Resumo

SANTIAGO-TEODORO, Maribel et al. Synthesis, Microstructure and EPR of CaMnO₃ and Eu_xCa_1-xMnO₃ Manganite, Obtained by Coprecipitation. J. Mex. Chem. Soc [online]. 2011, vol.55, n.4, pp.204-207. ISSN 1870-249X.

The synthesis of CaMnO₃ and Eu_xCa_1-xMnO₃ obtained by coprecipitation method is showed. The synthesized samples were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM), the powders showed orthorhombic structure and pnma space group. When it was doped with Europium, their morphology tendency was spherical. Measurements were carried out on electron paramagnetic resonance (EPR) with constant frequency = 9.4 GHz (band X) and dc magnetic field (Hdc) 0-0.8 T, measurements were at 300 K and 77 K. EPR spectra showed significant differences between both samples, indicating that the substitution of divalent alkaline earth cations by trivalent rare earth ions, allowing the formation of a mixed valence state of manganese, Mn³⁺ and Mn⁴⁺. A 77 K, the manganite of concentration x = 0.30 had a magnetic ordering, noted by the presence of hysteresis.

Palavras-chave : Synthesis; microstructure; manganite; coprecipitation; electronic paramagnetic resonance.

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