Preparation of porous PZT with high connectivity using capsule-free O2-HIP and their dielectric properties

Abstract

The processing of porous PZT ceramics with high connectivity was investigated using capsule-free O₂-HIP technology. PreHIPed porous PZT bodies were prepared by pressureless-sintering of green compacts with various amounts of spherical PMMA particles, followed by hot-isostatically pressed at 1100°C and 200 MPa for 1 h in 5% O₂/Ar mixture gas atmosphere. Little densification of porous PZT sintered bodies occurred by capsule-free O₂-HIP treatment, resulting in the formation of well-developed neck growth between PZT grains.

They exhibited a homogeneous microstructure with a bimodal pore distribution consisting of both several μm and 50 ∼ 80 μm pore sizes.

The HIPed porous PZT ceramics have a larger permittivity and a smaller depolarizing factor about a half rather than those of pressureless-sintered porous PZT bodies, suggesting that the HIPed PZT has a higher connectivity. Piezoelectric g₃₃ constant-porosity relations were also described.

Key Words:

• Capsule-free HIP
• connectivity
• depolarizing factor
• ceramic dielectric permittivity
• ceramic composites