The magnetic susceptibility of some carbides of uranium and thorium

Abstract

The magnetic susceptibilities of the monocarbides and dicarbides of both thorium and uranium have been measured at room temperature, and the temperature variation of susceptibility has also been determined in the range 90-1100°K for both thorium and uranium carbides. The susceptibilities of uranium carbide-rich, uranium carbide-thorium carbide compounds have also been measured in the same temperature range for specimens of nominal composition 1, 3, 8, 15 and 20% thorium carbide by weight. All the compounds show little variation of susceptibility in the range investigated. The susceptibility of each of the mixed carbides and uranium carbide is independent of temperature in the low temperature region. The slight curvature observed in this region for thorium carbide and thorium dicarbide is attributed to the presence of ferromagnetic impurity; the measurements do not fit a Curie-Weiss law. The variation of susceptibility may be explicable in terms of a band model, but at present the data are not sufficiently extensive.