Question

What is the structural origin of the pyroelectric property?

Answer 1

The structural cause of the pyroelectric effect is the low symmetry of the crystals of the pyroelectric substance.

In the first place the unit cell of pyroelectric crystals has no center of symmetry, and secondly it is polar. For this reason, the macrocrystal tends to be spontaneously polarized by changes in temperature and by mechanical action too.