Lead-free barium titanate ceramics with large piezoelectric constant fabricated by microwave sintering

A lead-free barium titanate (BaTiO3) ceramics with a high density and a large piezoelectric constant, d33, as manufactured at 1320°C by microwave sintering, using a pure fine powder with a particle size of 100 nm produced by hydrothermal synthesis. The density of the ceramic with a 3.4 µm grain size was more than 98.3% of the theoretical value. The ceramic after poling had a dielectric constant of e33T/e0 =4200, an electromechanical coupling factor planar mode of kp =36% and d33 =350 pC/N. The value of d33 is the largest one ever reported for lead-free BaTiO3 ceramics.