Banca de DEFESA: PATRICIA NEVES DE MEDEIROS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : PATRICIA NEVES DE MEDEIROS
DATA : 22/06/2017
HORA: 09:00
LOCAL: Sala de reuniões do DEMat
TÍTULO:

Synthesis of strontium-calcium indate (Sr_0,9Ca_0,1In₂O₄) codoped with rare earth ions for application in photoluminescence

PALAVRAS-CHAVES:

Strontium indate, ultrasonic spray pyrolysis, rare earths, photoluminescence.

PÁGINAS: 90
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Nanostructured ceramic materials have been extensively studied in recent years due to their great potential in areas such as photoluminescence, photocatalysis, electrochemistry. These materials allow the improvement of various properties due to their nanometric dimensions. The strontium indate (SrIn₂O₄) and the calcium indate (CaIn₂O₄) are oxides with structure of spinel type and orthorhombic crystalline system, being reported in the literature as host lattice for luminescent materials. The ultrasonic spray pyrolysis method allows continuous one-step production of particles with high purity. In this context, the synthesis of Sr_(1-x)Ca_xIn₂O₄ was performed using the spray pyrolysis method, investigating the influence of the Ca²⁺ ion content on the photoluminescent properties of the solid solution. After analysis of the results it was verified that the composition Sr_0,9Ca_0,1In₂O₄ emitted higher intensity photoluminescent and was selected as host lattice for Rare Earth activator ions (RE³⁺). The indate Sr_0.9Ca_0.1In₂O₄: Eu³⁺, Tb³⁺, Tm³⁺, co-doped at different concentrations (%mol) were synthesized by spray pyrolysis. The obtained samples were characterized by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (MEV-FEG), photoluminescence measurements (PL), UV-visible spectroscopy (UV-VIS) and photocatalytic activity by degradation of the methylene blue dye. The results of X-ray diffraction confirmed the formation of the strontium indate phase with orthorhombic structure. From the micrographs it can be observed the formation of microspheres composed of nanoparticles. The photoluminescence spectra of the Sr_(1-x)Ca_xIn₂O₄ samples showed broadband emission and the Sr_0,9Ca_0,1In₂O₄ RE³⁺ (Eu³⁺, Tb³⁺, Tm³⁺) showed narrow and intense bands, characteristic emissions of RE³⁺ ions. The Sr_(1-x)Ca_xIn₂O₄ samples showed low photocatalytic activity, with a maximum degradation of 45% of the dye. According to the results obtained, the strontium and calcium indate co-doped with RE³⁺ ions presents potential application in the area of photoluminescence.

MEMBROS DA BANCA:
Presidente - 1802888 - FABIANA VILLELA DA MOTTA
Interno - 1883170 - MAURICIO ROBERTO BOMIO DELMONTE
Externo ao Programa - 4213130 - MICHELINE DAMIÃO DIAS MOREIRA
Externo à Instituição - MAXYMME MENDES DE MELO - IFRN
Externo à Instituição - VINÍCIUS DANTAS DE ARAÚJO - UFRPE