Density functional study of structural, electronic and vibrational properties of Mg- and Zn-doped tricalcium phosphate biomaterials

Zn- and to a lesser extent Mg-releasing tricalcium phosphate (Zn- and Mg-TCP) have excellent bioactivities which do not exist in their parent TCP base. However, the mechanisms through which the dopants affect the properties are not known. In order to gain insight from geometrical and electronic structures and chemical bonding, ab initio density functional calculations have been performed for these materials using cluster models. The results show a distorted structure for Zn-TCP which may be related to its bioactivity, whereas no such distortion was found for TCP and Mg-TCP. The infrared spectra of these materials has been calculated, and the relationship to the structure investigated.