Resumo de eventos cient??ficos
Structural and magnetic properties of CeO2 nanomaterials as a function of different morphologies
Autor
SOUZA, JULIANA P. de
SERNA, JILDER D.P.
MORAES, LETICIA P.R. de
SILVA, JULIO C.M.
ALVES, ODIVALDO C.
BRAZIL MRS MEETING, 19th; INTERNATIONAL UNION OF MATERIALS RESEARCH SOCIETIES - INTERNATIONAL CONFERENCE ON ELECTRONIC MATERIALS
Resumen
The nanomaterials of cerium oxide can be applied in catalysts, fuel cells and spintronics [1].
Additionally, in its crystalline structure, small defects named oxygen gaps appear, caused by
its high potential pattern of reduction from Ce IV to Ce III or that it becomes an oxidizing
agent and the conferring agent. In this work we investigated the magnetic properties of
three ceria morphologies on a nanometric scale: nanocubes, nanowires and nanobelt that
were synthesized using the hydrothermal method. As samples prepared from studies by
using X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetometry
(VSM) and paramagnetic resonance (EPR). XRD measurements show characteristic peaks of
ceria fluorite face-centered cubic structure. Measurements of magnetization in function of
the field applied at room temperature showing the ferromagnetic character with different
values of the coercive field and saturation magnetization, we observe an increase in the
coercive field and saturation magnetization in ceria nanocubes that can be explained by an
increase in the density of vacancy [2]. The zero field cooled (ZFC) and field cooled (FC)
magnetization curves measured on low magnetic fields show a soft maximum around 60 K
attributed to oxygen at the sample surface. Applying to the Curie-Weiss equation indicates
the presence of antiferromagnetic interactions mainly in nanobelt and nanocubes
morphologies. The EPR spectra at room temperature show two paramagnetic symmetry,
with axial symmetry with g1 = 1.97 and g2 = 1.94 associated with Ce 3+ and another isotropic
around g = 2.03 due to vacancies of isolated oxygen for all samples. The ferromagnetic
arrangement characterized by the presence of broad signals at about 3500 G is also
observed in nanobelt morphologies. Conselho Nacional de Desenvolvimento Cient??fico e Tecnol??gico (CNPq) Funda????o de Amparo ?? Pesquisa do Estado do Rio de Janeiro (FAPERJ) CNPq: 422614/2018-1 FAPERJ: E-26/211371/2019