Utilization of ionic conduction for developing ceramic electrets applicable to vibration power generator

驻极体发电机可以将低频振动（1-100赫兹）直接转化为电能，但由于其低致电能力，其应用受到限制。尽管较高的驻极体表面电位对提高功率密度是有效的，但目前使用的聚合物驻极体由于其对硬充电处理的电阻率较差，其电位水平几乎饱和。因此，我们的目标是基于控制离子迁移及其在陶瓷中的凝聚的方法来开发新的陶瓷驻极体。通过本研究，我们发现氧羟基磷灰石（OHA）在高温直流电场下可以发生极化。极化OHA陶瓷的表面电位达到1000 V以上，且稳定至少一年以上。考虑到聚合物驻极体的表面电势限制在几百伏，OHA驻极体应该是应用于驻极体发电机的有前途的材料。

An electret power generator can convert low-frequency vibrations (1-100 Hz) directly into electricity, however, the applications are limited because of it's low electrogenic ability. Although the higher surface potential on the electrets is effective to promote the power density, the potential level of currently-used polymer electrets is almost saturated due to their poor resistivity against the hard charging treatment.Hence we aimed to develop new ceramic electrets based on the approach of controlling ionic migrations and their congelation within the ceramics. Through this study, we found that oxyhydroxyaptite (OHA) could be polarized under a dc electrical field at elevated temperature. The surface potential on polarized OHA ceramics reached above 1000 V, which was stable at least over a year. Considering the fact that the surface potential of polymer electrets is limited to several hundred volts, OHA electrets should be promising material applicable to the electret power generator.