Structure and triclustering in Ba-Al-O glass
Structure and triclustering in Ba-Al-O glass
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Ba-Al-O 玻璃的结构和三簇
DOI：
10.1103/physrevb.85.064201
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发表时间：
2012
影响因子：
3.7
通讯作者：
Skinner L
中科院分区：
文献类型：
--
作者：
Skinner L
采用无容器空气动力悬浮和激光加热方法研究了（BaO）（AlO）系统（）的玻璃形成能力。发现主要的玻璃形成区域出现在0.40（2）± 0.48（2）处，在该区域没有足够的氧形成理想的共角Al O四面体网络，其中氧原子是双重配位的，而在低共熔成分周围的另一个狭窄的玻璃形成区域在0.62（2）处。选择了0.4的玻璃作为研究对象，采用中子衍射和X射线衍射相结合的方法，结合分子动力学和逆蒙特卡罗方法建立了详细的原子模型。结果表明，该结构主要基于角共享四面体AlO基序，其中三簇（由三个四面体Al原子共享一个顶点形成的OAl单元）起着不可或缺的作用，这些构型中涉及多达21个氧原子.钡离子与平均7.4个氧原子结合，其中大部分是双配位的桥氧原子。与钙相比，钡的较大尺寸缩小了碱土铝酸盐中的玻璃形成组合物的范围，使得主要玻璃形成范围对应于其中缺氧Al-O网络通过形成三簇而稳定的状态。
Glass-forming ability in the (BaO)(AlO)system () was investigated by using the containerless aerodynamic levitation and laser-heating method. The main glass-forming region was found to occur for 0.40(2)0.48(2), where there is insufficient oxygen to form an ideal network of corner-sharing AlOtetrahedra in which the oxygen atoms are twofold coordinated, with another narrow glass-forming region at0.62(2) around the eutectic composition. The glass corresponding to0.4 was chosen for further investigation by using both neutron and x-ray diffraction, and a detailed atomistic model was built by applying a combination of molecular dynamics and reverse Monte Carlo methods. The results show a network structure based predominantly on corner-sharing tetrahedral AlOmotifs in which triclusters (OAlunits formed by three tetrahedral Al atoms sharing a common vertex) play an integral part, with as many as 21of the oxygen atoms involved in these configurations. The barium ions bind to an average of 7.4 O atoms, most of which are twofold-coordinated bridging oxygen atoms. The larger size of barium compared to calcium narrows the range of glass-forming compositions in alkaline-earth aluminates such that the main glass-forming range corresponds to a regime in which an oxygen-deficient Al-O network is stabilized by the formation of triclusters.