cm5b03566_si_001.pdf (1.77 MB)
Download fileSol–Gel Synthesis and Micro-Raman Characterization of ε‑Fe2O3 Micro- and Nanoparticles
dataset
posted on 2016-03-03, 15:55 authored by J. López-Sánchez, A. Serrano, A. Del Campo, M. Abuín, O. Rodríguez de la
Fuente, N. CarmonaIn this work, we present a sol–gel
synthesis of ε-Fe2O3 nano and microparticles
stabilized in silica
thin films. Thanks to the relatively high size of the synthesized
particles, we have been able to discriminate the Raman signal of the
ε- and α-Fe2O3 phases, thus presenting
the first Confocal Raman Microscopy study of isolated ε-Fe2O3 particles. The vibrational modes of each phase
are identified at room temperature. The phase transition from ε-
to α-Fe2O3 and the morphological modifications
are analyzed as a function of the in situ output laser power. A complete
study of the Raman spectra for ε-Fe2O3 particles has been performed for a wide range of temperatures (80–570
K). The phonon frequencies and line widths show a behavior in which
the contributions from lattice thermal expansion and anharmonic interactions
have to be considered. We have also identified a two-magnon mode in
the ε-Fe2O3 phase. Its intensity increases
close to the Néel transition (TN) and persists well
above it. This observation could be one of the few experimental examples
of a paramagnon, i.e., a magnetic excitation in a paramagnetic state.