Effect of two-step sintering on micro-honeycomb BaTiO3 ceramics prepared by freeze-casting process

Micro-honeycomb barium titanate (BaTiO3) ceramics, which have uniformly distributed one-dimensional pore channels, were prepared by freeze-casting suspensions of hydrothermally synthesized BaTiO3 nanopowder with a particle size of 100 nm. The effects of sintering schedules such as sintering temperature and holding time on pore size distribution, porosity, pore wall density and grain size were studied. The grain size on the pore wall of BaTiO3 is around 1–2 μm after two-step sintering. The crystallographic structure of all samples was tetragonal phase regardless of the sintering schedules. Ferroelectric domains were shaped in a stripe and the domain width obviously increased after polarization. The micro-honeycomb BaTiO3 sintered at lower temperature or shorter holding time showed larger piezoelectric coefficient d33 and smaller dielectric constant εr.