RESEARCH PAPER
Synthesis and characterization of magnetite-maghemite
nanoparticles obtained by the high-energy ball milling method
A. A. Velásquez
&
C. C. Marín
&
J. P. Urquijo
Received: 25 October 2017 /Accepted: 14 February 2018 / Published online: 13 March 2018
#
Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract We present the process of synthesis and char-
acterization of magnetite-maghemite nanoparticles by
the ball milling method. The particles were synthesized
in a planetary ball mill equipped with vials and balls of
tempered steel, employing dry and wet conditions. For
dry milling, we employed microstructured analytical-
grade hematite (α-Fe
2
O
3
), while for wet milling, we
mixed hematite and deionized water. Milling products
were characterized by X-ray diffraction, transmission
electron microscopy, room temperature Mössbauer
spectroscopy, vibrating sample magnetometry, and
atomic absorption spectroscopy. The Mössbauer spec-
trum of the dry milling product was well fitted with two
sextets of hematite, while the spectrum of the wet mill-
ing product was well fitted with three sextets of spinel
phase. X-ray measurements confirmed the phases iden-
tified by Mössbauer spectroscopy in both milling
conditions and a reduction in the crystallinity of the
dry milling product. TEM measurements showed that
the products of dry milling for 100 h and wet milling for
24 h consist of aggregates of nanoparticles distributed in
size, with mean particle size of 10 and 15 nm, respec-
tively. Magnetization measurements of the wet milling
product showed little coercivity and a saturation mag-
netization around 69 emu g
−1
, characteristic of a nano-
spinel system. Atomic absorption measurements
showed that the chromium contamination in the wet
milling product is approximately two orders of magni-
tude greater than that found in the dry milling product
for 24 h, indicating that the material of the milling
bodies, liberated more widely in wet conditions, plays
an important role in the conversion hematite-spinel
phase.
Keywords Ball milling
.
Hematite to magnetite-
maghemite conversion
.
Nanoparticles
.
Mössbauer
spectroscopy
.
Transmission electron microscopy
.
Synthesis by attrition
Introduction
Iron oxides are a group of materials that have attracted
increasing attention due to their broad range of applica-
tions, such as industrial pigments (Escobar et al. 2007),
precursor for magnetic fluids, and precursor for thin
films (Feng et al. 1975), among others. Magnetite
(Fe
3
O
4
) and maghemite (γ-Fe
2
O
3
)arethemoststudied
compounds because of their high magnetic response and
J Nanopart Res (2018) 20: 72
https://doi.org/10.1007/s11051-018-4166-x
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s11051-018-4166-x) contains
supplementary material, which is available to authorized users.
A. A. Velásquez (*)
:
C. C. Marín
Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A.
3300, Medellín, Colombia
e-mail: avelas26@eafit.edu.edu.co
C. C. Marín
e-mail: cmarina2@eafit.edu.edu.co
J. P. Urquijo
Grupo de Estado Sólido, Universidad de Antioquia, A.A. 1226,
Medellín, Colombia
e-mail: jurquijo@udem.edu.co
@Phil_Robichaud
@deepthiw
@JoseServera