Ab initio simulation of Si-doped hydroxyapatite
Ab initio simulation of Si-doped hydroxyapatite
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DOI：
10.1021/cm051989x
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发表时间：
2006-01-24
影响因子：
8.6
通讯作者：
Stott, MJ
中科院分区：
文献类型：
--
作者：
Astala, R;Calderín, L;Stott, MJ
掺硅羟基磷灰石是一种可用作骨修复材料的生物陶瓷，它保留了高达2wt%Si的羟基磷灰石的六方结构。提出了不同的SiO44离子取代PO43-的电荷补偿机制。此外，还报道了晶格参数随硅掺杂的变化。这可能是不同的电荷补偿机制的结果，而不同的电荷补偿机制又可能取决于材料的制备方法。用从头算总能量方法研究了掺硅羟基磷灰石的不同电荷补偿机制。研究了氢空位、氧空位和氢空位的形成机理。这些机制对应于不同程度的脱水，因此取决于水的分压和化学势。对原子位置和晶胞参数进行了充分的驰豫，得到了平衡结构、平衡晶格参数和原子排列的基态能量。结果表明，水的化学势决定了哪种电荷补偿机制是稳定的。对于较小的水化学势，涉及OH空位的机制是稳定的，但对于较大的值，导致HSiO4形成的机制是稳定的。其他被考虑的机制是不稳定的。
Si-doped hydroxyapatite is a bioceramic useful as a bone repair material retaining the hexagonal structure of hydroxyapatite up to about 2 wt % Si. Different mechanisms for charge compensation for the SiO44- ion substituting for the PO43- have been proposed. Also, variations are reported in the dependence of the lattice parameters on the Si doping. These may be a result of different charge compensation mechanisms which may in turn depend on the method of preparation of the material. Calculation using ab initio total energy methods have been performed to investigate different mechanisms for charge compensation in Si-doped hydroxyapatite. Mechanisms involving an OH vacancy, an oxygen vacancy, and an additional hydrogen are studied. These mechanisms correspond to different degrees of dehydration and, consequently, depend on water partial pressure and chemical potential. Full relaxation of the atomic positions and the unit cell parameters was performed, and ground-state energies of the equilibrium structures, equilibrium lattice parameters, and atomic arrangements were obtained. The results indicate that which charge compensation mechanism is stable depends on the chemical potential of water. For small values of the water chemical potential the mechanism involving an OH vacancy is stable, but for larger values the mechanism leading to the formation of HSiO4 is Stable. The other mechanisms considered are unstable.