Characterization of Porous Thick Film PZT Composite for Bilayer Ultrasonic Transducers

Evaluation of the piezoelectric behaviour produced by a thick-film transducer using digital speckle pattern interferometry

“…(4) resulted ðd 33 Þ eff ¼ 270 Â 10 À12 N=C. This result compares quite well with the value ðd 33 Þ eff ¼ 297 Â 10 À12 N=C which was determined in other thick-film transducers produced using the same piezoelectric material and similar manufacturing conditions, through the measurement of the permittivity and other electromechanical parameters [5]. It is noted that due to the previously mentioned reasons, the thick-film transducer is less active piezoelectrically than the bulk ceramic material, as from the PZ27 data sheet d 33 ¼ 425 Â 10 À12 N=C [4].…”

“…The active element of the paste was a PZT powder manufactured by Ferroperm (PZ27) [4], which was dispersed in a commercial vehicle to obtain rheological properties suitable for the screen-printing process [5]. The connection between the PZT particles was improved by adding a lead borosilicate glass that also helped to attach the film to the substrate due to the relatively low sintering temperature that was used in the manufacture process.…”

Evaluation of the effect of porosity and substrate on the piezoelectric behaviour of thick-film PZT elements

“…The piezoelectric thick film was obtained by screen printing a paste on an alumina substrate and then by drying and sintering the film with a temperature-time profile determined by the paste characteristics. The active element of the paste is a PZT powder manufactured by Ferroperm (PZ27) which was dispersed in a commercial vehicle (ESL 400/403 of the Electro Science Laboratories) to obtain rheological properties suitable for the screen printing process [10,15]. The connection between PZT particles is improved by adding a lead borosilicate frit glass that also helps to attach the film to the substrate due to the relatively low temperature sinter that has been used in this process.…”

“…Before using the piezoelectric paste, a lower Ag/Pt electrode is printed on the alumina substrate, and after the PZT film is sintered, an upper electrode of the same material is printed on the PZT. Each layer is dried at 140 • C for 10 min and it is then sintered at 850 • C [15]. Finally, the ceramic film is polarized by heating the sample at 110 ± 5 • C and an electric field of 3 MV m −1 is applied between the electrodes for 30 min.…”

Ultrasonic array of thick film transducers for biological tissue characterization

“…T The structure that is obtained using this process has a high degree of internal porosity and its density is approximately 20% lower than for the same type of PZT in traditional bulk ceramic [5]. The method produces a porous structure because from the beginning the PZT particles are not compressed in the vehicle.…”