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Ab initio based description of the unusual increase of the electric field gradient with temperature at Ti sites in rutile TiO2статья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 16 декабря 2020 г.
- Авторы: Nikolaev A.V., Chtchelkatchev N.M., Bibikov A.V., Salamatin D.A., Tsvyashchenko A.V.
- Журнал: Physical Review B
- Том: 102
- Номер: 17
- Год издания: 2020
- Издательство: American Physical Society
- Местоположение издательства: United States
- Номер статьи: 174305
- DOI: 10.1103/physrevb.102.174305
- Аннотация: Combining a precise ab initio electron band structure calculation of the TiO2 rutile structure with the temperature evolution of the Ti mean-square displacements, we reproduce a puzzling temperature increase of the electric field gradient at Ti sites in TiO2, observed experimentally. Our method employs a procedure of averaging two quadrupole electron density components (L = 2) inside a sphere vibrating with the Ti nucleus at its center, where the key factor introducing the temperature dependence is the square root of the Debye-Waller factor. Although the Debye-Waller factor always reduces the corresponding Fourier component, in TiO2 due to the interplay between terms of opposite signs, itresults in a net increase of the whole sum with temperature, leading to the growth of the electric field gradient. Quantitatively, we find that the increase of electric field gradient is only half of the experimental value, which we ascribe to anharmonic effects or a strong oxygen position influence. In addition, our method reproduces the unusual temperature dependence of the asymmetry parameter eta, which first decreases with temperature, goes to zero and then increases.
- Добавил в систему: Николаев Александр Васильевич