Preparation and Properties of Hard PZT Piezoelectric Ceramics Poled above Curie Temperature and Multilayer Actuators

Piezoelectric multilayer actuators feature large displacement generation at a relatively low driving voltage and are widely used in various fields. As the most commonly used material in multilayer actuators, soft lead zirconate titanate (PZT) ceramics have higher dielectric constant and loss, which often lead to higher power consumption and heat generation that in turn affect fatigue characteristics and stability of piezoelectric multilayer actuators. In this work, Mn-doped (in mole fraction) Pb(Sb 1/2 Nb 1/2 ) 0.02 Zr 0 .51 Ti 0.47 O 3-0.6%MnCO 3 (PSN-PZT) hard ceramic was selected as base material in order to prepare piezoelectric ceramics that have low heat generation and are suitable for the application of piezoelectric multilayer actuator. Certain amount of Li2CO3 2 CO 3 was doped as sintering aid for lowering sintering temperature of ceramics, and above-Curie-temperature polarization was utilized to enhance electric properties of ceramics. Eventually, multilayer actuator composed of this material was fabricated via tape-casting process and compared with Pb(Mg 1/3 Nb 2/3 ) 0.25 (Ti 0.48 Zr 0.52 ) 0.75 O 3 (PMN-PZT) actuator prepared with the same parameters. The results indicated that the sintering temperature of PSN-PZT ceramic was decreased to 1050 degrees C due to Li2CO3 2 CO 3 sintering aid, which introduced liquid sintering during the sintering process. PSN-PZT ceramics poled above the Curie temperature obtained optimal electric performance with 0.1% (in mass) Li2CO3 2 CO 3 doping, and the piezoelectric coefficient (d33) d 33 ) and unipolar strain at 2 kV/mm reached 388 pC/N and 0.13%, respectively. The results of temperature rise and strain degradation of both multilayer actuators indicated that the temperature rise of hard PSN-PZT actuator was about 20 degrees C lower than that of PMN-PZT actuator under 200 Hz and the strain decreased by 6% after 5x106 6 cycles. It indicates that PSN-PZT ceramics with Li2CO3 2 CO 3 doping for lowering sintering temperature have some advantages in heat generation and fatigue characteristic while having descent piezoelectric properties, which endows it an important potential application in high-power, high-frequency and other demanding working conditions.