Mössbauer spectrometry has been widely used to characterize akageneite nanoparticles, however, there are no reports of the application of this technique in akaganeites formed in the presence of arsenic, antimony and mercury. The purpose of this work is to investigate possible changes in the hyperfine parameters of akaganeites due to the presence of the co-precipitated ions, and therefore in the chemical environment of Fe<sup>3+</sup>. Among the results at 300K, it was noticed that the hyperfine parameters were similar for all samples and to those for pure akaganeite. Therefore, it confirms that only akaganeite was precipitated in all experiments. At 77 K, in general, the isomer shift appeared as the less sensitive parameter to the physico-chemical changes experienced by akaganeites co-precipitated with ions, contrarily to the quadrupole shift as well as the hyperfine field. The samples that showed the most significant changes in the quadrupole shifts compared with the value for pure akageneite, were those synthesized in the presence of 60 ppm concentration of Hg, Sb and As. On the other hand, the magnetic hyperfine fields were reduced in all cases compared with that of the pure akageneite, following the order: pure akageneite &gt; 60 ppm Sb ≈ 60 ppm Hg &gt; 60 ppm As. Finally, by using the fitting model proposed by Barrero et al. [2], it was observed that hyperfine fields associated to monoclinic Fe1 and Fe2 sites in the vicinity of unoccupied chloride sites, showed the major variations particularly for those akaganeites co-precipitated with 60 ppm As. The results obtained by other complementary techniques such as X-ray diffraction, Raman and Infrarred spectroscopies and Transmission Electron Microscopy will also be presented and discussed [1].

Mössbauer characterization of co-precipitated akaganeites in presence of antimony, mercury and arsenic

ACS Fall 2021

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