@Article{PintoMachGomeReze:2019:InMoSt,
author = "Pinto, Simone de Souza and Machado, Jo{\~a}o Paulo Barros and
Gomes, Newton A. S. and Rezende, Mirabel Cerqueira",
affiliation = "{Universidade Federal de S{\~a}o Paulo (UNIFESP)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Tecnol{\'o}gico de Aeron{\'a}utica (ITA)} and {Universidade
Federal de S{\~a}o Paulo (UNIFESP)}",
title = "The influence of morphology, structure, and weight fraction of
magnetic additives on the electromagnetic characteristics of
composites",
journal = "Journal of Magnetism and Magnetic Materials",
year = "2019",
volume = "484",
pages = "126--138",
month = "Ago",
keywords = "Magnetic additives, Composites, Microwave absorber, Shielding
effectiveness, Reflectivity.",
abstract = "This study deals with different magnetic additives based on
ferrites (MnZn, LaCa (Co and Ti)), carbonyl iron (CI), and iron
filaments (IF) formulated in epoxy resin. Morphological and
structural characteristics of the additives were evaluated. Based
on these additives samples with both different thickness and
weight fractions (170 wt%) were prepared. The formulated
composites were analyzed considering different electromagnetic
characteristics: reflectivity, shielding effectiveness, the
complex parameters of dielectric permittivity (\ε) and
magnetic permeability (µ), and the corresponding loss tangents in
the microwave X-band. Scanning electron microscopy assisted with
energy-dispersive spectrometry (SEM-EDS) analyses show that the
additives have different morphologies, with varied sizes, shapes,
and compositions. X-ray diffraction (XRD) analyses allowed
determining the structural phases of the magnetic additives: CI
and IF are constituted by Fe-\α phase, the ferrite of MnZn
has an unique phase, and the two ferrites of LaCa-Co and LaCa-Ti
have the same phase in the presence of different metallic oxides.
In general, the complex parameters of \ε and µ increased
with the additive concentration increase in the composites, as
expected, considering the magnetic characteristics of all
additives studied. Reflectivity measurements show different
attenuation values with promising results for composites based on
CI, IF, and MnZn ferrite. The composites based on the ferrites
show the worst performance on the reflectivity measurements. The
shielding effectiveness measurements show good results (20 dB)
over the entire X-band for specimens based on the LaCa-Co ferrite.
In this case, the dominant shielding mechanism is due to the
multiple scattering (SEM) in the material.",
doi = "10.1016/j.jmmm.2019.03.085",
url = "http://dx.doi.org/10.1016/j.jmmm.2019.03.085",
issn = "0304-8853",
language = "en",
targetfile = "souza_influence.pdf",
urlaccessdate = "27 abr. 2024"
}