Berlin 2024 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 9: KFM Poster Session

KFM 9.12: Poster

Monday, March 18, 2024, 18:00–20:00, Poster E

Investigation of intrinsic defect formation energies in lithium niobate-tantalate solid solutions. — •Nils Andre Schäfer and Simone Sanna — Institute for Theoretical Physics, Justus Liebig University Giessen, Germany

The optical response of LiNbO₃ (LN) and LiTaO₃ (LT) is influenced, among other properties, by intrinsic defects. In particular, spectroscopic signatures of quasiparticles known as polarons are an hallmark of LN and LT, respectively. Unfortunately, very little is known about the intrinsic defects in LiNb_1−xTa_xO₃ solid solutions (LNT), which are employed to tune the materials properties by composition. In order to improve our understanding of the defect structure in LNT, we model different microscopic realizations of small bound polarons, bipolarons as well as lithium vacancies.

We systematically explore changes in the formation energy of microscopic polaronic structures across varying concentrations of LNT. Additionally, we investigate the existence of a preferred positions of these defects within LNT. Our atomistic calculations were carried out using the DFT+U method as implemented in VASP.

Keywords: lithium niobate; lithium tantalate; polarons; LNT solid solution