Electrostriction of isotropic dielectrics

LL8 Section 12

An Introduction to Aqueous Electrolyte Solutions By Margaret Robson Wright, 2007

“Electrostriction in Aqueous Solutions of Electrolytes”J. E. Desnoyers, R. E. Verrall and B. E. Conway, J. Chem. Phys. 43,

243 (1965).

• A theory of electrostriction of solvent water near ions is developed. The treatment is based on a calculation of the effective pressure which would, in the absence of the field, cause the same change in volume as the field. The change in solvent volume near ions can be related, using an appropriate molecular model, to the apparent change in the volume of the salt upon dissolution. It is shown that the electrostriction arises at small ions mainly on account of changes of effective volume of the solvent rather than from compression of the ion cavity in the dielectric.

Wiki

• Certain engineered ceramics, known as relaxor ferroelectrics, have extraordinarily high electrostrictive constants. The most commonly used are– lead magnesium niobate (PMN)– lead magnesium niobate-lead titanate (PMN-PT)– lead lanthanum zirconate titanate (PLZT)

• Electrostriction can produce a strain of 0.1% at a field strength of 2 million volts per meter (2 MV/m) for the material called PMN-15

• Applications– Sonar projectors for submarines and surface vessels– Actuators for small displacements

When T,P are constant, it is the Gibbs potential that spontaneously seeks a minimum.