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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(Zr0.53, Ti0.47)O3Sr(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.