with the intention to develop new materials or even improve existing materials. In this context, a material that stands out for use in various applications is titanium dioxide (TiO2), mainly due to its thermal and chemical stability properties and optical properties. However, these properties are dependent on the type and amount of phase and of the morphology, which is directly dependent to the processing method. Thus, this work proposes to synthesize TiO2 nanoparticles by Pechini method in the molar proportions of citric acid/metal cations of 1:1, 2:1, 3:1, 4:1 and 5:1 in order to evaluate the influence of the anatase and rutile phases in the structure, morphology and photoluminescent properties of TiO2. The nanoparticles were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), textural analysis, density, scanning electron microscopy (SEM), emission spectroscopy and excitation and gap band by diffuse reflectance spectroscopy. The results show the formation of the anatase and rutile phases in all proportions of citric acid/metal cations evaluated. Morphologically the samples had agglomerate size between 15.89 and 19.34 μm with density around 3.7 g/cm3. The respect to the photoluminescent properties, it was observed that the increase of the ratio of the rutile phase to the anatase phase did not significantly alter its gap band, obtaining values between 2.97 and 3.00 eV. The maximum emission intensity occurred at the wavelength of 533 nm for the 3:1 sample and the maximum excitation intensity produced by the photon absorption occurred in the 2:1 sample at wavelength of 451 nm.