Compositional control of radionuclide retention in hollandite-based ceramic waste forms for Cs-immobilization

Mingyang Zhao, Yun Xu, Lindsay Shuller-Nickles, Jake Amoroso, Anatoly I. Frenkel, Yuanyuan Li, Weiping Gong, Kristina Lilova, Alexandra Navrotsky, Kyle S. Brinkman

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Hollandite materials, as a class of crystalline nuclear waste forms, are promising candidates for the immobilization of radioactive elements, such as Cs, Ba, as well as a variety of lanthanide and transition-metal fission products. In this study, three Ga-doped titanate hollandite-type phases, Ba 1.33 Ga 2.67 Ti 5.33 O 16 , Ba 0.667 Cs 0.667 Ga 2 Ti 6 O 16 , and Cs 1.33 Ga 1.33 Ti 6.67 O 16 , were synthesized using a solid-state reaction route. All synthesized phases adopted a single phase tetragonal structure, as determined by powder X-ray diffraction (XRD), and elemental analysis confirmed the measured stoichiometries were close to targeted compositions. Extended X-ray absorption fine structure spectroscopy (EXAFS) was used to determine the local structural features for the framework of octahedrally coordinated cations. EXAFS data indicated that Cs 1.33 Ga 1.33 Ti 6.67 O 16 possessed the most disordered local structure centered around the Ga dopant. The enthalpies of formation of all three hollandite phases measured using high-temperature oxide melt solution calorimetry were found to be negative, indicating enthalpies of formation of these hollandites from oxides are thermodynamically stable with respect to their constituent oxides. Furthermore, the formation enthalpies were more negative and hence more favorable with increased Cs content. Finally, aqueous leaching tests revealed that high Cs content hollandite phases exhibited greater Cs retention as compared to low Cs content hollandite. While preliminary in nature, this work draws attention to the links between the capacity for radionuclide retention, atomistic level structural features and bulk thermodynamic properties of materials.

Original languageEnglish (US)
Pages (from-to)4314-4324
Number of pages11
JournalJournal of the American Ceramic Society
Volume102
Issue number7
DOIs
StatePublished - Jul 2019
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Compositional control of radionuclide retention in hollandite-based ceramic waste forms for Cs-immobilization'. Together they form a unique fingerprint.

Cite this