Electron beam interaction, damage and reconstruction of hydroxyapatite

Synthetic hydroxyapatite (HAP) samples were observed in the high resolution transmission electron microscope (HRTEM) using an electron beam of 400 kV and, after formation of “voids”, the reconstruction of its structure was recorded. This phenomenon is most possible due to various electron–crystal interaction mechanisms, such as ballistic knock-on damage, electron-beam heating, etc., but it is still not quite sure which of them creates these contradictory phenomena. This is the first time that a process of destruction/reconstruction in apatite crystals under electron irradiation is reported.