X-ray study of neutron-irradiated LiF crystals

The nature of defects produced in LiF crystals by neutron-irradiation for a dose of ∼10 18 nvt at different temperatures was studied by X-ray diffraction. Large lattice expansion and small change of the line-width of the diffraction profile were observed in the crystal irradiated at about 0°C, while small change of the lattice parameter and large broadening of the line-width were observed in the crystal irradiated at 80 K. It was concluded that (1) the defects produced by neutron-irradiation at about 0°C were point-like and distributed homogeneously; (2) the majority of the defects produced by the irradiation at 80 K were of zone type and the amount of point-like defects was small; (3) both types of defects were produced at intermediate temperatures between the above two.