Physical properties of Sr2FeIrO6 and Sr1.2La0.8FeIrO6 double perovskites obtained by a new synthesis route
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2016
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Previous works on Sr2-xLaxFeIrO6 double perovskite (DP) series reported a possible ferromagnetic transition at T ~ 700 K for the x ¼ 0.8 concentration, for which was observed the presence of spurious Fe2O3
phase. In order to prevent the formation of this impurity phase and check if this high temperature
magnetic transition is intrinsic of the material, different synthesis routes became necessary. In this work,
polycrystalline samples of Sr2-xLaxFeIrO6 (x ¼ 0.0 and 0.8) have been synthesized by solid state reaction
using a new heating treatment. The sample's properties were investigated by synchrotron x-ray powder
diffraction (SXRD), transmission electron microscopy (TEM), magnetic susceptibility, specific heat and
electrical resistivity, and compared with the previously reported results. The SXRD data revealed a
structural transition induced by La to Sr substitution (I2/m4P21/n). Moreover, it was not detected the
presence of Fe2O3 on the samples obtained by the new route, which might be related to the absence of
high temperature magnetic ordering. The magnetometry results indicated the emergence of Ir4þ with La
doping, being corroborated by specific heat measurements which suggest Fe3þ/Ir5þ and Fe3þ/Ir4þ configurations for x ¼ 0.0 and 0.8 compounds, respectively. Temperature dependent electrical resistivity
measurements showed that Sr2þ to La3þ substitution leads to a decrease of electrical resistivity, possibly
associated with the increase in the number of Ir valence electrons.
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Magnetic materials, Heat treatment, Crystal structure, Magnetic properties, Electrical properties, Specific heat
Citação
BUFAIÇAL, Leandro et al. Physical properties of Sr2FeIrO6 and Sr1.2La0.8FeIrO6 double perovskites obtained by a new synthesis route. Materials Chemistry and Physics, Amsterdam, v. 182, p. 459-465, 2016. DOI: 10.1016/j.matchemphys.2016.07.057. Disponível em: https://www.sciencedirect.com/science/article/pii/S0254058416305776. Acesso em: 16 fev. 2024.