AN ANALYSIS OF THE STRUCTURAL CHARACTERISTICS OF HOLLANDITE COMPOUNDS
AN ANALYSIS OF THE STRUCTURAL CHARACTERISTICS OF HOLLANDITE COMPOUNDS
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DOI：
10.1107/s0108768186098294
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发表时间：
1986-06-01
期刊：
影响因子：
--
通讯作者：
CHEARY, RW
中科院分区：
文献类型：
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作者：
CHEARY, RW
七个SYNROC相关的钡hollandites Bax（Ma+ Ti ~（4+））801 6的中子粉末衍射数据已被细化，以建立各种三价离子，如Fe，Al和Ga如何改变晶体结构，并使其易于放射性废物取代。特别注意的是在隧道网站的环境和性质的单斜-四斜变换在奥朗德的变化。早期改进的结构数据包括在分析中。晶胞体积、唯一轴的晶格参数、O八面体体积和隧道腔体积都主要受八面体位阳离子的大小控制。当隧道阳离子不再能够支撑坍塌到隧道离子上的隧道壁时，发生从四斜对称到单斜对称的变化，其中壁之间的角连接充当铰链。
Neutron powder diffraction data for seven SYNROC-related barium hollandites Bax (Ma+ Ti4+) 8Ol6 have been refined to establish how various trivalent ions such as Fe, A1 and Ga change the crystal structure and predispose it to radwaste substitution. Particular attention is given to changes in the environment of the tunnel sites and the nature of the monoclinic-tetragonal transformation in hollandites. Structural data from earlier refinements are included in the analysis. The unit-cell volume, the lattice parameter of the unique axis, the O octahedral volume and the tunnel-cavity volume are all controlled primarily by the size of the octahedral-site cations. The change from tetragonal to monoclinic symmetry occurs when the tunnel cations are no longer able to support the tunnel walls which collapse onto the tunnel ions with the corner linkages between the walls acting as hinges.