Luminescent silicate nanostructures via non conventional synthesis routes

Abstract

Silicates comprise a class of interesting and attractive materials, due to their broad structural variety, high chemical stability and water resistance, transparency to visible light, ease of preparation and low cost. Among the various applications, we highlight their use as hosts for luminescent materials and long-lasting phosphorescence materials. However, the conventional synthetic routes generally involve heating at high temperatures for long periods of time, resulting in materials with irregularly shaped, large particles and agglomerates. Recently, we have described a new low temperature synthetic route por the preparation of CdSiO3 and SrSiO4 nanostructures. These are, respectively, a host for long lasting phosphors and a host for luminescent materials. The conventional synthetic routes involve heating at 1050C for 3 h and 1100C for 6 h, respectively. In our research, we have obtained these materials after heating at 580C/1h and 600C/3h, respectively. (Santana, Soares, Almeida e Vichi, J. Braz. Chem. Soc., in press)The objective of this proposal is to obtain M2SiO4 (M = Sr, Zn) and CdSiO3 doped with rare earth ions using alternative, low-temperature routes. The resulting materials will be characterized by x-ray diffractommetry (XRD), scanning and transmission electron microscopy (SEM/TEM), focused ion beam microscopy (FIBM), surface area analysis (BET method), vibrational spectroscopy (IR and Raman), solid-state nuclear magnetic resonance (NMR) and visible/UV absorption/emission spectroscopy.The development of environmentally friendly synthetic routes has become of major importance in recent years, with respect to two points: contamination and energy efficiency. With respect to environmental contamination, the establishment of lower limits for emissions and contaminants has spurred the need for the development of synthetic routes which are more environmentally friendly.As for energy economy, the development of lower energy routes is a part of a general effort of mankind to reduce energy consumption, increasing energy efficiency, leading to a reduced use of fossil fuels. In this respect, two approaches are suggested in this proposal: the use of lower temperature for shorter periods and the development of materials which are capable of absorbing solar energy, which is later irradiated for long periods of time. (AU)