Porous PZT Ceramics with High Hydrostatic Figure of Merit and Low Acoustic Impedance by TBA‐Based Gel‐Casting Process

Porous lead zirconate titanate (PZT) ceramics with three-dimensionally interconnected pores were prepared using a novel tert-butyl alcohol-based gel-casting process, an unconventional technique in acquiring high-porosity ceramics. In the present work, PZT ceramics with porosity ranging from 31.3% to 58.6% were fabricated by adjusting the initial solid loading and sintering temperature. The fabricated samples were characterized in terms of both porous structure and functional properties to clarify the underlying correlation. With the increase of porosity, relative permittivity (er) decreased to a significantly low value compared with dense PZT ceramics while the longitude piezoelectric coefficient (d33) exhibited a moderate decline, which could be attributed to the unique structure with homogeneous pore distribution. As a result, the resultant samples possessed a high value of hydrostatic figure of merit, 4100 times higher than that of dense materials. The acoustic impedance (Z) showed a linear dependence on porosity with the lowest magnitude reaching 3.0 MRayls (10 6 kg . (m 2 . s) –1 ), hopefully leading to enhanced coupling with biological tissue or water.

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