Banca de DEFESA: JOSÉ JAYSON XAVIER DE SOUSA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSÉ JAYSON XAVIER DE SOUSA
DATE: 13/04/2022
TIME: 09:00
LOCAL: Plataforma Google Meet
TITLE:

CoFe₂O₄@BiFeO₃ Nanoparticles: Synthesis, Characterization and Signatures of Spin Disorder

KEY WORDS:

Ferritas, Perovskitas, Núcleo@Casca, Desordem de Spin

PAGES: 139
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

Nanoscale magnetic systems, such as ferrites, perovskites and core@shell structures, are a group of promising materials, due to their vast technological potential and the possibility of advancing the understanding of fundamental physics related to nanoscale materials. Taking this into account, we synthesize CoFe₂O₄@BiFeO₃ core/shell nanoparticles by coprecipitation and systematically investigate the structural, morphological, and magnetic properties in such nanostructured system. Through structural and morphological characterization, we demonstrate the obtainment of core@shell nanostructure with pure phases. By performing a broad experimental magnetic analysis, we evaluate the magnetic response for the precursor phases, as well as for the core@shell nanostructure. For this latter, we identify fingerprints of the wasp-waisted behavior and exchange bias effect, disclosing the exchange coupling between the phases taking place at the interface. Further, we reveal the exchange coupling between core and shell is strongly affected by a spin glass behavior arisen from the spin disorder in the CoFe₂O₄@BiFeO₃ core/shell nanoparticles. After all, our findings allow us to place the used procedures taking into account the processes of adapted coprecipitation and calcination as a feasible route to the production of high-quality core@shell nanostructures. However, in order not to be bound by a single method, core@shell samples CoFe₂O₄@BiFeO₃ with three core sizes and their precursors were synthesized through hydrothermal synthesis. This second set of samples also showed promising results, as the material obtained showed pure phases for all samples and strong indications of magnetic coupling between the phases that make up the core and the shell, indicating great efficiency of the hydrothermal method.

BANKING MEMBERS:
Interno - 1345774 - CLAUDIONOR GOMES BEZERRA
Presidente - 1508681 - FELIPE BOHN
Externo à Instituição - FERNANDO LUIS DE ARAUJO MACHADO - UFPE
Externo à Instituição - JOÃO MARIA SOARES - UERN
Interno - 1674707 - MARCO ANTONIO MORALES TORRES
Interno - 050.025.724-80 - RODOLFO BEZERRA DA SILVA - UERN