Piezoceramics?

Question

Could someone please explain to me why piezoceramics vibrate when a current is passed through them?

Also, are they cheap? Are they environmentally friendly?

Answer 1

The crystals are arranged in a symmetric pattern, and the electrons on the atoms are balanced, sometimes with a polarity, that is, a balanced arrangement of + and - charges in the whole crystal.  Piezos are easily disturbed by force or electricity.  These cause the electrons in the crystal lattice to shift.  If a force is applied the shift geneerates voltage and electricity.  If a current is applied, the electrons shift back and forth, and the frequency of vibration depends on the voltage or current passing through.  It's like applying a force to a spring.  The spring vibrates back and forth seeking equilibrium.

Some are cheap, some are costly.  Some are non hazardous, some are not.  There are lots of different piezo materials.