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

Abstract

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(Zr0.53, Ti0.47)O3–Sr(K0.25, Nb0.75)O3 (PZT‐SKN) ceramics fluxed with 1 wt% LiBiO2 and 1 wt% CuO addition were shown to sinter to high density at 900°C for 1 h, with a large d33 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 (Qa). Using knowledge gained from MSC results, an optimized sintering profile was developed. Multilayer PZT‐SKN/HL2000 (HeraLock™ Tape, Heraeus) stacks co‐fired at 900°C for 0.5 h maintain large piezoelectric coefficient (high field d33 > 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 d33 was observed. Finally, a piezoelectric microbalance with mass sensitivity of 150 kHz/mg was fabricated using the materials and methods developed.