Investigation on electric properties of 0.57(Bi0.8La0.2)FeO3-0.43PbTiO3 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.