Anion-mediated unusual enhancement of negative thermal expansion in the oxyfluoride of PbTiO<sub>3</sub>

Materials featuring negative thermal expansion (NTE) properties are crucial for controlling overall thermal expansion. However, only a limited number of NTE materials are suitable as high-performance thermal expansion compensators owing to their small NTE magnitude and narrow NTE temperature range. PbTiO<sub>3</sub> is a typical perovskite-type (ABO<sub>3</sub>) ferroelectric that also exhibits a unique NTE. While an enhanced NTE compared to pristine PbTiO<sub>3</sub> can be achieved in PbTiO<sub>3</sub>-based ferroelectrics by improving their tetragonality <i>via</i> chemical substitutions at the A/B sites, the effect of anion substitution on the thermal expansion properties of PbTiO<sub>3</sub> has rarely been studied. Here, we report an oxyfluoride of PbTiO<sub>3</sub>, as an O<sup>2-</sup>/F<sup>-</sup> solid solution with fluorine concentrations up to 10%, where PbTiO<sub>3-<i>x</i></sub>F<sub><i>x</i></sub> demonstrated a reduced tetragonality as a function of fluorine. Notably, for the first time, we observed a reduced tetragonality accompanied by an unusually enhanced NTE in the present PbTiO<sub>3-<i>x</i></sub>F<sub><i>x</i></sub> of PbTiO<sub>3</sub>-based ferroelectrics, contrary to the previously reported enhanced NTE in PbTiO<sub>3</sub>-based ferroelectrics. This unconventional phenomenon can be sufficiently understood considering the chemical bonds by the maximum entropy methods and first-principles calculations. This study not only extends the scope of NTE in PbTiO<sub>3</sub>-based ferroelectrics but also expands the mixed-anion chemistry of the solid state.

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Publication Details

Journal
Materials Horizons
Published
2025-01-01
DOI
https://doi.org/10.1039/d5mh00251f
Citations
4
Primary Topic
Thermal Expansion and Ionic Conductivity
Type
article
Field-Weighted Citation Impact
2.07
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article

Anion-mediated unusual enhancement of negative thermal expansion in the oxyfluoride of PbTiO3

Runze Yu, Yue‐Wen Fang, Yuki Sakai, Youwen Long et al.
4 citations
Materials Horizons
Thermal Expansion and Ionic Conductivity
2.07
article

Anion-mediated unusual enhancement of negative thermal expansion in the oxyfluoride of PbTiO3

Runze Yu, Yue‐Wen Fang, Yuki Sakai, Youwen Long, Xubin Ye, Nianpeng Lu, Jie Zhang, Takumi Nishikubo, Mengqi Ye, Shogo Kawaguchi, Zhao Pan, Lin Wu, S. A. Nikolaev, Yoshihiro Kuroiwa, Masaki Azuma, Xiao Wang, Jun Chen, Xianran Xing, Jin Liu
article en
4 citations

Abstract

Materials featuring negative thermal expansion (NTE) properties are crucial for controlling overall thermal expansion. However, only a limited number of NTE materials are suitable as high-performance thermal expansion compensators owing to their small NTE magnitude and narrow NTE temperature range. PbTiO<sub>3</sub> is a typical perovskite-type (ABO<sub>3</sub>) ferroelectric that also exhibits a unique NTE. While an enhanced NTE compared to pristine PbTiO<sub>3</sub> can be achieved in PbTiO<sub>3</sub>-based ferroelectrics by improving their tetragonality <i>via</i> chemical substitutions at the A/B sites, the effect of anion substitution on the thermal expansion properties of PbTiO<sub>3</sub> has rarely been studied. Here, we report an oxyfluoride of PbTiO<sub>3</sub>, as an O<sup>2-</sup>/F<sup>-</sup> solid solution with fluorine concentrations up to 10%, where PbTiO<sub>3-<i>x</i></sub>F<sub><i>x</i></sub> demonstrated a reduced tetragonality as a function of fluorine. Notably, for the first time, we observed a reduced tetragonality accompanied by an unusually enhanced NTE in the present PbTiO<sub>3-<i>x</i></sub>F<sub><i>x</i></sub> of PbTiO<sub>3</sub>-based ferroelectrics, contrary to the previously reported enhanced NTE in PbTiO<sub>3</sub>-based ferroelectrics. This unconventional phenomenon can be sufficiently understood considering the chemical bonds by the maximum entropy methods and first-principles calculations. This study not only extends the scope of NTE in PbTiO<sub>3</sub>-based ferroelectrics but also expands the mixed-anion chemistry of the solid state.

Materials HorizonsVol. 12(17)
Hiroshima University (JP), Tokyo Institute of Technology (JP), Chinese Academy of Sciences (CN), Japan Synchrotron Radiation Research Institute (JP), Songshan Lake Materials Laboratory (CN), FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic (CZ), Material Physics Center (ES), Center for High Pressure Science and Technology Advanced Research (CN), Kanagawa Industrial Technology Center (JP), Institute of Physics (CN), Donostia International Physics Center (ES), University of Science and Technology Beijing (CN)
Openalex Percentile: Top 13%
Thermal Expansion and Ionic Conductivity
2.07
DOISourceOpenAlex
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