Geological Society of America

T65 Radiation Effects, Mineralogy, and Materials Science of Actinides II: In Honor of Rodney C. Ewing, 2015 Roebling Medalist

Sunday, 1 November 2015
1:30 PM - 5:30 PM
Room 317

MATERIALS PROPERTIES OF SYNTHETIC URANYL VANADATE MINERAL ANALOGUES POSSESSING THE FRANCEVILLITE ANION TOPOLOGY

Paper number: T65-9
Program: Technical Sessions
Time: 3:35 PM – 3:50 PM

Authors

Tyler L. Spano Presenting Author
University of Notre Dame, Notre Dame, IN
Megan K. Dustin
Stanford University, Stanford, CA
Madison Turner
University of Maryland, College Park, MD
Zoë Simms
University of Notre Dame, Notre Dame, IN
Peter C. Burns
University of Notre Dame, Notre Dame, IN

Abstract

Naturally occurring uranyl vanadate mineral species are relatively insoluble and widely disseminated within U ore deposits, mine and mill tailings, and are capable of forming in a potential geologic repository for used nuclear fuel. Composed of infinite sheets containing V⁵⁺O₅square pyramids and uranyl pentagonal bipyramids, the general formula of these materials is M_x(UO₂)₂V₂O₈∙nH₂O where M is a mono-, di-, or tri-valent cation and n is 1-5.

Ion exchange properties of carnotite-like uranyl vanadate minerals have been explored using mild hydrothermal synthetic methods. The structural properties of the resulting mineral analogue crystals and powders were elucidated using powder and single crystal X-ray diffraction. Raman spectroscopy was used to confirm and examine bonding behavior in and between structural units and interstitial complexes in synthesized materials. Approximate mineral formulae were calculated from concentration data obtained from inductively coupled plasma optical emission spectroscopic methods.

Structural, vibrational, and chemical properties of obtained synthetic materials were related to the identity of incorporated cation species. Changes in interplanar spacing of uranyl vanadate sheets were observed. A linear relationship between cation size and position of vibrational modes in Raman spectra was established when lanthanide cations populate interlayer space. Structural and materials properties will be related to thermochemical stability. Understanding and interpreting a diverse range of structural and chemical data is necessary to fully understand and predict the behavior of uranyl vanadate mineral species in geologic and anthropogenic regimes.