Banca de DEFESA: CAIQUE DIEGO DE ABREU LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE: CAIQUE DIEGO DE ABREU LIMA
DATA: 29/07/2021
HORA: 14:30
LOCAL: Plataforma Google Meet
TÍTULO: Microbastões Hierárquicos de α-MoO 3 :xCo: Síntese, Estrutura e Propriedades Fônicas.
PALAVRAS-CHAVES: α-MoO 3 ; Alta temperatura; Espectroscopia Raman; Microcristal.
PÁGINAS: 47
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:

We present a study on the structural and phonon properties of cobalt-doped
orthorhombic molybdenum trioxide (α-MoO 3 :xCo) hierarchical microrods. The samples
were synthesized by solid-state reaction with molar concentrations of 0%, 1%, 3%, and,
5% cobalt. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy
(SEM), and Fourier transformed infrared spectroscopy (FTIR) were used to confirm the
orthorhombic phase and the structural properties of each sample. The infrared and Raman
spectra of the samples show that doping alters the ratio of relative intensities, linewidth,
and the shift of the wavenumber of the modes, and a correlation is established between the
stretching force constant and wavenumber. Experimental temperature-dependent Raman
scattering studies were performed on samples of α-MoO 3 :xCo over a temperature range of
298–813 K. The Raman spectra showed a phase transition at around 373 K to a self-
similar structure, indicating a possible isostructural phase transition (IPT) for samples with
0% and 1% cobalt, a phenomenon rarely reported in the literature. Nevertheless, this phase
transition was not observed for samples containing 3% and 5% cobalt, indicating an
increase in material stability.

MEMBROS DA BANCA:
Presidente - 2056226 - CLEANIO DA LUZ LIMA
Interno - 1720015 - GARDENIA DE SOUSA PINHEIRO
Externo ao Programa - 048.317.544-71 - GUSTAVO OLIVEIRA DE MEIRA GUSMÃO - UESPI
Externo à Instituição - JOAO VICTOR BARBOSA MOURA - UFMA