4.8.1 Piezoelectric effect u Certain materials can generate an electrical charge when subjected to mechanical strain or, conversely, can change dimensions when subjected to voltage Pierre and Jacques Curie are credited with its discovery in 1880 U The materials that exhibit a significant and useful piezoelectric effect fall into three main groups natural(quartz, Rochelle salt) and synthetic (lithium sulphate, ammonium dihydrogen phosphate)crystals polarized ferroelectric ceramics(barium titanate etc certain polymer films❑Certain materials can generate an electrical charge when subjected to mechanical strain or, conversely, can change dimensions when subjected to voltage. Pierre and Jacques Curie are credited with its discovery in 1880. ❑The materials that exhibit a significant and useful piezoelectric effect fall into three main groups: • natural (quartz, Rochelle salt) and synthetic (lithium sulphate, ammonium dihydrogen phosphate) crystals • polarized ferroelectric ceramics (barium titanate, etc.) • certain polymer films. 4.8.1 Piezoelectric effect