Engineering Physics

6.7 Piezoelectricity

The word ‘Piezo’ means ‘pressure’ in Greek. So, ‘piezoelectricity’ means ‘pressure electricity’. Piezoelectric phenomenon was discovered by Curie brothers in 1880. Piezoelectric effect is shown by certain non-centrosymmetric crystals, such as quartz, rochelle salt, tourmaline and barium titanate. Electric polarization develops opposite charges on their surfaces by stress. On these substances, a mechanical stress produces an electric polarization and reciprocally, an applied electric field produces a mechanical strain. These effects are called the direct and inverse piezoelectric effects. Crystals with centres of inversion do not exhibit piezoelectricity.

A crystal can exhibit piezoelectricity only if its unit cell lacks centre ...