es6b04209_si_001.pdf (32.04 MB)
Download fileIncorporation of Technetium into Spinel Ferrites
journal contribution
posted on 2016-11-09, 00:00 authored by Wayne W. Lukens, Nicola Magnani, Tolek Tyliszczak, Carolyn I. Pearce, David K. ShuhTechnetium
(99Tc) is a problematic fission product for
the long-term disposal of nuclear waste due to its long half-life,
high fission yield, and to the environmental mobility of pertechnetate,
the stable species in aerobic environments. One approach to preventing 99Tc contamination is using sufficiently durable waste forms.
We report the incorporation of technetium into a family of synthetic
spinel ferrites that have environmentally durable natural analogs.
A combination of X-ray diffraction, X-ray absorption fine structure
spectroscopy, and chemical analysis reveals that Tc(IV) replaces Fe(III)
in octahedral sites and illustrates how the resulting charge mismatch
is balanced. When a large excess of divalent metal ions is present,
the charge is predominantly balanced by substitution of Fe(III) by
M(II). When a large excess of divalent metal ions is absent, the charge
is largely balanced by creation of vacancies among the Fe(III) sites
(maghemitization). In most samples, Tc is present in Tc-rich regions
rather than being homogeneously distributed.