X‐ray diffraction, differential scanning calorimetry and evolved gas analysis of aged plutonium tetrafluoride (PuF4)

• Published in: Journal of radioanalytical and nuclear chemistry 2021-08, Vol.329 (2), p.741-756
• Main Authors: Wayne, David M., Stritzinger, Jared T., Casella, Amanda J., Sweet, Lucas E., Corbey, Jordan F., Garcia, Daniel J., Wylie, E. Miller, Tandon, Lav, Olson, Angela C., Rim, Jung Ho
• Format: Article
• Language: English
• Subjects: Annealing; Calorimetry; Chemistry; Chemistry and Materials Science; Damage; Dehydration; Diagnostic Radiology; Differential scanning calorimetry; Diffraction; evolved gas analysis; Exothermic reactions; Fluorides; Fluorine; Gas analysis; Hadrons; Heat measurement; Heavy Ions; Hydrofluoric acid; Inorganic Chemistry; Nuclear Chemistry; Nuclear Physics; Physical Chemistry; Plutonium; Plutonium dioxide; Plutonium fluorides; plutonium tetrafluoride; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; radiation damage; thermal analysis; Thermogravimetric analysis; X-ray diffraction; X-rays
• ISSN: 0236-5731; 1588-2780
• DOI: 10.1007/s10967-021-07810-z

A 30 year-old PuF 4 sample consisting of brown powder (PuF 4 -b) and pink granules (PuF 4 -p) was analyzed. X-ray diffraction shows the bulk is comprised of three compounds: PuF 4 , PuO 2 , and PuF 4 ·1.6H 2 O. Broadening of PuF 4 XRD peaks suggests possible α -damage. After annealing at 650 °C, crystalline PuF 4 and PuO 2 remain. Thermogravimetric analysis and differential scanning calorimetry—with simultaneous evolved gas analysis—of the separated PuF 4 -p and PuF 4 -b components reveal a distinct sequence of reactions. Dehydration occurs between ~ 90 and 300 °C. Exothermic annealing of the α -damage occurs in two stages: at 350–355 °C and at 555–558 °C. Hydrofluoric acid, fluorine and helium desorb during the first exotherm. Above 700 °C, PuF 4 reacts with PuO 2 , resulting in oxygen release and mass loss.