Digging into the Intrinsic Negative Thermal Expansion of Uranium Tetrafluoride.

The intrinsic negative thermal expansion of UF below room temperature was examined. A redetermination of the structure of UF by single-crystal X-ray diffraction at 100, 200, and 300 K accompanied by an evaluation of the atomic displacement parameters (ADPs) of the F atoms was performed. The structure of UF was described as the stacking of two subnetworks, respectively, constituted by the U(1) and U(2) atoms.

Synthesis and Morphological Control of UOF Particulates.

Uranium-based microspheres are of interest due to their potential applications as targets for medical isotopes production, as fuel for nuclear reactors, and as standardized materials for nuclear forensics. Here, for the first time, UOF microspheres (1-2 μm) have been prepared from the reaction between UO microspheres and AgHF in an autoclave. In this preparation, a new fluorination method has been applied, and HF-produced from the thermal decomposition of AgHF and NHHF-was used as the fluorinating agent.

Synthetic diversity in the preparation of metallic uranium.

Uranium metal is associated with several aspects of nuclear technology; it is used as fuel for research and power reactors, targets for medical isotope productions, explosive for nuclear weapons and precursors in synthetic chemistry. The study of uranium metal at the laboratory scale presents the opportunity to evaluate metallic nuclear fuels, develop new methods for metallic spent fuel reprocessing and advance the science relevant to nuclear forensics and medical isotope production. Since its first isolation in 1841, from the reaction of uranium chloride and potassium metal, uranium metal has been prepared by solid-state reactions and in solution by electrochemical, chemical and radiochemical methods.

Thermal Analysis of Benzotriazolium Perrhenate and Its Implication to Rhenium Metal.

The thermal analysis behavior of CHN[ReO] was studied by simultaneous thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) up to 700 °C under argon. Such analysis afforded rhenium metal, which was characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. XRD peak broadening due to crystallite size and lattice strain was analyzed by both Williamson-Hall (W-H) and Debye-Scherrer (D-S) methods.