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Title: Synthesis, characterization and thermochemistry of Cs-, Rb- and Sr-substituted barium aluminium titanate hollandites

Journal Article · · Journal of Nuclear Materials

Titanate hollandites are of considerable interest for immobilization of radioactive Cs, its daughter product Ba and related radionuclides Rb and Sr. In this work, we synthesized three hollandites, Ba1.18Cs0.21Al2.44Ti5.53O16, Ba1.17Rb0.19Al2.46Ti5.53O16 and Ba1.14Sr0.10Al2.38Ti5.59O16, using sol–gel methods. Rietveld analysis of synchrotron XRD data shows that they adopt the tetragonal structure (space group I4/m), and their cell parameters increase with increasing cation size (Sr2+ → Rb+ → Cs+). Standard enthalpies of formation of these hollandites were determined from drop solution calorimetric measurements with lead borate as the solvent at 973 K. Their formation enthalpies are similar, consistent with the occurrence of extensive cation substitutions in hollandites. Further energetic analysis with respect to BaTiO3 and SrTiO3 perovskites and other oxides reveals decreased thermodynamic stability from Cs- to Rb- to Sr-hollandite. Lastly, this trend is consistent with the phase assemblage observed in Synroc, where Cs+, Rb+ and Ba2+ enter into hollandite, whereas Sr2+ occurs in perovskite.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC52-06NA25396; AC02-06CH11357
OSTI ID:
1471328
Alternate ID(s):
OSTI ID: 1246584
Report Number(s):
LA-UR-14-29122
Journal Information:
Journal of Nuclear Materials, Vol. 459, Issue C; ISSN 0022-3115
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 23 works
Citation information provided by
Web of Science

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Cited By (6)

Thermodynamic assessment of the hollandite high‐level radioactive waste form journal April 2019
Compositional control of tunnel features in hollandite-based ceramics: structure and stability of (Ba,Cs)1.33(Zn,Ti)8O16 journal September 2018
Structural Evolution in Hollandite Solid Solutions Across the A‐Site Compositional Range from Ba 1.33 Ga 2.66 Ti 5.34 O 16 to Cs 1.33 Ga 1.33 Ti 6.67 O 16 journal August 2016
Compositional control of radionuclide retention in hollandite‐based ceramic waste forms for Cs‐immobilization journal December 2018
An Interdisciplinary View of Interfaces: Perspectives Regarding Emergent Phase Formation journal October 2017
Sample seal-and-drop device and methodology for high temperature oxide melt solution calorimetric measurements of PuO 2 journal April 2019