Piezoelectric ceramics are polycrystalline ceramics made by compressing and solidifying powder of a piezoelectric material, heating it to high temperatures, sintering it, and then attaching electrodes and applying a high direct current voltage to polarize it. Piezoelectric ceramics have the following advantages: they have a remarkably large electromechanical coupling coefficient, they can be mass-produced easily using ceramic technology, they can be made into elements of any shape, and they are relatively stable because most of them are oxides. However, because they are polycrystalline ceramics, they have disadvantages such as inferior oscillator characteristics to those made of single crystals such as quartz, and they change significantly over time. There are many types of piezoelectric ceramics, but the most important ones for practical applications are barium titanate (BaTiO 3 ) ceramics and lead zirconate titanate (PbTiO 3 -PbZrO 3 ) ceramics (commonly known as PZT). These ceramics are widely used as materials for piezoelectric transformers and piezoelectric vibrators. Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
圧電性をもつ物質の粉末を圧縮固化させ,これを高温加熱して焼成し磁器化したあと,電極をつけ直流高電圧を加えて分極操作を施し極性を与えた多結晶磁器を圧電セラミックスという。圧電セラミックスは電気機械結合係数の著しく大きいものが得られること,窯業技術により容易に多量生産が可能なこと,任意の形状の素子が製作できること,大部分が酸化物であるため比較的安定であることなどの長所をもつ。しかし多結晶セラミックスであるため,たとえば振動子としての特性は水晶などの単結晶を用いたものより劣る,経時変化が大きいなどの欠点をもつ。圧電セラミックスには多くの種類があるが,応用上特に重要なものはチタン酸バリウム ( BaTiO3 ) 系磁器とチタン酸ジルコン酸鉛 ( PbTiO3-PbZrO3 ) 系磁器 (通称 PZT) である。これらのセラミックスは圧電変成器や圧電振動子用材料として広く利用されている。
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