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Title: Comparison of structure, morphology, and leach characteristics of multi-phase ceramics produced via melt processing and hot isostatic pressing

Melt processing of multi-phase ceramic waste forms offers potential advantages over traditional solid-state synthesis methods given both the prevalence of melters currently in use and the ability to reduce the possibility of airborne radionuclide contamination. In this work, multi-phase ceramics with a targeted hollandite composition of Ba 1.0Cs 0.3Cr 1.0Al 0.3Fe 1.0Ti 5.7O 16 were fabricated by melt processing at 1675 °C and hot isostatic pressing (HIP) at 1250 and 1300 °C. X-ray diffraction analysis (XRD) confirmed hollandite as the major phase in all specimens. Zirconolite/pyrochlore peaks and weaker perovskite reflections were observed after melt processing, while HIP samples displayed prominent perovskite peaks and low-intensity zirconolite reflections. Melt processing produced specimens with large (>50 μm) well-defined hollandite grains, while HIP yielded samples with a more fine-grained morphology. Elemental analysis showed “islands” rich in Cs and Ti across the surface of the 1300 °C HIP sample, suggesting partial melting and partitioning of Cs into multiple phases. Photoemission data revealed multiple Cs 3d spin-orbit pairs for the HIP samples, with the lower binding energy doublets likely corresponding to Cs located in more leachable phases. Among all specimens examined, the melt-processed sample exhibited the lowest fractional release rates for Rb and Cs. However,more » the retention of Sr and Mo was greater in the HIP specimens.« less
Authors:
 [1] ;  [2] ; ORCiD logo [2] ;  [3] ;  [1]
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
  2. Clemson Univ., SC (United States)
  3. Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia)
Publication Date:
Report Number(s):
SRNL-STI-2017-00651
Journal ID: ISSN 0022-3115; PII: S0022311517314241
Grant/Contract Number:
AC09-08SR22470
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 502; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1427454