resumo
Titanium dioxide exists in a large number of polymorphs, the most common ones being, in order of abundance, rutile, anatase and brookite. Recently, there has been an increasing degree of attention on TiO2, due to its photocatalytic and antibacterial properties. In this work, titania nanopowders synthesized via an aqueous sol gel method were modified with silver and/or tungsten, with potential application as photocatalysts and antibacterial agents. The dried gels were thermally treated at two temperatures, and the occurrence of amorphous phase-in both dried and calcined gels-was obtained using the Rietveld method. In powders calcined at 600 degrees C, the crystal structure of rutile was determined with the Rietveld method on the full profile fitting of the X-ray powder diffraction patterns, while microstructural information was achieved by means of Williamson-Hall plots and line broadening analysis methods. The photochromic property of the Ag and W/Ag modified samples-when subjected to both UV- and visible-light irradiation and for different time exposures-was also investigated via UV-Vis spectroscopy. Powders were shown to possess a tuneable photochromism due to the surface plasmon resonance of the added silver, depending on the firing temperature, light (and time) exposure, and on whether or not tungsten was present in the nanopowders. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
palavras-chave
X-RAY-DIFFRACTION; VISIBLE-LIGHT PHOTOCATALYSIS; SURFACE-PLASMON RESONANCE; OPTICAL-PROPERTIES; TITANIUM-DIOXIDE; METAL NANOPARTICLES; MULTICOLOR PHOTOCHROMISM; RUTILE TRANSFORMATION; HYDROGEN-PRODUCTION; THIN-FILMS
categoria
Materials Science; Metallurgy & Metallurgical Engineering
autores
Tobaldi, DM; Pullar, RC; Gualtieri, AF; Seabra, MP; Labrincha, JA
nossos autores
David Maria Tobaldi
Investigador
João António Labrincha Baptista
Professor Catedrático
Maria Paula Seabra
Professor Auxiliar
Rob Pullar
Colaboradoragradecimentos
The authors are obliged to Prof. L.D. Carlos and Prof. T. Trindade (CICECO/University of Aveiro, Portugal) and M. Lassinantti Gualtieri (University of Modena and Reggio Emilia, Italy) for their helpful and constructive discussions. The authors also acknowledge PEst-C/CTM/LA0011/2011 programme. M.P. Seabra and R.C. Pullar wish to thank the FCT Ciencia2008 programme for supporting this work.