Huge, Millicoulomb Charge Storage in Ceramic Hydroxyapatite by Bimodal Electric Polarization

Ceramic hydroxyapatite stores up to 1.2 mC/cm2 of charge if the electret is poled at high temperature and cooled down in the presence of a field. This extraordinary storage capacity, determined by thermally stimulated depolarization measurements, was obtained at 5 kV and 873 K. The Figure illustrates some of the mechanisms, apart from H+ transport, that are involved in charge dislocation: dehydration and O2– migration at high temperature.