DIW-3D printed PZN-PLZT piezoelectric ceramics: Solid-loading-dependent sintering behaviors and electrical properties

Direct ink writing (DIW) offers a promising route for fabricating piezoelectric ceramics with complex architectures, yet the solid loading of ceramic inks plays a decisive role in balancing printability, densification, defect formation, and final electrical performance. In this work, 0.25Pb(Zn 1/3 Nb 2/3 )O 3 -0.75Pb 0.96 La 0.04 (Zr 0.53 Ti 0.47 )O 3 ceramics with 0.5 wt% Sb 2 O 5 addition were fabricated by DIW using inks with solid loadings of 74–79 wt%. The influence of solid loading on rheological behavior, debinding/sintering characteristics, microstructural evolution, and electrical properties was systematically investigated. All inks exhibited pronounced shear-thinning behavior, while increasing solid loading strengthened the particle network and improved shape retention. A TG/DTG-guided multistep debinding schedule was employed to suppress gas accumulation, cracking, and residual porosity during binder removal. With increasing solid loading from 74 to 77 wt%, enhanced particle packing, improved interlayer bonding, and promoted densification led to increased dielectric, ferroelectric, and piezoelectric responses. However, further increasing the solid loading to 78–79 wt% deteriorated ink flowability and induced agglomeration and interlayer defects, thereby hindering polarization switching and degrading electrical performance. The ceramic printed with 77 wt% solid loading exhibited the best overall properties, including a room-temperature relative permittivity of approximately 2.95 × 10 3 at 1 kHz, a piezoelectric coefficient d 33 of 491 pC/N, and a Curie temperature of approximately 212 °C. These results reveal the solid-loading-dependent rheology–defect–polarization relationship in DIW-printed PZN-PLZT-Sb ceramics and provide guidance for optimizing additively manufactured piezoelectric ceramic components.