5. Porosity Graded Piezoelectric Ceramics (PGPC)
The ultrasonic properties of the piezoelectric materials could be improved producing a
transducer (the active layer) with a functionally-graded structure (Fig. 3). The porositygraded
structure could match a dense active layer with high piezoelectric constant able to
efficiently transmit/receive the acoustic/electrical signal with a porous layer with a lower
piezoelectric response but with an acoustic impedance appropriate for the porous matching
layer and the investigated media.