5. Conclusion

In terms of electrical and mechanical properties, piezoelectric ceramics offer a number of advantages:

• These inorganic materials are brittle at service temperatures, with high Young's moduli of the order of 60 to 70 GPa, and can tolerate only slight deformations (200 to 800 ppm);

• depending on the deformation mode, the electromechanical coupling coefficient can vary between 0.25 and 0.75 ;

• the operating temperature may be higher than ambient temperature, but for ferroelectric materials it must be below the Curie temperature, which for PZTs is between 250 and 350°C, depending on the chemical composition (to avoid partial depolarization and accelerated aging, operating temperatures are generally limited to 100°C below the Curie temperature);

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