Banca de DEFESA: JOSÉ DIEGO SILVA GOMES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : JOSÉ DIEGO SILVA GOMES
DATA : 31/08/2022
HORA: 15:00
LOCAL: Sintese, Propriedades Estruturais, Ópticas e Magnéticas da Silenita de Ferro (Bi25FeO40) pura e dopa
TÍTULO:

Synthesis, Structural, Optical and Magnetic Properties of Iron Silenite (Bi25FeO40) pure and doped with cobalt
Summary

PALAVRAS-CHAVES:

Keywords: Iron Silenite, Properties, Magnetic, Doping.

PÁGINAS: 92
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física da Matéria Condensada
ESPECIALIDADE: Materiais Magnéticos e Propriedades Magnéticas
RESUMO:

 

 

In this work, samples of Iron Silenite (Bi25FeO40) pure and doped with cobalt (Co) were synthesized through two chemical routes: co-precipitation and reaction by ionic coordination (ICR), and thermally treated at a temperature of 700 °C for 2 h. The structural, optical and magnetic properties of the samples were characterized by X-ray diffractometer (XRD), UV-visible absorption spectroscopy (UV-vis) and vibrating sample magnetometer (VSM). The diffractograms (XRD) obtained for the specimens confirm the presence of the Bi25FeO40 phase with a satisfactory degree of purity, obtained by Rietveld refinement using the MAUD software, revealing a Body Centered Cubic (BCC) crystal structure with an I23 space group, a lattice parameter of 10.11 ~ 10.21 Å and particle sizes in the range of 70 ~ 182 nm. Magnetic characterization (VSM) showed a weak ferromagnetic behavior at room temperature, where hysteresis curves indicate an increase in the coercive field (HC), saturation magnetization (MS) and remanence (MR) for the doped samples, as it increases the ion concentration of the dopant. However, when compared the pure samples revealed a decrease for the parameters MS and MR, with the exception of the sample doped with 50% via co-precipitation that reveals an increase in its MS. The optical characterization showed a variation of the optical gap in the range of 1.66 ~ 2.43 eV of Bi25FeO40, through the absorbance values obtained by UV/Visible Spectrometry, revealing a decrease in band gap energies with the degree of concentration of the used, indicating a structure with great efficiency in the absorption of visible light and potential for applications in photocatalytic activities.
Keywords: Iron Silenite, Properties, Magnetic, Doping.

MEMBROS DA BANCA:
Presidente - 7958 - JOSÉ ALZAMIR PEREIRA DA COSTA
Interno - 050.025.724-80 - RODOLFO BEZERRA DA SILVA - UERN
Externo à Instituição - FRANCISCO HOLANDA SOARES JÚNIOR