Ferroelectric crystals

…When the temperature of a crystal is changed, the crystal is deformed by thermal expansion, and the distance between the center of gravity of the positive charge and the center of gravity of the negative charge changes, so the magnitude of the spontaneous polarization changes, which is observed as a change in the surface charge. A crystal whose spontaneous polarization direction is reversed by an externally applied electric field is called a ferroelectric crystal, and a state in which the spontaneous polarization within the crystal is aligned in one direction is called a single domain state. Some single-domain ferroelectric crystals exhibit large pyroelectricity. …

*Some of the terminology that refers to "ferroelectric crystal" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…結晶の温度を変えると，熱膨張により結晶が変形し，正電荷の重心と負電荷の重心との間隔が変わるため，自発分極の大きさが変わり，これが表面電荷の変化として観察される。　自発分極の向きが，外から加えられた電場により反転する結晶を強誘電体結晶と呼び，結晶内の自発分極が一方向にそろった状態を単一分域の状態という。この単一分域の強誘電体結晶の中には大きな焦電気を示すものがある。…

※「強誘電体結晶」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報