Banca de DEFESA: LUCAS MARQUES DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUCAS MARQUES DA SILVA
DATA : 06/04/2018
HORA: 15:00
LOCAL: AUDITÓRIO DO DFTE
TÍTULO:

Synthesis, structural and magnetic characterization of barium hexaferrites doped with La³⁺ and Co²⁺

PALAVRAS-CHAVES:

Hexaferrites doped, nanoparticles, rare earth, chitosan, magnetic properties,

Hopkinson effect.

PÁGINAS: 70
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:

The barium hexaferrite, an iron oxide of hexagonal geometry, currently plays an important technological role in applications such as permanent magnets, microwave devices, and magnetic recording. In this work, we investigated the effects of doping with La³⁺ and Co²⁺ ions on the magnetic and structural properties of barium hexaferrite. Two series of samples were produced, Ba_1-αLa_αFe_12-xCo_xO₁₉ with α=0.30, x=(0.0, 0.25, 0.50, 0.75, and 1.0) and α=0.10, x=(0.25 and 0.50). The samples were synthesized by the Ionic Coordination Reaction technique in chitosan polymer matrix and calcined in air 900 °C/4 h. The characterization was performed by X-ray diffractometry, scanning electron microscopy, vibrating sample magnetometry, Mössbauer spectroscopy and physical properties measurement system. The X-ray diffractograms revealed the presence of the BaFe₁₂O₁₉ type crystalline phase in all samples, with mean particle size ranging from 71 - 58 nm, decreasing with doping. The electron micrographs presented a particle morphology in the form of nanorods and nanoplates, with lengths and diameters varying around 190 nm and 70 nm, respectively. The analysis detected impurities of α-Fe₂O₃ and γ-Fe₂O₃, for the series with α=0.30. 

MEMBROS DA BANCA:
Presidente - 350830 - JOSE HUMBERTO DE ARAUJO
Externo à Instituição - JOÃO MARIA SOARES - UERN
Interno - 1675199 - SUZANA NOBREGA DE MEDEIROS