Banca de QUALIFICAÇÃO: ANDERSON DE AZEVEDO GOMES SANTIAGO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDERSON DE AZEVEDO GOMES SANTIAGO
DATE: 04/11/2020
TIME: 14:00
LOCAL: Sala virtual (videoconferência)
TITLE:

Study of the photoluminescent properties of Mg1-xSrxMoO4 and Zn1-yCayWO4 heterostructures obtained by the ultrasonic spray pyrolysis method

KEY WORDS:

molybdate; tungstate, heterostructure; ultrasonic spray pyrolysis; and photoluminescence.

PAGES: 88
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

Molybdates and tungstates are inorganic materials with great application potential as white light-emitting diodes (LEDs), being an alternative to traditional lighting sources. In this study, the synthesis and characterization of Mg1-xSrxMoO4 (x = 0; 0.25; 0.50; 0.75 and 1) and Zn1-yCayWO4 (y = 0; 0.2; 0.4; 0.6, 0.8 and 1), prepared by the ultrasonic pyrolysis spray method and their photoluminescent properties were investigated. Using X-ray diffraction, the monoclinic phase of β-MgMoO4 was observed for x = 0 and the tetragonal scheelite phase of SrMoO4 was observed for x = 1, while the monoclinic phase of ZnWO4 was observed for y = 0 and the tetragonal scheelite phase of CaWO4 was observed for y = 1. The formation of a heterostructure composed of both phases was observed for compositions for the intermediate x and y values. Scanning electron microscopy images showed that the Mg1-xSrxMoO4 and Zn1-yCayWO4 particles exhibit a spherical morphology formed by several primary nanoparticles. Raman scattering spectroscopy allowed the precise identification of Raman modes for different compositions and their assignment to SrMoO4 or β-MgMoO4 modes. The energies of the bandgap were determined to fluctuate between 4.25 eV and 4.44 eV for Mg1-xSrxMoO4 and between 3.79 eV and 3.99 eV for Zn1-yCayWO4, being influenced by structural disorder degree of materials. The photoluminescence emission spectra of the particles showed neutral and cool white emission with high quality white light (CRI> 80%). Mg1-xSrxMoO4 samples synthesized with x ≤ 0.50 are potential materials for application in LED lamps (6500 K) and pure white light sources (5500 K) whereas Zn1-yCayWO4 samples can be considered as white light sources promising, mainly for the sample synthesized with y = 0.8 for application in LED lamps (6500 K).

BANKING MEMBERS:
Externo à Instituição - LUÍS PRESLEY SEREJO DOS SANTOS
Interna - 1802888 - FABIANA VILLELA DA MOTTA
Externo ao Programa - 2941160 - JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
Externo à Instituição - MARIO GODINHO JUNIOR - UFG
Presidente - 1883170 - MAURICIO ROBERTO BOMIO DELMONTE