ABSTRACT
The ageing and field-forced deageing characteristics of a commercial cobalt-doped BaTiO3 piezoceramic are reported. It was found that the internal bias field in unpoled specimens reduced according to an exponential time law during field-forced deageing. The time constants associated with the deageing process were 159, 33 and 25 s at 30, 60 and 90 °C respectively, indicating an activation energy of 0.36 eV. In contrast, field-forced deageing of poled specimens yielded a logarithmic behaviour. Furthermore, the internal bias field in poled specimens proved to be extremely resistant to the deageing procedure, with the result that a significant internal bias field (Ei ≈ 0.1 kV mm-1) remained after the application of a continuous AC field of 2 kV mm-1 for 12 000 s at 30 and 60 °C.
