Piezoelectric Properties of PZT‐Based Ceramic with Highly Aligned Pores

Porous lead zirconate titanate–lead zinc niobate (PZT–PZN) piezoelectric ceramics with a high degree of pore alignment were fabricated using directional freeze casting of a ceramic/camphene slurry. Well-aligned pores were formed as the replica of the camphene dendrites that grew in a preferential orientation, while a high porosity of 90% was achieved by employing a low initial solid loading of 5 vol%. As the orientation angle of the pores to the poling direction was decreased, the hydrostatic piezoelectric properties, such as hydrostatic piezoelectric strain coefficient (dh), the hydrostatic piezoelectric voltage coefficient (gh), and the hydrostatic figure of merit, increased significantly. The sample containing pores aligned parallel to the poling direction showed an extremely high HFOM of 161019 × 10−15 Pa−1, which was ∼1300 times higher than that (124 × 10−15 Pa−1) of the dense sample, owing to the presence of aligned pores.