Homogeneity regions of neodymium,samarium, and europium manganites in air |
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Authors: | O M Fedorova V F Balakirev Yu V Golikov |
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Institution: | (1) Institute of Metallurgy, Ural Division, Russian Academy of Sciences, ul. Amundsena 101, Yekaterinburg, 620016, Russia |
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Abstract: | XRD phase analysis of homogeneous phases and heterogeneous compositions of general formula Ln2?x MnxO3±δ (Ln = Nd, Sm, Eu; 0.90 ≤ x ≤ 1.20; Δx = 0.22) prepared by ceramic synthesis from oxides in air at 900–1400°C was used to determine the solubility boundaries for Ln2O3 oxides and maganese oxides in LnMnO3±δ. The results were represented as fragments of the phase diagrams for the Ln-Mn-O systems in air. It was assumed that the solubility of Ln2O3 oxides in LnMnO3±δ is determined by lattice defects, while that of manganese oxides, in addition to above mechanism, by the disproportionation reaction 2Mn3+ = Mn2+ + Mn4+ followed by the partial substitution of divalent magnesium for Ln3+ at cuboctahedral positions of the perovskitelike crystal lattice. |
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