Electric field induced piezoelectric response in ferroelectric materials near the paraelectric ferroelectric transition

In many ferroelectric materials, the piezoelectricity can be induced by an applied electric field and the material will return to piezoelectric inactive state when the field is reduced to zero. Based on thermodynamic theory, the effect of temperature and applied electric field on the electromechanical response is analyzed for materials with a first order and continuous ferroelectric-paraelectric phase transitions. It is concluded that near the critical point of a first transition, a giant piezoelectric constant and a high electromechanical coupling factor can be achieved. Experimental results on a series of (BaSr)TiO ₃ samples show that an exceptionally high induced piezoelectric constant can be obtained for the material with a first order transition