Obtenção de luminóforos RGB pelo processo de pirólise de aerossol

• Main Author: Freiria, Gabriela Simões
• Publication Date: 2017
• Format: Master thesis
• Language: por
• Source: Repositório do Centro Universitário Braz Cubas
• Download full: https://repositorio.cruzeirodosul.edu.br/handle/123456789/451
• topic: Pirólise de aerossol; Niobato de lantânio; Európio; Disprósio; Luminóforo; Luminescência; Diodo emissores de luz; CNPQ::CIENCIAS EXATAS E DA TERRA

In this work, materials based on LaNbO4 containing Eu3+, Dy3+ ions were synthesized by the Spray Pyrolysis process with the purpose of obtain RGB luminophores. Among different ways for the preparation of luminophores materials, one of the most promissing is the Spray Pyrolysis process due to its advantages as speed and purity of final product. Samples containing only the Eu3+ ion (used here as the structural probe) were synthesized using the temperatures of 900, 700 or 500 °C in the decomposition / heat treatment zone. The results indicated that the sample treated at 900°C had a crystalline structure and a quantum yield higher than the other samples treated at lower temperatures. Therefore, the other samples containing only Dy3+ or Dy3+ and Eu3+ were synthesized using a temperature of 900°C. The variation of the concentration of the Dy3+ ion in the samples provided the change of the chromaticity coordinates from the blue region to the white region of the diagram, when excited at 254 nm, and the sample containing 5.0 mol% presented to chromaticity coordinates at the center of the Diagram, related to white color (x = 0.33 and y = 0.33). Scanning electron micrographs showed spherical particles with rough surfaces and diameters ranging from 20 nm to 1.5 μm. For the samples containing the Dy3+ and Eu3+ ions, it was possible to observe changes in the emission and excitation spectra as a function of the ion concentration. However, the experimental lifetime of the Eu3+ ion was higher than that of the Dy3+ ion, regardless of excitation concentration or wavelength. Therefore, the structural/morphological properties were evaluated together with the luminescent ones in order to develop new luminophores for possible applications in light emitting diodes.