title: Interstitial incorporation of plutonium into a low-dimensional potassium borate.
abstract: The molten boric acid flux reaction of PuBr(3) with KBO(2) at 200 °C results in the formation of large light-yellow crystals of K[B(5)O(7)(OH)(2)]·H(2)O:Pu(4+). Single-crystal X-ray diffraction experiments on the Pu-doped K[B(5)O(7)(OH)(2)]·H(2)O demonstrate two features: (1) K[B(5)O(7)(OH)(2)]·H(2)O:Pu(4+) adopts a one-dimensional borate chain structure with void spaces between the chains. (2) The doping plutonium atoms do not reside on the potassium sites. The latter are not fully occupied. Both laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy-dispersive spectrometry analyses indicate that plutonium atoms are uniformly distributed in crystals of K[B(5)O(7)(OH)(2)]·H(2)O with an atomic K:Pu ratio of approximately 65:1 measured by LA-ICP-MS. UV-vis-NIR spectra taken from both freshly made and one day old crystals show that the plutonium present within the crystals is predominantly characterized by Pu(IV). A small amount of Pu(III) is also present initially, but slowly oxidized to Pu(IV) via interaction with oxygen in the air. X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopic measurements confirm that plutonium is mainly present as a form similar to that of a PuO(2) cluster. The combined results suggest that the clusters containing Pu(IV) ions are uniformly distributed in the void spaces between the borate chains.
authors.affiliation: Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States.
authors.forename: Shuao
authors.initials: S
authors.lastname: Wang
authors.forename: Juan
authors.initials: J
authors.lastname: Diwu
authors.forename: Antonio
authors.initials: A
authors.lastname: Simonetti
authors.forename: Corwin H
authors.initials: CH
authors.lastname: Booth
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Albrecht-Schmitt
mesh_terms: D001881:Borates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011005:Plutonium / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D013054:Spectrophotometry, Atomic
chemical_list: D001881:Borates; D011005:Plutonium; D011188:Potassium