Question

How would you say that all ferroelectric solids are piezoelectric,but all piezoelectric solids are not ferroelectric solids?? Explain to satisfy this statement.

Answer 1

Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field.
Piezoelectrics are materials that can create electricity when subjected to a mechanical stress and vice versa.

All ferroelectrics are piezoelectric because of lack of symmetry i.e. piezoelectric effect is shown by materials having non centrosymmetry(material which cannot be inversed along an axis). Ferroelectrics are non centrosymmetric materials and hence they are piezoelectrics.

But, all piezoelectrics are not ferroelectrics because ferroelectrics are spontaneously polarised, but piezoelectric polarise only at an optimum condition