Lanthanum aluminate in the planning of functionalized luminescent core@shell systems containing the Eu3+ and Tb3+ ions for application in light converting devices

Abstract

The central strategy of the present project is the development of novel inorganic-organic hybrid materials for application in light-converting devices. In the planning of such hybrids an inorganic component was selected as being a core/shell type system composed by LaAlO3 doped with the Eu3+ or Tb3+ as the core, a first shell of lanthanum oxide doped with Tb3+ or Eu3+ (if the core has Eu3+ the shell will be doped with Tb3+ and vice versa) and a second shell of aminofunctionalized SiO2. For the preparation of the lanthanum aluminate matrix the modified Pechini and sol-gel methods will be adapted and tested and the aminofunctionalized SiO2 coating will be carried out using the modified Stöber method. The purpose of the use of silica is to protect the particles surface and at the same time to act as the coupling agent of the organic part. Thus, from the reaction of the amino groups on the surface of the silica the anchoring of Schiff bases will be performed and then the rare earth ions (Eu3+, Tb3 or La3+) will be coordinated to them; water molecules that could be also coordinated to the metal ion and act as luminescent quenchers will be replaced by ²-diketone type ligands. All the steps involved in the preparation of the hybrid systems will be monitored by suitable and appropriate techniques of characterization to each system, such as X-ray diffraction, scanning and transmission electron microscopy, vibration absorption spectroscopy in the IR region and Raman, spectroscopy in the UV-Vis, diffuse reflectance and luminescence spectroscopies, thermal and elemental analyzes, among others. Specifically, from the photoluminescence data, the color coordinates of the produced compounds and the intensity and quantum efficiency parameters will be estimated, in order to correlate with the results of the other techniques for a comparative analysis of the performance of the systems produced as light converters. (AU)