Sintering Behavior, Properties, and Applications of Co‐Fired Piezoelectric/Low Temperature Co‐Fired Ceramic ( PZT ‐ SKN / LTCC ) Multilayer Ceramics

Materials and processing conditions have been developed allowing co‐firing of fluxed PZT ‐ SKN materials with commercial low temperature co‐fired ceramic ( LTCC ) tapes. Previously, Pb ( Zr _0.53 , Ti _0.47 ) O ₃ – Sr (K _0.25 , Nb _0.75 ) O ₃ ( PZT ‐ SKN ) ceramics fluxed with 1 wt% LiBiO ₂ and 1 wt% CuO addition were shown to sinter to high density at 900°C for 1 h, with a large d ₃₃ piezoelectric coefficient of ~415 pm/V. Currently, the master sintering curve ( MSC ) approach has been used to study the densification behaviors of fluxed PZT ‐ SKN and LTCC tapes. Different sintering mechanisms for fluxed PZT ‐ SKN ceramics and LTCC materials are confirmed by analyzing the apparent activation energy ( Q _a ). Using knowledge gained from MSC results, an optimized sintering profile was developed. Multilayer PZT ‐ SKN / HL 2000 (HeraLock ^™ Tape, Heraeus) stacks co‐fired at 900°C for 0.5 h maintain large piezoelectric coefficient (high field d ₃₃ > 340 pm/V). EDS analysis reveal limited interdiffusion of Pb from PZT ‐ SKN layers in LTCC and the appearance of Al , Ca , and Si in the PZT ‐ SKN near the PZT ‐ SKN / LTCC interface. Further, elemental interdiffusion was not detected at the center of piezoelectric layer in PZT ‐ SKN / LTCC multilayer ceramics and no subsequent reduction in piezoelectric coefficient d ₃₃ was observed. Finally, a piezoelectric microbalance with mass sensitivity of 150 kHz/mg was fabricated using the materials and methods developed.