WSEAS Transactions on Circuits and Systems
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PZT porous ceramics with 3-3 connectivity is characterized on the large range of porosity from 25 % to more than 80%, for possible use in ultrasonic systems for medical imaging. Two methods are used to evaluate the electromechanical properties of these transducers, the resonance method and an original method based on the analysis of the time response of transducer excited by a current impulse. Porous PZT developed a same d33 than Structural PZT ceramic which gives a large voltage coefficient g33, thickness coupling coefficients kt are very large, and then planar coupling coefficients are reduced strongly, for 60% of porosity = kt/kp =3,1 the for PZT ceramic kt/kp = 0,67 These results showed that the presence of the three-dimensional porosity in ceramic causes a decoupling of the piezoelectric effects axial radial directions, to privilege the axial mode, and for large porosities the transducer vibrates exclusively according to the axial mode. The acoustic impedance (Za) is decreased by the reduction of the density of PZT. Porous PZT constitute an excellent material for use in ultrasonic systems for medical imaging.