Investigation on electric properties of 0.57(Bi 0.8 La 0.2 )FeO 3 ‐0.43PbTiO 3 porous ceramics prepared by burnable plastic sphere method

In this study, 0.57(Bi 0.8 La 0.2 )FeO 3 ‐0.43PbTiO 3 (BLF‐PT) porous ceramics were fabricated by the burnable plastic sphere method using polymethyl methacrylate (PMMA) as a pore forming agent. X‐ray diffraction results reveal that BLF‐PT porous ceramics mixed with tetragonal and rhombohedral phases display the single perovskite structure, changing little for different porosities. Scanning electron microscope images show that porosity of BLF‐PT ceramics increases with the increase of PMMA content with average grain size of 3.2–3.5 μm. Different from the continuous decrease of dielectric constant ε r and remnant polarization P r , piezoelectric constant d 33 of BLF‐PT porous ceramics increases initially but then drops with the increase of porosity that reaches to the maximum of 230 pC/N at porosity of 8.5 vol.%. The abnormal enhancement of piezoelectric property is attributed to the unique three‐dimensional grid porous ceramic skeleton and uniformly distributed grain size. Moreover, acoustic impedance Z of BLF‐PT porous ceramic is 11.2 MRayls at porosity of 24.3 vol.% comparing with that of 17.7 MRayls for bulk ceramics, which reduces by 58%. BLF‐PT porous ceramics at lower porosity with enhanced piezoelectric and acoustic matching performances have a great potential in the fields of underwater acoustic transducers and medical ultrasonic diagnosis.