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Title: Chemical Trends in Solid Alkali Pertechnetates

Insight into the solid-state chemistry of pure technetium-99 ( 99Tc) oxides is required in the development of a robust immobilization and disposal system for nuclear waste stemming from the radiopharmaceutical industry, from the production of nuclear weapons, and from spent nuclear fuel. However, because of its radiotoxicity and the subsequent requirement of special facilities and handling procedures for research, only a few studies have been completed, many of which are over 20 years old. In this study, we report the synthesis of pure alkali pertechnetates (sodium, potassium, rubidium, and cesium) and analysis of these compounds by Raman spectroscopy, X-ray absorption spectroscopy (XANES and EXAFS), solid-state nuclear magnetic resonance (static and magic angle spinning), and neutron diffraction. The structures and spectral signatures of these compounds will aid in refining the understanding of 99Tc incorporation into and release from nuclear waste glasses. NaTcO 4 shows aspects of the relatively higher electronegativity of the Na atom, resulting in large distortions of the pertechnetate tetrahedron and deshielding of the 99Tc nucleus relative to the aqueous TcO 4 . At the other extreme, the large Cs and Rb atoms interact only weakly with the pertechnetate, have closer to perfect tetrahedral symmetry at the Tc atom,more » and have very similar vibrational spectra, even though the crystal structure of CsTcO 4 is orthorhombic while that of RbTcO 4 is tetragonal. Further trends are observed in the cell volume and quadrupolar coupling constant.« less
Authors:
 [1] ;  [2] ; ORCiD logo [2] ;  [2] ;  [2] ; ORCiD logo [3] ;  [4] ;  [5] ; ORCiD logo [6]
  1. Washington State Univ., Pullman, WA (United States). Dept. of Chemistry; Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. USDOE Office of River Protection, Richland, WA (United States)
  5. Washington State Univ., Pullman, WA (United States). Dept. of Chemistry
  6. Washington State Univ., Pullman, WA (United States). Dept. of Chemistry and Materials Science and Engineering Program and School of Mechanical and Materials Engineering; Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
PNNL-SA-121324
Journal ID: ISSN 0020-1669
Grant/Contract Number:
AC0576RL01830; AC02-05CH11231
Type:
Published Article
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 56; Journal Issue: 5; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1344320
Alternate Identifier(s):
OSTI ID: 1344529; OSTI ID: 1408420