Effect of pore size and porosity on piezoelectric and acoustic properties of Pb(Zr_0.53Ti_0.47)O₃ ceramics

Abstract

We studied the effect of porosity and pore morphology on the functional properties of Pb(Zr_0.53Ti_0.47)O₃ (PZT) ceramics for application in high frequency ultrasound transducers. By sintering a powder mixture of PZT and polymethylmetacrylate spherical particles (1.5 and 10 μm) at 1080°C, we prepared ceramics with ∼30% porosity with interconnected micrometer sized pores and with predominantly ∼8 μm spherical pores. The acoustic impedance was ∼15 MRa for both samples, which was lower than for the dense PZT. The attenuation coefficient α (at 2.25 MHz) was higher for ceramics with ∼8 μm pores (0.96 dB mm^− 1 MHz^− 1), in comparison to the ceramic with smaller pores (0.56 dB mm^− 1 MHz^− 1). The high α value enables the miniaturisation of the transducer, which is crucial for medical imaging probes. The dielectric and piezoelectric coefficients, polarisation, and strain response decreased with increased porosity and decreased pore/grain size. We suggest a possible role of pore/grain size on the switching behaviour.

Keywords:

• Porous ceramic
• Lead zirconate titanate
• Acoustic properties
• Piezoelectric properties

Acknowledgements

This work was supported by the Slovenian Research Agency (Contract Nos. P2-0105 and PR-04362). The authors would also like to thank to Jana Cilenšek, Silvo Drnovšek and Brigita Kmet. Special acknowledgement goes to Dr M. Kosec, who died in December 2012.