Fabrication and electrical properties of porous BS–0.64PT high temperature piezoceramics using polystyrene microsphere

Porous BiScO3–0.64PbTiO3 (BS–0.64PT) ceramics were fabricated by using burnable plastic sphere technique (BURPS). Self-synthesized polystyrene microsphere (PS, φ360 nm) was used as pore forming agent (PFA). Porosity of the porous ceramics was regulated by adjusting sintering temperature and volume fraction of PFA. The porous ceramics were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). All samples were pure tetragonal perovskite. Properties of the porous ceramics, including porosity, piezoelectric coefficient (d33) and dielectric properties (Ɛr) were measured. Electromechanical coupling coefficients (kp, kt, k31), mechanical quality factor (Qm), piezoelectric coefficient (d31, dh), hydrostatic voltage coefficient (gh), acoustic impedance (Z), hydrostatic figure of merit (HFOM) were derived from impedance spectrum. Sintering temperature and volume fraction of PFA were optimized to bring out porous ceramics with highest gh and HFOM. Porous ceramic with 50 vol% PS microspheres sintered at 1000 °C possessed porosity of 17.12%, with gh and HFOM to be 0.024 V/m Pa and 6087×10−15/Pa, respectively.