INVESTIGADORES
SANCHEZ Rodolfo Daniel
congresos y reuniones científicas
Título:
Magnetic and electric transport properties of LaFe0.5Co0.5O3 perovskite system: effect of annealing temperature
Autor/es:
C. A. LÓPEZ; J. LOHR; M.E. SALETA; J CURIALE; RODOLFO D. SÁNCHEZ
Lugar:
Barcelona
Reunión:
Conferencia; 20Th International Conference on Magnetism ICM2015; 2015
Institución organizadora:
ICM2015 Organizing Comitee
Resumen:
The perovskite-like compound LaFe0.5Co0.5O3
have attracted significant attention for more than a decade, mainly
because of their magnetoelectric and multiferroic properties.[1,2] In
this work we present the synthesis, structure, magnetism and electric
transport properties of different grain size LaFe0.5Co0.5O3 perovskites.
Different compounds have been synthesized by citrate method and then
annealed 12 hours at different temperatures (Ta) between 873 and 1473 K.
The crystallographic characterization was performed by X-ray powder
diffraction, the best Rietveld refinement was obtained with a
rhombohedral structure (R-3c) at room temperature. Also from the X-ray
data, we observe the increase of the grain size increasing Ta. The
temperature and field dependence of the magnetization evidences a
ferrimagnetic transition (Tc) around 250 K in all cases. Differences in
field cooled cooling, field cooled warming and zero-field cooled
magnetization suggest the presence of different magnetic states (Ferri
and Antiferro) below Tc whose ratio change with temperature. Impedance
and DC resistivity were characterized as a function of temperature. The
resistivity shows a semiconducting-like or thermally activated behavior.
From impedance spectroscopy (IS) characterization, we calculated
different complex functio
ns as: impedance (Z*), dielectric modulus (M*), permittivity (ε*); and
loss tangent (tan δ). The conduction process is dominated by a
long-range mechanism in all samples. This process is related to a single
relaxations peak in tan δ plots. However, imaginary part of Z* and M*
functions show two different relaxations process, which are linked to
the grain and grain boundary effects. From this behavior we found the
increase of the grain boundary effect as the Tal decreases. On the other
hand, we observed a subtle effect of Ta on the studied magnetic
properties. However, differences on the contact between ceramic grains
becomes much more important on the transport properties (IS and DC
resistivity). As a final remark, our work shows how the synthesis
protocol is a powerful tool in the search of specific properties of
these kinds of oxides.
[1] Fiebig, et al. Nature (London, U.K.) 2002, 419, 818−820.
[2] Kimura, T., et al. Nature (London, U.K.) 2003, 426, 55−58