A molecular dynamics model of the atomic structure of dysprosium alumino-phosphate glass
A molecular dynamics model of the atomic structure of dysprosium alumino-phosphate glass
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镝铝磷酸盐玻璃原子结构的分子动力学模型
DOI：
10.1088/0953-8984/21/7/075102
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
R. J. Newport
中科院分区：
文献类型：
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作者：
Richard A. Martin;G. Mountjoy;R. J. Newport
采用分子动力学方法研究了磷酸盐玻璃DyAl 0.30P3.05O 9.62中镝的相对分布。MD模型已被直接与中子衍射获得的实验数据进行了比较，使详细的比较超出了总的结构因子水平。分子动力学模拟给出了3.80（5）和6.40（5）Ω的相关性，相对配位数为0.8（1）和7.3（5），从而提供了这些玻璃中少数稀土聚集的证据。最近邻Dy-O峰出现在2.30 nm处，每个Dy原子平均具有5.8个最近邻氧原子。MD模拟与基于互连的PO 4四面体的磷酸盐网络模型一致，其中网络改性剂Dy 3+的添加通过P-（O）-P键的断裂使磷酸盐网络解聚，同时使四面体单元保持完整。铝在网络中的作用已被明确考虑，铝被发现主要是（78%）四面体配位。事实上，所有四个铝键被发现是P（通过氧原子）与可忽略的量的Al-O-Dy键存在。这提供了一个重要的洞察Al添加剂在改善这些玻璃的机械性能的作用。
Molecular dynamics (MD) has been used to identify the relative distribution of dysprosium in the phosphate glass DyAl0.30P3.05O9.62. The MD model has been compared directly with experimental data obtained from neutron diffraction to enable a detailed comparison beyond the total structure factor level. The MD simulation gives correlations at 3.80(5) and 6.40(5) Å with relative coordination numbers of 0.8(1) and 7.3(5), thus providing evidence of minority rare-earth clustering within these glasses. The nearest neighbour Dy–O peak occurs at 2.30 Å with each Dy atom having on average 5.8 nearest neighbour oxygen atoms. The MD simulation is consistent with the phosphate network model based on interlinked PO4 tetrahedra where the addition of network modifiers Dy3+ depolymerizes the phosphate network through the breakage of P–(O)–P bonds whilst leaving the tetrahedral units intact. The role of aluminium within the network has been taken into explicit account, and Al is found to be predominantly (78%) tetrahedrally coordinated. In fact all four Al bonds are found to be to P (via an oxygen atom) with negligible amounts of Al–O–Dy bonds present. This provides an important insight into the role of Al additives in improving the mechanical properties of these glasses.