|About this Abstract
||Materials Science & Technology 2020
||Ceramics and Glasses Simulations and Machine Learning
||Theoretical Calculation of Formation Energies and Site Preference of Substitutional Divalent Cations in Carbonated Apatite
||Tatasushi Saito, Tatsuya Yokoi, Atsutomo Nakamura, Katsuyuki Matsunaga
|On-Site Speaker (Planned)
Carbonated apatite (CAp) is hydroxyapatite (HAp) containing carbonate ions (CO32-) and is used in bone grafts. It was reported that substitutional CO32- increases solubility of foreign cation impurities into CAp, which affects bone tissue formation ability. However, underlying mechanisms are still unclear. In this study, first principles calculations were performed to investigate defect formation energies (ΔEf) and site preference of substitutional divalent cations (M2+) in CAp. For all M2+ studied, it was found that ΔEf for the most stable substitutional sites are lower in CAp than in HAp. This indicates that M2+ are preferentially substituted into CAp over HAp. Detailed analyses of atomic environments indicated that the presence of CO32- vary the bond lengths and coordination number of Ca sites. As a result, M2+ is favorably substituted for particular Ca sites at which mismatches in the ionic-size and coordination number are minimized between Ca2+ and M2+, decreasing ΔEf.