Regensburg 2025 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 1: (Multi)ferroic States: From Fundamentals to Applications (I)

KFM 1.3: Talk

Monday, March 17, 2025, 10:15–10:30, H9

Unconventional Polarization Response in Titanite-type Oxides due to Hashed Antiferroelectric Domains — •Hiroki Taniguchi¹, Takumi Watanabe¹, Taro Kuwano², Akitoshi Nakano¹, Yukio Sato³, Manabu Hagiwara⁴, Hiroko Yokota², and Kazuhiko Deguchi¹ — ¹Department of Physics, Nagoya University, Nagoya, Japan — ²School of Materials and Chemical Technology, Institute of Science Tokyo, Yokohama, Japan — ³Research and Education Institute for Semiconductors and Informatics, Kumamoto University, Kumamoto, Japan — ⁴Department of Applied Chemistry, Keio University, Yokohama, Japan

CaTiSiO₅, a titanite-type oxide, consists of one-dimensional chains of TiO₆ octahedra bridged by SiO₄ tetrahedra and CaO₇ polyhedra. While CaTiSiO₅ has potential antiferroelectric properties, these have not been directly verified until now. In this study, we demonstrate the antiferroelectricity of CaTiSiO₅ by observing a double P−E hysteresis loop. Moreover, we show an unconventional enhancement of permittivity through partial substitution of Si with Ge, resulting in a doubling of permittivity over a wide temperature range in the antiferroelectric phase. Transmission electron microscopy and second harmonic generation measurements have revealed the formation of microscopic polar regions in the antiferroelectric phase of CaTi(Si₀.5Ge₀.5)O₅. Antiphase boundaries are suggested to play a role in the generation of these microscopic polar regions. This study provides new insights into boosting the permittivity of antiferroelectric materials from the perspective of domain engineering.

Keywords: Antiferroelectricity; Titanite; Domain; Phase Transition; 1 dimensional