4 by Carbochlorination of U ₃ O ₈ and Solid-State Halogen Exchange Reaction]]>

摘要

Uranium tetrafluoride was synthesized using a novel method, which consists of a combination of carbochlorination reaction between a mixture of U _( 3 ) O _( 8 ) and sucrose carbon with chlorine, and a solid-state halogen exchange reaction between the products of the carbochlorination reaction and sodium fluoride. The thermodynamic feasibility to produce the halogen exchange reaction between UCl _( 4 ) and NaF was analyzed. Reactions are favorable in standard conditions, even at low temperature. We have prepared a mixture of UCl _( 4 ) and UCl _( 2 ) O _( 2 ) by U _( 3 ) O _( 8 ) treatment in Cl _( 2 ) atmosphere with presence of sucrose carbon at 900?°C. UCl _( 4 ) and UCl _( 2 ) O _( 2 ) were obtained as a condensed product, which was collected in a quartz capsule containing NaF. The capsules were sealed after several repeated stages of argon purges and mechanic vacuum. Subsequently, they were treated at 300–350?°C for 2?h. We obtained that when NaF is the limiting reagent, the solid product of the thermal treatment of the capsules consists in a mixture of UF _( 4 ) and NaCl. Solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy, and energy dispersive X-ray spectroscopy. Gaseous products were identified by Fourier-transform infrared spectroscopy.