Formation, stability and crystal structure of mullite-type Al6−xBxO9
Formation, stability and crystal structure of mullite-type Al6−xBxO9
复制标题
DOI：
10.1016/j.jssc.2016.08.018
复制
发表时间：
2016-11
影响因子：
3.3
通讯作者：
K. Hoffmann;T. Hooper;M. Murshed;O. Dolotko;Z. Révay;A. Senyshyn;H. Schneider;J. Hanna;T. Gesing;R. Fischer
中科院分区：
文献类型：
--
作者：
K. Hoffmann;T. Hooper;M. Murshed;O. Dolotko;Z. Révay;A. Senyshyn;H. Schneider;J. Hanna;T. Gesing;R. Fischer
用粉末衍射和光谱方法研究了莫来石型Al 6 − xBxO 9化合物。这种结构的主链是由AlO-和BO-多面体交联的边缘连接的AlO 6八面体链。Rietveld精化表明，a和格点参数可以很好地分辨，从而表示正交度规.晶格参数的连续减小最明显的是在垂直方向，表明Al 6 − xBxO 9为固溶体，1.09≤x≤2。11BMASNMR谱和基于4K下中子衍射数据的傅立叶计算证实了硼优先以三重配位。距离最小二乘建模进行模拟的本地几何形状，避免长的B-O距离连接两个八面体链的平面BO 3基团产生分裂位置的氧原子和一个强大的扭曲的八面体链。晶格热膨胀采用Grüneisen一阶状态方程Debye-Einstein-Anharmonicity模型计算。
Mullite-type Al6−xBxO9compounds were studied by means of powder diffraction and spectroscopic methods. The backbones of this structure are chains of edge-connected AlO6octahedra crosslinked by AlO- and BO-polyhedra. Rietveld refinements show that theaandblattice parameters can be well resolved, thus representing an orthorhombic metric. A continuous decrease of the lattice parameters most pronounced inc-direction indicates a solid solution for Al6−xBxO9with 1.09≤x≤2. A preference of boron in 3-fold coordination is confirmed by11B MAS NMR spectroscopy and Fourier calculations based on neutron diffraction data collected at 4 K. Distance Least Squares modeling was performed to simulate a local geometry avoiding long B-O distances linking two octahedral chains by planar BO3groups yielding split positions for the oxygen atoms and a strong distortion in the octahedral chains. The lattice thermal expansion was calculated using the Grüneisen first-order equation of state Debye-Einstein-Anharmonicity model.