Experimental Visualization of Chemical Bonding and Structural Disorder in Hydroxyapatite through Charge and Nuclear-Density Analysis
Experimental Visualization of Chemical Bonding and Structural Disorder in Hydroxyapatite through Charge and Nuclear-Density Analysis
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DOI：
10.1021/jp208746y
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发表时间：
2011-11
影响因子：
3.7
通讯作者：
M. Yashima;Y. Yonehara;H. Fujimori
中科院分区：
文献类型：
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作者：
M. Yashima;Y. Yonehara;H. Fujimori
羟基磷灰石钙(HAp, Ca10（PO4)6(OH)2）是骨骼和牙齿的主要无机成分、生物活性物质和质子（H+）导体。然而，HAp的化学键和结构紊乱尚不清楚。本文报道了在298和673 K时HAp的电荷密度和核密度的精确分布。目前的结果清楚地证明了共价的P - O和O - H键，更多的离子Ca-O键，以及HAp中从P原子到O原子和从H原子到O原子的电荷转移。研究表明，羟基磷灰石的六方-单斜相转变伴随着OH -离子的位置和取向排序、PO4四面体的倾斜和Ca的位移。在六边形HAp中，质子沿c轴的扩散路径被可视化。我们预计，可视化的化学键和结构紊乱将大大有助于我们理解生物矿物，反应，生物有机体，以及在HAp基质子导体中的扩散过程。
Calcium hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the principal inorganic component of bone and teeth, bioactive material, and proton (H+) conductor. However, the chemical bonding and structural disorder of HAp are unclear. Here we report precise charge- and nuclear-density distributions of HAp at 298 and 673 K. The present results clearly demonstrate the covalent P–O and O–H bonds, more ionic Ca–O bonds, and the charge transfers from P to O atoms and from H to O atoms in HAp. This work shows that the hexagonal–monoclinic phase transition of HAp is accompanied by the occupational and orientational ordering of OH– ions, the tilting of the PO4 tetrahedron, and the Ca displacements. Diffusion paths of proton are visualized along the c-axis in hexagonal HAp. We anticipate that the visualization of chemical bonding and structural disorder of HAp will contribute greatly to our understanding of biominerals, reactions, biological organisms, and the diffusion process in HAp-based proton conductors.