LiNbO3晶体在75℃附近赝考塞耳线衍射异常

用X射线发散束背反射赝考塞耳线衍射方法发现纯LiNbO₃和扩Ti的LiNbO₃晶体在75℃附近的衍射花样有明显的异常。(11010),(01110),(0118),(1108),(03312),(33012)等衍射面的考塞耳花样出现成对的大范围非断裂的畸变。畸变接近二次对称,对称面为x面。破坏了沿z轴方向的三次对称性。同时发现高角度的衍射面畸变α较小,或不畸变。布喇格角较小的衍射面畸变较甚。 关键词：

THE ANOMALOUS BACK DIFFRACTION PSEUDO-KOSSEL PATTERNS OF LiNbo3 CRYSTAL IN THE VICINITY OF 75℃

It is found that the diffraction, obtained by using X-ray divergent beam technique-back reflection Kossel method, of pure and Ti-diffused LiNbO₃ crystals become abnormal in the vicinity of 75℃.The Pseudo-Kossel lines of such crystal planes as (11010), (01110), (0118), (1108), (03312), (33012), are found to be severely distorted but still continuous. The pattern's distortion shows approximately two-fold symmetry about x-plane and therefore the crystal's triad axis of symmetry along x-direction is destroyed.It is also found that the distortions of pseudo-Kossel lines arising from high Bragg angle diffraction planes are smaller than those arising from lower angle diffraction planes.