Everything about Electrostriction totally explained
Electrostriction is a property of all electrical non-conductors, or
dielectrics, that causes them to change their shape under the application of an
electric field. (Compare with
magnetostriction.)
Explanation
Electrostriction is a property of all dielectric materials, and is caused by the presence of randomly-aligned electrical domains within the material. When an electric field is applied to the dielectric, the opposite sides of the domains become differently charged and attract each other, reducing material thickness in the direction of the applied field (and increasing thickness in the orthogonal directions due to
Poisson's ratio). The resulting
strain (ratio of deformation to the original dimension) is proportional to the square of the
polarization. Reversal of the electric field doesn't reverse the direction of the deformation.
More formally, the electrostriction coefficient is a fourth order tensor (
It should be noted that the related
piezoelectric effect occurs only in a particular class of dielectrics. Electrostriction is a
quadratic effect, unlike piezoelecticity, which is a
linear effect. In addition, unlike piezoelectricity, electrostriction can't be reversed: deformation won't induce an electric field.
Materials
Although all dielectrics exhibit some electrostriction, certain engineered ceramics, known as
relaxor ferroelectrics, have extraordinarily high electrostrictive constants. The most commonly used are:
Magnitude of effect
Electrostriction can produce a strain of 0.1 % at a fieldstrength of 2e6 Volt/meter for the material called PMN-15 (TRS website listed in the references below). The effect appears to be quadratic at low fieldstrengths (up to 3e5 V/m) and roughly linear after that, up to a maximum fieldstrength of 4e6 V/m . Therefore, devices made of such materials are normally operated around a bias voltage in order to behave nearly linearly; This will probably cause deformations to lead to a change of electric charge, but this is unconfirmed.
Applications
Sonar projecors for submarines and surface vessels
Actuators for small displacementsFurther Information
Get more info on 'Electrostriction'.
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