Banca de QUALIFICAÇÃO: JULIANI PENHA CALAND

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE: JULIANI PENHA CALAND
DATA: 27/08/2020
HORA: 09:30
LOCAL: Remota - Plataforma Google Meet
TÍTULO: Estados de oxidação e sítios de ocupação de íons Fe e Ni na estrutura cristalina do Y3Fe5O12.
PALAVRAS-CHAVES: YIG, Sol-gel, Mössbauer, XPS.
PÁGINAS: 27
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:

In this work, we study nanoparticles of YIG doped with Ni using the sol-gel method.
Preliminary analyzes were performed to confirm the formation of the phase and the presence of
the crystalline structure of the YIG. For a detailed study of the Ni ion occupation site and the Fe
ion oxidation states, measurements were realized using Transmission Electron Microscopy
(TEM), X-Ray Photoelectron Spectroscopy (XPS), Mössbauer Spectroscopy and Espectroscopy
Paramagnetic Resonance (EPR). Transmission electron microscopy showed that the
morphology has irregular shapes and clusters of nanoparticles. The electron diffraction of the
selected area (SAED) showed bright spots and diffuse rings characteristic of well-defined
crystals that support the presence of fine variations. XPS analysis contributed to evidence the
presence of Fe 2 + , Fe 3 + , Ni 2 + and oxygen vacancies. Mössbauer spectroscopy indicates the
presence of ions Fe with 2+ and 3+, and confirmed the presence of Ni in the octahedral site and
tetrahedral site locations equally. The Electron paramagnetic resonance (EPR) results confirmed
the inclusion of Ni in the Fe sites and an increase in the g factor for the doped YIG sampleThis
work contributed to the understanding the effect of addition of Ni in the iron and Yttrium Iron
Garnet, being of great importance for future applications in spintronics.

MEMBROS DA BANCA:
Interno - 1570906 - BARTOLOMEU CRUZ VIANA NETO
Presidente - 1780191 - FRANCISCO ERONI PAZ DOS SANTOS
Externo ao Programa - 704.608.714-80 - RAMON RAUDEL PEÑA GARCIA - UFPI
Interno - 1650556 - TAYRONI FRANCISCO DE ALENCAR ALVES
Externo ao Programa - 705.832.924-96 - YUSET GUERRA DAVILA - UFPE