Magnetic properties of the trichlorides, tribromides, and triiodides of U(III), Np(III), and Pu(III)

Abstract

Magnetic susceptibilities of uranium, plutonium, and neptunium trichlorides, tribomides, and triiodides were measured from 2.7°K to as high as 240°K with a vibrating-sample magnetometer at applied fields up to 12 kOe. Antiferromagnetic transitions were observed in UCl3, TN=22.0±1.0°K; in UBr3, TN=15.0±0.5°K; in UI3, TN=3.4±0.2°K; and in PuCl3, TN=4.5±0.5°K. A ferromagnetic transition at Tc=4.75±0.1°K was found for PuI3, and a slight hysteresis was measured at 2.7°K. Temperature-independent paramagnetism was observed for NpCl3 below 50°K, for α-NpBr3 below 30°K, and for NpI3 below 15°K. All these latter compounds, and PuBr3, exhibited Curie-Weiss paramagnetism at higher temperatures, with effective moments near the free-ion moments. The experimental magnetic susceptibility of PuCl3 from 10 to 100°K agrees with the susceptibility calculated from crystal field energy levels and wavefunctions.

Electrochemical behaviour of neptunium in the molten LiCl–KCl eutectic

“…According to the magnetic measurements, the oxidation states of NpCl 3 and NpCl 4 were clearly distinguished and there was no doubt about the nature of the compounds. These results are in agreement with literature for NpCl 3 [18] and NpCl 4 [19,20].…”

“…(18), are reported in Table 4. The number of exchanged electrons ranges between 2.6 at 430°C and 2.95 at 550°C which is roughly in agreement with a three-electron redox system for the Np 3+ /Np 0 transition.…”

Magnetic Properties of Organometallic and Coordination Compounds of Plutonium

“…The magnetic moment between 90 and 300 K is about ^eff = y^" and decreases at higher temperature. An antiferromagnetic transition was found for PUCI3 at 4.5 K, whereas Pul3 orders ferromagnetically at 4.75 K (28). PuBr3 shows a pure Curie behavior (28).…”

“…An antiferromagnetic transition was found for PUCI3 at 4.5 K, whereas Pul3 orders ferromagnetically at 4.75 K (28). PuBr3 shows a pure Curie behavior (28). The magnetism of PuCl3 was fitted by using the van Vleck formula assuming the energy levels of Pu 3+ in LaCl 3 , Ei = 13 and E 2 = 77 cm" 1 .…”

“…The magnetism of PuCl3 was fitted by using the van Vleck formula assuming the energy levels of Pu 3+ in LaCl 3 , Ei = 13 and E 2 = 77 cm" 1 . A TIP contribution of 236 x 10" 6 emu for the 6 H7/ 2 was also included (21,28).…”