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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 15: Postersession KFM

KFM 15.1: Poster

Donnerstag, 19. März 2020, 16:00–18:30, P2/1OG

Defect physics in LiTaO₃ — •Mike N. Piontek and Simone Sanna — Insitut für Theoretische Physik und Center for Materials Research, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany

While the defect physics of LiNbO₃ has been object of many investigations, the nature of point defects in the isomorphic and isoelectronic LiTaO₃ is much less known. Although the existence of small bound polarons [1,2] in LiTaO₃ might be expected due to the high lattice polarizability, the verification of this assumption is still missing. In this work we provide the atomistic description of small bound polarons Ta_Li^5+/4+ in LiTaO₃ and of many other point defects such as Ta and Li vacancies. The calculations performed within density functional theory with Hubbard corrections predict the large lattice relaxation of the oxygen ligands associated to the electronic capture at the antisite center, which can be interpreted as due to the polaron formation. The relative formation energies of the investigated defects closely mirror those of corresponding defects in LiNbO₃ [3], suggesting a rather similar defect physics in the two materials. [1] O. F. Schirmer et al., J. Phys.: Condens. Matter 21, 123201 (2009). [2] F. Freytag et al., Nature Scientific Reports 6, 36929 (2016). [3] Y. Li, W. G. Schmidt, S, Sanna, Phys. Rev. B 89, 094111 (2014).