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

Author(s)

Alessandro Bruno Silva Garcia

• Document type: Master's Dissertation
• Press: São José do Rio Preto. 2019-03-26.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências Letras e Ciências Exatas. São José do Rio Preto
• Defense date: 2019-03-01
• Advisor: Ana Maria Pires

Abstract

In this work, new multi shell type inorganic-organic hybrids with potential application in light converters were developed. As an inorganic component, a core@shell system composed of LaAlO3 doped with Tb3+ as core, a first layer of lanthanum oxide doped with Eu3+ and a second layer of aminofunctionalized SiO2 was used. The lanthanum aluminate matrix was prepared from the modified Pechini methodology, and a systematic study of the percentage of dopant was performed for both Tb3+ and Eu3 + doping, and the optimum concentration was determined to be 9% and 11%, respectively. The amino functionalized SiO2 coating, in turn, was performed by the modified Stöber method. From the reaction of the amino groups on the surface of the silica there was the anchoring of Schiff bases which were coordinated to the rare earth ion (Eu3+); water molecules coordinated to the metal ion were then replaced by β-diketone type ligand. All steps involved in the preparation of the hybrid systems were monitored by suitable characterization techniques appropriated to each system, such as thermal analysis, X-ray diffraction, scanning and transmission electron microscopy, vibration absorption spectroscopy in the IR region and photoluminescence. The Pechini methodology successfully produced the planned multishell systems, the final hybrid consisting of a lanthanum aluminate 5% doped with terbium(III) as core with an average diameter between 20 and 60 nm, covered with two non-crystalline layers doped with 5% of europium(III), and finally a 5% aminofunctionalized silica layer with a total thickness of almost 2 nm. The presence of Eu3+ in the shell and Tb3+ in the core facilitated the modulation of color according to the excitation. The functionalization and anchoring of complexes with Eu3+ was also successful, being possible to detect emissions of the core@shell system and also of the anchored complex. In this way, the materials produced are promising for application in light emitting devices. (AU)

• FAPESP's process: 17/13688-1 - Lanthanum aluminate in the planning of functionalized luminescent core@shell systems containing the Eu3+ and Tb3+ ions for application in light converting devices
• Grantee: Alessandro Bruno Silva Garcia
• Support Opportunities: Scholarships in Brazil - Master