Ageing Phenomena in La-Sr Manganites with Divalent Substituents for Manganese

D. Merkulova, A. Badelina, S. Estemirovab and V. Karpasyuka a Astrakhan State University, Tatishchev str. 20a, 414056 Astrakhan, Russia b Institute for Metallurgy, UB Russian Academy of Sciences, Amundsen str. 101, 620016 Yekaterinburg, Russia

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Variations of electromagnetic and structural characteristics of La1-c+xSrc-xMn1-xMexO3+γ manganites (Me = Zn, Ni) during storage time up to 36000 hours at room temperature and after frequentative thermal cycling in the 300-573 K range were investigated. Changes of magnetization of all samples were within the error of measurement. In most cases Curie point (TC) showed irregular variations within the range of 20%, while zinc-substituted manganites with relatively high values of "c" exhibited some trend of TC rise. The resistance of all samples increased during storage period. The cell volume of single-phase manganites decreased over time, that may indicates an increase in oxygen content. However, the sample with the highest Ni content (x=0.125) at c=0.19 suffered phase transition "rhombohedral-orthorhombic structures", which cannot be explained by the oxygen absorption. Probably, this effect was due to the rearrangement of the ions and vacancies between crystal sublattices of manganite.

DOI: 10.12693/APhysPolA.133.529 PACS numbers: 75.30.-m, 75.47.-m, 75.47.Lx, 81.70.-q