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A Fabrication and Measurement Method for a Flexible Ferroelectric Element Based on Van Der Waals Heteroepitaxy
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Ferroelectricidad inadecuada híbrida en (Sr, Ca) 3Sn2O7 y más allá: Relación universal entre la temperatura de
Suguru Yoshida1, Hirofumi Akamatsu, Ryosuke Tsuji1
1Department of Material Chemistry, Graduate School of Engineering , Kyoto University , Katsura Nishikyo-ku , Kyoto 615-8510 , Japan.
Journal of the American Chemical Society
|October 24, 2018
Resumen
La ferroelectricidad híbrida inadecuada utiliza distorsiones geométricas para crear polarización. Los investigadores encontraron una relación lineal entre la temperatura de Curie (TC) y el factor de tolerancia de Goldschmidt (t) para los nuevos materiales ferroeléctricos.
Área de la Ciencia:
- Ciencias de los materiales
- Física del estado sólido
- La cristalografía
Sus antecedentes:
- La ferroelectricidad híbrida impropia aprovecha las distorsiones geométricas para la polarización, ofreciendo una ruta a nuevos materiales ferroeléctricos y multiferroicos.
- Los métodos de diseño actuales que utilizan la teoría de grupos y los primeros principios predicen con precisión las simetrías de los cristales, pero luchan con parámetros clave como la temperatura de Curie (T C ).
Objetivo del estudio:
- Establecer una relación predictiva y cuantitativa entre TC y el factor de tolerancia de Goldschmidt (t) en ferroeléctricos híbridos inadecuados.
- Investigar el efecto puramente geométrico (tamaño iónico) en las transiciones ferroeléctricas en los sistemas Ruddlesden-Popper (RP).
Principales métodos:
- Utilizó n = 2 sistemas Ruddlesden-Popper (RP) A3 B2 O7, específicamente (Sr1-x Cax) 3 Sn2 O7, para estudiar los efectos geométricos.
- Centrado en materiales que carecen de mecanismos de distorsión ferroeléctrica electrónica (por ejemplo, cationes d0 y 6s2).
- Determinado experimentalmente TC para varias composiciones y correlacionado con el factor de tolerancia (t).
Principales resultados:
- Se observó una transición ferroeléctrica a paraeléctrica con TC = 410 K para Sr3Sn2 O7.
- Se encontró que TC aumenta linealmente hasta 800 K con el aumento del contenido de Ca2+ (disminuyendo t).
- Se demostró que esta relación lineal TC-t se aplica a todos los conocidos A3 B2 O7 híbridos de ferroeléctricos impropios.
Conclusiones:
- Se estableció una correlación predictiva entre TC y el descriptor químico del cristal, el factor de tolerancia de Goldschmidt (t), basado en el desajuste del tamaño iónico.
- Este hallazgo proporciona una guía para estimar TC en ferroeléctricos híbridos inadecuados.
- Complementa los enfoques de diseño existentes basados en la teoría de grupos y los primeros principios para el descubrimiento de nuevos materiales ferroeléctricos.
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