Mössbauer study of BiFe0.95Ni0.05O3тезисы доклада

Дата последнего поиска статьи во внешних источниках: 27 января 2018 г.

Работа с тезисами доклада

[1] Mössbauer study of bife0.95ni0.05o3 / K. V. Kulakov, V. S. Rusakov, A. A. Belik et al. // International Conference on the Applications of the Mössbauer Effect - ICAME 2017. Conference Programme and Book of Abstracts. — Aising St.Petersburg, 2017. — P. 128–128. The spatial spin-modulated structure (SSMS) and hyperfine interactions in BiFe0.95Ni0.05O3 were studied in the temperature range including the magnetic ordering temperature using 57Fe Mossbauer spectroscopy. It was found that in the first cationic coordination sphere of iron atoms there were one or two Ni atoms. At the same time, Ni atoms were distributed randomly over the positions of Fe atoms in the BiFeO3 structure. Below the magnetic ordering temperature the formation of an incommensurate anharmonic SSMS of the cycloid type in which iron atoms with different cationic environments participated was detected. The Mossbauer spectra have been analyzed in terms of the incommensurate anharmonic SSMS of cycloid type model. As a result, the temperature dependences of the SSMS anharmonicity parameter and the parameters of hyperfine interactions were obtained. These dependencies indicated that the transition from the magnetic anisotropy of the easy axis type to the easy plane type occurred at the temperature ∼460 K. At low temperatures a significant increase in the anharmonicity parameter (by 0.30.4) was observed in comparison with BiFeO3. The temperature dependences of the isotropic contribution to the hyperfine magnetic field at low temperatures were processed in the framework of the spin wave model, at temperatures close to the Neel temperature – using the similarity theory, and over the entire temperature range – by the effective molecular field model. As a result, the parameters and critical indexes of the models were determined. The anisotropic contribution first increased slightly (from 5 K) with increasing temperature, and then decreased (after ∼460 K) tending to zero at ∼580 K. It was established that the replacement of the Fe atom by the Ni atom in the nearest cationic environment of the Fe atom lead to a decrease in the isotropic contribution to the hyperfine magnetic field (by 1020 kOe), and this change increased with temperature rise. Subsequent substitutions by an impurity atom lead to a greater decrease in the isotropic contribution. With such substitutions, there were no noticeable changes in the other hyperfine parameters: the anisotropic contribution, the isomer shift and the quadrupole shift of the resonance lines.

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