|
ИСТИНА |
Войти в систему Регистрация |
Интеллектуальная Система Тематического Исследования НАукометрических данных |
||
The Interrelation between Iron Valence and Oxygen Vacancies in Substituted Orthoferrite La0.67Sr0.33FeO3−γ during Heat Treatmentстатья
- Авторы: Sedykh V.D., Rusakov V.S., Gubaidulina T.V., Rybchenko O.G., Kulakov V.I.
- Журнал: Physics of Metals and Metallography
- Том: 124
- Номер: 2
- Год издания: 2023
- Издательство: Pleiades Publishing, Inc.
- Местоположение издательства: New York, USA
- Первая страница: 153
- Последняя страница: 160
- DOI: 10.1134/S0031918X22601950
- Аннотация: In this paper, we studied substituted lanthanum orthoferrite La0.67Sr0.33FeO3 – γ by Mössbauer spectroscopy using X-ray diffraction data. A series of vacuum annealing was performed in the temperature range of tann = 200–650°C, during which no significant changes in the structure of the samples were detected. The Mössbauer measurements at room temperature show that the Fe ions are in an average valence state between Fe3+ and Fe4+. During vacuum annealing, as the temperature tann increased, the average hyperfine magnetic field on the 57Fe nuclei and the isomeric shift of the spectrum increased, which is associated with an increase in the number of vacancies and, accordingly, a decrease in the amount of Fe4+. Mössbauer measurements at 85 K showed that the average valence state of iron does not manifest itself. The hyperfine parameters of the partial low-temperature Mössbauer spectra obtained from the model interpretation indicate that one of them belongs to Fe4+ ions, and the rest belong to Fe3+. The presence in the spectra of several sextets related to Fe3+ ions is due to the appearance of oxygen vacancies (breaking of the Fe3+–O2––Fe exchange bond) and Fe4+ ions (weakening of the Fe3+–O2––Fe exchange bond) in the nearest ionic environment of Fe atoms. Both factors cause a decrease in the hyperfine magnetic field and a change in the isomeric shift of the spectrum. As a result of model interpretation of the Mössbauer spectra, the numbers of oxygen vacancies and Fe4+ ions per formula unit were determined for all samples depending on vacuum annealing temperature tann. It was shown that at tann above 450°C the process of oxygen leaving the lattice ends and only Fe3+ ions are detected.
- Добавил в систему: Русаков Вячеслав Серафимович