How can the electric polarization be induced the strain gradient?

[Silicon]

How can the electric polarization be induced by the strain gradient?

It is said in some papers the strain gradient can induce electric polarization in solid materials.
Why can it happen?
Who can explain this phenomenon to me?

 

[inha]

Do you mean piezoelectric crystals? I'm asking because those wouldn't need the strain to be nonuniform.

 

[Silicon]

Do you mean piezoelectric crystals? I'm asking because those wouldn't need the strain to be nonuniform.

Not only piezoelectric crystals, but also some other non-piezoelectric materials have this effect. Why can it happen?

 

[ZapperZ]

In the most naive sense, a strain on any crystal will cause a charge redistribution within the crystal. Depending on how such a redistribution occurs, if it happens to be in the "right" orientation, when you will have a net polarization of + and - charges in a particular direction. When this occurs, then an EM wave in the right range of frequency passing through the material will be polarized along that same direction.

Zz.