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Electrostriction (cf. magnetostriction) is a property of all electrical non-conductors, or dielectrics, that causes them to change their shape under the application of an electric field. == Explanation == Electrostriction is a property of all dielectric materials, and is caused by a slight displacement of ions in the crystal lattice upon being exposed to an external electric field. Positive ions will be displaced in the direction of the field, while negative ions will be displaced in the opposite direction. This displacement will accumulate throughout the bulk material and result in an overall strain (elongation) in the direction of the field. The thickness will be reduced in the orthogonal directions characterized by Poisson's ratio. All insulating materials consisting of more than one type of atoms will be ionic to some extent due to the difference of electronegativity of the atoms, and therefore exhibit electrostriction. The resulting strain (ratio of deformation to the original dimension) is proportional to the square of the polarization. Reversal of the electric field does not reverse the direction of the deformation. More formally, the electrostriction coefficient is a fourth rank tensor (), relating second order strain () and first order polarization tensors (, ). The related piezoelectric effect occurs only in a particular class of dielectrics. Electrostriction applies to all crystal symmetries, while the piezoelectric effect only applies to the 20 piezoelectric point groups. Electrostriction is a quadratic effect, unlike piezoelectricity, which is a linear effect. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「electrostriction」の詳細全文を読む スポンサード リンク
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