The inelastic nature of diffuse X‐Ray scattering near the α‐β transition in quartz
The inelastic nature of diffuse X‐Ray scattering near the α‐β transition in quartz
复制标题
石英中 α-β 转变附近漫 X 射线散射的非弹性性质
DOI：
10.1002/pssb.2220480143
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发表时间：
1971
期刊：
影响因子：
--
通讯作者：
H. Grimm
中科院分区：
文献类型：
--
作者：
K. Bauer;H. Jagodzinski;B. Dorner;H. Grimm
通过中子的非弹性散射，研究了沿[ζ00]方向的扩散X射线散射的起源。发现声子频率是各向异性的，特别是在[ζ00]方向。频率较低的声子会在明显的弥散条纹中引起增强的X射线散射。这很可能是因为驱动α-β跃迁的软光学声子(已被其他作者在Q=0时研究)在[ζ00]方向上变得非常软，并迫使声色散分支向下。测量到的声子在560°C(低于跃迁13°)有很强的衰减，因此在零能量转移处有一个明显的尾巴，但没有观察到预期的静态无序的弹性散射。偏离[ζ00]方向的色散显示一个陡峭的山谷，这解释了垂直于[ζ00]方向的漫射散射的宽度。
By inelastic scattering of neutrons, the origin of diffuse X‐ray scattering along [ζ00] directions has been investigated. Phonon frequencies are found to be anisotropic and especially low for the [ζ00] direction. Phonons with low frequencies cause enhanced X‐ray scattering in pronounced diffuse streaks. It is probable that this occurs because a soft optic phonon, which drives the α‐β transition and which has been investigated at q = 0 by other authors, becomes soft very predominantly for the [ζ00] direction and forces down an acoustic dispersion branch. The measured phonons are strongly damped at 560 °C (13° below the transition) so that there is a remarkable tail at zero energy transfer, but elastic scattering as expected from static disorder was not observed. The dispersion for deviations from the [ζ00] direction shows a steep valley, which explains the width of the diffuse scattering perpendicular to the [ζ00] direction.