Structure and properties of CO 2 – centers in biological and synthetic hydroxyapatite

Abstract

Biological and synthetic carbonate-containing hydroxyapatites (HAP) were exposed to γ- rays and studied by the electron paramagnetic resonance (EPR) and the electron-nuclear double resonance (ENDOR). Two types of CO2− radicals - axial and orthorhombic ones - were shown to be the dominating γ-induced paramagnetic centers in the abovementioned materials. The study of metastable radiation-induced centers allowed to identify these defects with molecular ions CO33− in B position. The mechanism of CO2− radical formation was proposed to be CO32−→ CO33−→ CO2−.