Aging of the ceramic occurs very rapidly in the first few hours. After a few days the changes in the material properties are very small and decrease logarithmically. The aging process can be attributed to the relaxation of the dipoles in the material. Piezoelectric ceramic materials possess electrical, mechanical and electromechanical properties resulting from the chemical formulation and the manufacturing processing. High dielectric constants are desirable for they result in low impedances.
Low dissipations are desirable for they result in low-electrical losses.
Typical electromechanical coupling results in a more efficient transfer of electrical energy to mechanical energy. Many of these properties are dependent upon the axis of measurement. The axis being defined relative to the poled axis. Depolarization of the piezoelectric ceramic can result if it is exposed to excessive heat, electrical drive or mechanical stress or any combination thereof. A change in ceramic temperature will result in a change in mechanical dimensions.