Regensburg 2025 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Poster

KFM 14.15: Poster

Wednesday, March 19, 2025, 17:00–18:30, P1

Phonon Properties of perovskite oxides and halides — •Mwanaidi Mauwa Namisi and Benyao Sun — Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University Bochum, Germany

Perovskite materials, which have proven useful in many areas including photovoltaics and ferroelectrics [1], are highly structurally unstable due to the dynamic nature of the metal-halide octahedra and cation off-centering. It is therefore evident that understanding the vibrational properties of these materials is crucial in their modelling and applications. Meanwhile, there is considerable research value in developing high-performance, environmentally friendly, and health-conscious lead-free ferroelectric materials [2, 3]. Particularly, BaTiO3- based lead-free perovskites have become a major research focus. However, systematic studies on BaTiO3-based superlattices combined with BaSnO3 remain scarce. Here, we investigate the phonon properties of perovskite oxides (BaSnO3) and halides (CsPbX3, (X=I, Br, Cl) and discuss the distortions, do- main structures by the anharmonicity. We also investigate how these instabilities couple with an external field and discuss the differences in the ferroelectric nature between perovskite oxides and halides. Additionally, structural optimization was performed on BaTiO3/BaSnO3 superlattices with varying Sn concentration gradients. References (1) Bergenti, I. Appl. Phys. 2022, 55, 033001. (2) Grunebohm, A., Madhura, M., Claude, E. Appl. Phys. Lett. 2015, 107,102901. (3) Grunebohm, A.; Marathe, M. Phys. Rev. Mat. 2020, 4,4417.

Keywords: Perovskites; Ferroelectricity; Phonon instyabilities; Octahedral tilting; Electrocalorics