X射线形貌法观察空间电荷缀饰的α—LiIO3单晶的缺陷

实验观察到:α-LiIO₃单晶在c向静电场作用下,与c轴平行的观察面上X射线衍射形貌图有明显的变化。去掉电场,形貌图又复原。此种变化和复原都有个弛豫过程。形貌图形的变化与外电压的极性和大小有关,而基本上与辐射波长无关。静电场下,形貌图上显现的是空间电荷缀饰的晶体的宏观缺陷。即加静电场后,空间电荷在缺陷周围富集,增大了缺陷处的晶格畸变,使原来观察不到的缺陷显示了出来。 关键词：

X-RAY TOPOGRAPHICAL STUDY ON DEFECTS IN α-LiIO3 DECORATED BY SPACE CHARGE DUE TO THE APPLIED DC FIELDS

The diffraction contrast in the X-ray topographs, taken for the crystal face parallel to the c-axis of the α-LiIO₃ single crystals, appears to change remarkably under the action of an applied DC field along the c axis. The contrast in the topographs is restored after the removal of the applied field. After either turning on or turning off the DC voltage, relaxation processes are observed in both the change and the restoration of the diffraction contrast in the X-ray topographs. The change of the contrast depends on the polarity and magnitude of the applied voltage, but appears to be independent of the wave length of the X-ray.The X-ray topographs taken under the condition that a DC field is applied to the crystal displays the macroscopic crystal defects decorated by the space charges. In other words, we can observe the originally undetectable defects, while the space charges accumulate on the crystal defects, the local lattice distortion around the defects is enhanced.