Piezoelectric devices — direct/converse piezoelectric effect, constitutive equations (d, e, g, h coefficients), PZT material properties, bending (bimorph/unimorph) vs. stack actuators, resonance frequency, electromechanical coupling factor k, energy harvesting (Roundy model), ultrasonic transducers, hydrophones (d_h, g_h), and applications in sensors, actuators, vibration control, MEMS.
