Charge storage observation in corona-charged oxy-hydroxyapatite ceramics

Oxy-hydroxyapatite (OHA), which is a OH-deficient hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂O_x/2) showing ionic (H⁺, O^2-, and OH^-) conductivity, can be converted to an OHA electret with a stable surface potential of more than several kilovolts by applying a DC electric field under heating (thermal electret method). This report presents a potential corona irradiation method for producing OHA electrets. The OHA ceramic was heated to a predetermined temperature, and corona irradiation was performed in a state in which carrier diffusion was activated inside the OHA ceramic. The state of the stored charges in OHA ceramics was verified by thermally stimulated depolarization current analysis.