Banca de QUALIFICAÇÃO: FERNANDA KARINE FONSECA DE OLIVEIRA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : FERNANDA KARINE FONSECA DE OLIVEIRA
DATE: 24/02/2021
TIME: 09:00
LOCAL: https://meet.google.com/uib-ygyj-mwy
TITLE:

Synthesis and characterization of cerium molybdate by the microwave-assisted hydrothermal method: application as ozone gas sensor

KEY WORDS:

Molibdato de cério. Método hidrotérmico assistido por micro-ondas. Propriedades microestruturais. Ozônio. Sensor

 

PAGES: 65
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

Materials based on metallic molybdates have attracted many studies, due to their properties leading to numerous technological applications in several areas, such as: photoluminescence, photocatalysis and gas detection sensors. In this work, we performed the synthesis of cerium molybdate (Ce2(MoO4)3) nanocrystals via the co-precipitation method followed by the microwave-assisted hydrothermal (MAH) at 150 °C during different times of synthesis (15, 30 and 60 min). This study showed that the effect of the MAH treatment time influenced the microstructural, optical and ozone gas-sensing properties. X-ray diffraction (XRD) and Raman spectroscopy measurements revealed that the samples presented a single-crystalline phase with scheelite-type tetragonal structure. Field emission gun scanning electron microscopy (FEG-SEM) images showed that MAH conditions favored changes in the morphology of the Ce2(MoO4)3 nanocrystals. In addition, transmission electron microscopy (MET) revealed that the interplanar distances corresponding to the main peak found in the XRD diffractogram, and the SAED confirmed that the samples are polycrystalline with concentric rings. The photoluminescence (PL) measurements indicated a significant increase in the PL emission with the time MAH, suggesting an increase in the intrinsic defects formed during the synthesis. The gas-sensing performance of cerium molybdate nanocrystals in relation to ozone sub-ppm levels was also investigated. The experiments revealed complete recovery and good repeatability as well as a good sensor response, which was improved in the sample synthesized in the longer time of the HMO.

BANKING MEMBERS:
Interna - 1802888 - FABIANA VILLELA DA MOTTA
Externo à Instituição - LUIS FERNANDO DA SILVA
Presidente - 1883170 - MAURICIO ROBERTO BOMIO DELMONTE