Probe Mössbauer Diagnostics of Charge Ordering in Manganites CaCuxMn7–xO12 (0 ≤ x ≤ 1).

Autor: Glazkova, I. S., Rusakov, V. S., Sobolev, A. V., Matsnev, M. E., Gapochka, A. M., Gubaidulina, T. V., Presniakov, I. A.
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Zdroj: Journal of Experimental & Theoretical Physics; Dec2019, Vol. 129 Issue 6, p1017-1028, 12p
Abstrakt: We present the results of our 57Fe probe Mössbauer study in manganites CaCuxMn6.96–x57Fe0.04O12 (0 ≤ x ≤ 1). We have established that for compositions 0 ≤ x ≤ 0.15 near the structural R ↔ Im transition (at T ≈ TCO), an increase in the temperature leads to a decrease in the content of the rhombohedral phase (R ) against a background of the "nucleation" and gradual increase in the fraction of the cubic phase (Im ), in which all octahedral positions of manganese are equivalent due to the electron exchange Mn3+ ↔ Mn4+. The increase in the electron exchange frequency is assumed to be related to a weakening of the electron–lattice interaction of Jahn–Teller Mn3+ cations as x → 0.4. An increase in the copper content leads to a sharp decrease in the phase transition temperature TCO. A single component corresponding to the cubic phase (Im ) is present in the spectrum starting from x ≥ 0.4. Based on our Mössbauer data, we have constructed a T–x phase diagram. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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