Caracterização das propriedades estruturais de molibdatos e óxidos nanoestruturados através de espectroscopia Raman

Abstract

In this work we have been investigated the vibrational properties of nanostructured oxides (monoxides) and modified molybdates with yttrium and indium by means of Raman spectroscopy. In the monoxides nanostructured Al2O3, CeO2, ZrO2, TiO2, MnO2 and SnO2, were focused the pressure and temperature effects over the referred molybdates stability. While for the yttrium and indium molybdates, besides temperature effects also has been studied the pressure effects on them. The change of yttrium concentration in the molybdate allows in some cases remark the Negative Thermal Expansion (NTE). For the nanostructured oxides, the nanoparticles of ZrO2 and TiO2 exhibit different phase transitions at high temperatures due each compound apart. When compared with traditional oxides, the mentioned nanostructured oxides exhibit an excelent catalitic performance in the dehidratation of the glicerol, due synergic effects arising from access to active sites caused by defects in its structure. Due the electronic effect of the CeO2 and its stability at high temperatures, this material is a promising option for catalytic applications.