Magnetism of radiation-damaged LiF

Abstract

The absolute magnetic susceptibility of lithium fluoride single crystals, irradiated with thermal neutrons, was found to consist of three parts: (1) a diamagnetic part, χ d = − 0.408 × 10 −6 emu/g, due to the normal LiF matrix; (2) a temperature-dependent paramagnetic part, obeying the Curie law, attributed to unpaired electrons; and (3) a temperature-independent paramagnetic part arising from the presence of metallic lithium. The data obtained on crystals irradiated to doses between 8 × 10 13 and 8 × 10 18 neutrons cm 2 are discussed from the point of view of radiation damage. Optical absorption, X-ray, and density measurements were performed on samples of known susceptibility. These data as well as those available in the literature were used to correlate all of the observed processes. The radiation damage phenomena can be understood qualitatively if one assumes that primary defects are created continuously during neutron irradiation. The various physical effects are then explained by the ways in which those defects can agglomerate.