Publication:
Ab initio based description of the unusual increase of the electric field gradient with temperature at Ti sites in rutile TiO2

Дата
2020
Авторы
Chtchelkatchev, N. M.
Salamatin, D. A.
Tsvyashchenko, A. V.
Nikolaev, A. V.
Bibikov, A. V.
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Научные группы
Организационные подразделения
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Институт лазерных и плазменных технологий
Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.
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Аннотация
© 2020 American Physical Society.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, it results 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 η, which first decreases with temperature, goes to zero, and then increases.
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Ab initio based description of the unusual increase of the electric field gradient with temperature at Ti sites in rutile TiO2 / Chtchelkatchev, N.M. [et al.] // Physical Review B. - 2020. - 102. - № 17. - 10.1103/PhysRevB.102.174305
URI
https://www.doi.org/10.1103/PhysRevB.102.174305
 https://www.scopus.com/record/display.uri?eid=2-s2.0-85096141191&origin=resultslist
 http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=WOS_CPL&DestLinkType=FullRecord&UT=WOS:000587484900003
 https://openrepository.mephi.ru/handle/123456789/22574
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