Disorder and successive structure transitions in the tridymite forms of SiO2
Disorder and successive structure transitions in the tridymite forms of SiO2
复制标题
SiO2 鳞石英形式的无序和连续结构转变
DOI：
10.1007/bf00202255
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发表时间：
1995
影响因子：
1.4
通讯作者：
K. Kihara
中科院分区：
文献类型：
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作者：
K. Kihara
Disorder models of oxygen positions in P63/ mmc, C2221 and P212121 tridymites were given in applying geometrical and lattice dynamical calculations. Sixmembered rings of rigid SiO4 units are all collapsed in these forms; with silicon atoms fixed, SiO4 units can take six different orientations in forming tridymite frameworks in both the P63/mmc and C2221 forms, and three orientations in the P212121 form. Atomic distances and angles obtained from the distance least-squares method are about equal for the three forms: 〈Si-O〉 (mean Si-O) = 1.611 Å, 〈O-O〉 = 2.629 Å, and 〈Si-O-Si〉 = 147°. Domain formation models are given for the three forms.The tridymite framework structures may possibly undergo lattice vibrations with low frequencies in two kinds of pair-wise rotational modes of SiO4 units joined by the apical oxygen atoms, at the Γ-point: one is around 〈100〉 (or 〈210〉 for the hexagonal case), and the other is around 〈010〉. As temperature approaches the hexagonal-orthorhombic transition from below, the rotational mode around 〈100〉 remarkably softens at the Γ-point. The behavior of the atoms at the hexagonal-orthorhombic transition is explained in terms of a coupled softening of the two rotational modes of neighboring local domains in different orientations.
Kuniaki KIHARA：“石英中原子各向异性温度因子的晶格动力学计算以及 β-石英的结构。”
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