Abstract
The dipole formation and relaxation characteristics of hydroxyapatite (HA) ceramics were evaluated from the aspect of the effects of poling conditions and the microstructures of raw ceramics. Optimizing the measured TSDC curves by the theoretical ones, the shift of the peak shapes, position and the value of Q were found to be originated in the existence of four possible polarized states which relaxed with the different activation energy and the pre-exponential factor of relaxation time. The four states were basically mixed in each electret but the contribution ratio of each state to the total dipoles was varied by the preparative conditions of the electrets.It means the charge storage Q and the dipole relaxation time can be individually controlled by the optimal selection of the sintering and poling conditions.
