Manufacture and characterization of porous ferroelectrics for piezoelectric energy harvesting applications

Porous ferroelectric materials have been evaluated for their piezoelectric energy harvesting capabilities. Macro-porous barium titanate (BaTiO₃) ceramics were fabricated with a range of porosities using the burned out polymer spheres process. The pore fraction was tailored by mixing a pore forming agent with BaTiO₃ powder in varying amounts by weight before cold-pressing and pressureless sintering. Introducing porosity into the ferroelectric significantly increased the energy harvesting figure of merit, with a maximum of 2.85pm²/N obtained at ∼40% relative density compared with ∼1.0 pm²/N for the dense material. The results demonstrate that introducing porosity into a piezoelectric potentially provides an effective route to improving the vibration energy harvesting capability of these materials.