SURFACE PROPERTIES OF CERAMIC HYDROXYAPATITE ELECTRETS

: Hydroxyapatite (HAp) is the principal inorganic ingredient of human teeth and bone, and well-known as an excellent biocompatible material. HAp has been found to be polarized with an external electric field at a high temperature. Electrets are defined as the solids with functions that quasi-permanent surface charges. However, fundamental characteristics of electric fields due to HAp electrets have never been reported. Hence, this purpose is investigation of the properties of the surface electric fields of HAp bioceramic electrets; the surface potentials due to overlapping plural electrets with different electric potentials and signs; and a screening effect on electric fields with electrets due to a conductor and a dielectric. Polarized charges of the HAp electret have generated an electric field around the electret. The principle of superposition has held for the surface potentials of plural electrets. The screening effect by a conductor or a dielectric has been observed.