Study of the Magnetic Properties of the Actinide Metals: Th1−xUxPd3

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Abstract
ThPd3, with UPd3, forms a continuous series of solid solutions. These two intermetallic compounds have the hexagonal DO24 structure. We have studied the magnetic susceptibilities of eleven Th1−xUxPd3 alloys (0≤x≤1) at temperatures from 1.4° to 300°K in fields up to 15 kOe and at 4.2°K in fields up to 80 kOe. ThPd3 is diamagnetic and shows a temperature‐independent susceptibility, but the addition of U, even in small amounts, gives rise to a strongly temperature‐dependent paramagnetic susceptibility. The data analyzed in terms of T against 1/χ−χ∞ gives a Curie‐Weiss behavior in the high‐temperature region with 3.35 μB/U atom at low U concentrations; decreasing to 2.6 μB for UPd3. It appears that the U‐5f electrons form a localized moment for low U concentrations. A deviation from a Curie law at around 100°K for all U concentrations is suggested to be due either to crystal field splitting of the U‐5f levels or to the presence of a narrow 5f band. The lack of any indication of an antiferromagnetic transition in the temperature behavior of the susceptibility at high U concentrations and the linearity of the magnetic moment with magnetic field up to 80 kOe for the same alloys, favors the formation of a very narrow 5f band as the U concentration increases and lends support to previous EPR experiments of Gd in UPd3, where a similar conclusion was reached.