Homogeneity range of neodymium manganite in air |
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Authors: | O M Fedorova V F Balakirev S Kh Estemirova Yu V Golikov |
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Institution: | (1) Institute of Metallurgy, Ural Division, Russian Academy of Sciences, Yekaterinburg, Russia |
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Abstract: | The solubility boundaries for Nd2O3 and manganese oxides in NdMnO3 ± δ have been determined by X-ray powder diffraction analysis of homogeneous phases and heterogeneous compositions of the general formula Nd2 ? x Mn x O3 ± δ (0.90 ≤ x ≤ 1.20; Δx = 0.02) prepared by ceramic technology from constituent oxides in air in the temperature range 900–1400°C. The results are presented in the form of a fragment of the Nd-Mn-O phase diagram in air. It is suggested that the Nd2O3 solubility in NdMnO3 ± δ is due to crystal defects and the solubility of manganese oxides is in addition due to the disproportionation reaction 2Mn3+ = Mn2+ + Mn4+ and the subsequent partial substitution of divalent for tervalent manganese ions in the cuboctahedral positions of the perovskite-like crystal lattice. To verify this suggestion, it is necessary to systematically study the oxygen nonstoichiometry δ in Nd2 ? x Mn x O3 ± δ as a function of x and synthesis temperature and structurally study this oxide with these parameters being varied. |
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