A detailed structural characterization of quartz on heating through the α-β phase transition
A detailed structural characterization of quartz on heating through the α-β phase transition
复制标题
DOI：
10.1180/002646101750377524
复制
发表时间：
2001-08-01
影响因子：
2.7
通讯作者：
Dove, MT
中科院分区：
文献类型：
--
作者：
Tucker, MG;Keen, DA;Dove, MT
总中子散射测量。用改进的反蒙特卡罗模拟方法来解释长程晶序，用来描述石英结构随温度变化的行为。报告了两个关键的观察结果。第一。在长程和短程结构关联中都观察到了与位移α-β相变相关的对称性变化。其次，结构的一些方面。例如Si-O键长和热致动力学无序，后者位于相变的显著下方，对相变相对不敏感。这些结果被用来修正β相无序的x域模型和相变的经典软模图像过于简单化。相反，有人认为，结构行为最好的描述是它对低频、高振幅振动模式的响应能力。这一观点得到了额外的单晶弥散中子散射测量的支持。
Total neutron scattering measurements. analysed using a modification of the reverse Monte Carlo modelling method to account for long-range crystallographic order, have been used to describe the temperature-dependent behaviour of the structure of quartz. Two key observations are reported. First. the symmetry change associated with the displacive alpha-beta phase transition is observed in both the long-range and short-range structural correlations. Secondly, some aspects of the structure. such as the Si-O bond length and the thermally-induced dynamic disorder, the latter of which sets in significantly below the transition, are relatively insensitive to the phase transition. These results are used to shorn that the x-domain model of the beta -phase disorder is inappropriate and that the classical soft-mode picture of the phase transition is too simplistic. Instead, it is argued that the structural behaviour is best described in terms of its ability to respond to low-frequency, high-amplitude vibrational modes. This view is supported by additional single-crystal diffuse neutron scattering measurements.