Banca de DEFESA: VITÓRIA CHRIS SOUZA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : VITÓRIA CHRIS SOUZA SILVA
DATA : 14/07/2022
HORA: 14:00
LOCAL: Sala da Pós-Graduação Física Uern
TÍTULO:

Structural, magnetic and optical characterization of Silenita Bi₂₅FeO^₄₀ doped with Mn obtained via solid state reaction using minerals.

PALAVRAS-CHAVES:

Keywords: Minerals, Doping, Silenite (Bi25F eO40).

PÁGINAS: 123
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física da Matéria Condensada
ESPECIALIDADE: Materiais Magnéticos e Propriedades Magnéticas
RESUMO:

Samples with silenite structure of the type Bi25F eO40 doped with manganese (Mn) were produced via solid state reaction, at a temperature of 700◦C, using bismuth ores as precursors, iron and manganese extracted from deposits located in the state of Rio Grande do Norte. The X-ray diffractograms obtained for the specimens confirm the presence of the Bi₂₅FeO₄₀ phase and the BiClO₂Pb spurious phase, in which the former has a weight percentage greater than 90% . Hysteresis curves at room temperature indicate an increase in the coercive field and a decrease in the remanent magnetization with the increase in the concentration of dopant ions in the crystal structure, which may result from a possible contribution of distinct magnetic phases. The values of g factor obtained in the Electronic Paramagnetic Resonance spectra point to resonance signals coming from paramagnetic centers of Fe3+ ions. The band gap energies were calculated for each sample through the absorbance values obtained by UV/Visible Spectrometry and the results varied between 2.24 and 2.27 eV, which indicates that the compounds have potential for applications in photocatalytic activities. Zeta potential analyzes were performed for samples Bi₂₅FeO₄₀, subjected to heat treatment at a temperature of 600 ^oC, and Bi₂₅Fe_(1−x)Mn_xO₄₀ (BMO), with x = 1, calcined at 700◦C, in order to estimate the surface charge of the particles and later apply them in the process of drug adsorption. For a pH of 6.8, the samples exhibited a net negative charge. In the adsorption, the BMO sample showed a better efficiency in removing the drug from the solution.

Keywords: Minerals, Doping, Silenite (Bi25F eO40).

MEMBROS DA BANCA:
Presidente - 7958 - JOSÉ ALZAMIR PEREIRA DA COSTA
Interno - 4260 - JOÃO MARIA SOARES
Externo à Instituição - ISAAC BARROS TAVARES DA SILVA