-
本文根据(1)在偏振锥光下,用显微镜观察到α-LiIO3单晶中层状缺陷在静电场作用下的变化;(2)静电场对a-LiIO3单晶的X射线形貌象的影响;(3)用X射线双晶衍射测得α-LiIO3单晶晶格参数的不均匀性,指出α-LiIO3单晶在静电场作用下中子衍射增强现象是由于晶体中的空间电荷(载流子、杂质离子和空位)在宏观尺度缺陷处富集,造成晶格参数有一定梯度。我们对通常计算中子布喇格散射截面的玻恩近似,引入消光修正,得到畸变晶格中子衍射强度公式,可以解释文献[4—6]中观察到的各种现象。We have noticed in α-LiIO3 single crystals the following experimental facts: (1) Using the conoscopic observation method, it was found the contrast of layer imperfections increasing with the strength of a dc field. (2) Changes take place in the x-ray topography under the action of a dc field. (3) The grown-in spatial variation of lattice parameters were found and measured by an x-ray double-crystal spectrometer. Based on these observations, we infer that space charges (carriers, impurity ions and vacancies) are accumulated at the defects of macroscopic scale, which in turn produces a gradient of lattice parameters under the action of a dc field. We calculated the neutron Bragg scattering cross section for a distorted single crystal using the Born approximation and taking into account the extinction at the same time. Therefrom, the enhancement of diffraction in an α-LiIO3 crystal under the action of a dc field were qualitatively interpreted with good agreement.
[1] -
[1]
计量
- 文章访问数: 6956
- PDF下载量: 395
- 被引次数: 0