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FM: Fachverband Funktionsmaterialien

FM 11: Poster Session Functional Materials

FM 11.27: Poster

Dienstag, 10. März 2026, 18:00–20:30, P4

Polarons in LiNb_1−xTa_xO₃ solid solutions on both sides of the Curie temperature — •Christa Fink-Bauer and Simone Sanna — Institute for Theoretical Physics, Justus-Liebig-University, Heinrich-Buff-Ring 16, 35392 Giessen, Germany

Polaronic defects in LN, LT and their solid solutions LiNb_1−xTa_xO₃ are important to understand their (electrical) conductivity. We do not only model these defects in the low-temperature ferroelectric phase, which is of great interest due to its spontaneous polarization leading to special properties as piezoelectricity, photoelasticity or nonlinear optical response, but also model the high-temprature paraelectric phase, which is stable above the Curie temperature and is of relevance for high-temperature applications. We calculate defect levels in the electronic band gap to extract activation energies for electronic transport. In addition, we calculate formation energies in pure LN and LT and their solid solutions, all from first principles using density-functional theory as implemented in VASP [1, 2]. [1] G. Kresse, J. Furthmüller, Computational Materials Science 6, 15 (1996). [2] G. Kresse, J. Furthmüller, Phys. Rev. B 54, 11169 (1996).

Keywords: Lithium Niobate; Lithium Tantalate; Density-functional theory; Polarons