静电场作用下α-碘酸锂单晶中子衍射的增强(Ⅱ)

在以前工作的基础上,继续作了以下的实验:(1)在低温条件下测定了α-碘酸锂单晶在静电场中的衍射情况,观察到在～180K以下出现“冻结”现象,即加上电场并不能使衍射增强,撤去原在室温所加的电场后衍射强度也并不减弱;(2)用狭束中子探测了加静电场后晶体的不同部位,观察到衍射增强是体效应而不是表面层效应;(3)测定了低频交变电场对晶体中子衍射强度的影响,衍射束增强的程度随频率的下降而加大,频率在1500Hz时衍射束的增强已不明显。

ENHANCEMENT OF NEUTRON DIFFRACTION INTENSITIES OF α-LiIO3 SINGLE CRYSTALS WITH THE APPLICATION OF A DC FIELD (Ⅱ)

The following investigations have been carried out on the basis of our previous work 1]. The (002) intensities of neutron diffraction from α-LiIO₃ single crystals under a DC or AC field along the c-axis were measured in various eases. (1) With a DC field applied at a temperature below 180 K or so, no enhancement is found to appear. When the DC field is applied at room temperature and the sample then cooled down to 180 K or even lower (e. g liquid nitrogen temperature), the magnitude of the diffraction intensity enhancement initially observed at room temperature remains the same, even after removing the applied voltage. (2) When a narrow neutron beam is scanned across a thicker crystal and a DC field applied, the diffraction intensity enhancement is not limited to the region near the electrodes, but also appears in each scanned region. (3) When a low-frequency AC field is applied, the enhancement decreases as the frequency increases for the same V_s.m.s. Above 1500 c/s the effect becomes negligible.