In situ Raman spectroscopy of samarium ions in molten LiCl-KCl eutectic

Mapping Intimacies ◽

10.1149/osf.io/qpsr3 ◽

2019 ◽

Author(s):

Vickram J. Singh ◽

Christopher D. Bruneau ◽

Dev Chidambaram

Keyword(s):

Raman Spectroscopy ◽

Raman Spectra ◽

Chemical Reduction ◽

Inert Atmosphere ◽

Eutectic System ◽

In Situ Raman Spectroscopy ◽

In Situ Raman ◽

Samarium Chloride ◽

And Behavior

A fiber-based Raman spectroscopy system was commissioned in an inert atmosphere for in situ analysis of high temperature molten salts. Speciation of samarium chloride was studied in the LiCl-KCl eutectic system at 500 °C. Raman spectra indicated trivalent samarium forms an octahedral SmCl63- complex with two detectable vibration modes. Chemical reduction experiments were conducted to investigate the coordination of divalent samarium in the same eutectic salt. The resulting spectra are reported and discussed in terms of complex formation and behavior of divalent samarium ions. Trivalent samarium was electrochemically reduced in situ and Raman spectra obtained were compared with those resulting from chemical reduction experiments. The spectra suggest divalent samarium ions form in LiCl-KCl only temporarily and spontaneously disproportionate into a mixture of trivalent samarium ions and metallic samarium.

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In Situ Raman Spectroscopy as a Tool for Discerning Subtle Structural Differences between Commercial (Ce,Zr)O2-Based OSC Materials of Identical Composition

Catalysts ◽

10.3390/catal10040462 ◽

2020 ◽

Vol 10 (4) ◽

pp. 462

Author(s):

Chrysanthi Andriopoulou ◽

Deb Harris ◽

Hazel Stephenson ◽

Angelos M. Efstathiou ◽

Soghomon Boghosian

Keyword(s):

Raman Spectroscopy ◽

Metal Oxide ◽

Raman Spectra ◽

Mixed Metal Oxide ◽

Oxide Materials ◽

In Situ Raman Spectroscopy ◽

Aqueous Chemistry ◽

Mixed Metal ◽

In Situ Raman

In situ Raman spectroscopy was used at temperatures in the 50–480 °C range under oxidizing (20% O2/He) and reducing (5% H2/He) flowing gas atmospheres to compare the spectra obtained for a series of industrial rare earth doped CexZr1−xO2−δ oxygen storage capacity (OSC) mixed metal oxide materials of identical at % composition, which were prepared by the same chemical synthesis route, in which one synthesis parameter of the aqueous chemistry was slightly varied. The Raman fingerprint of the anionic sublattice is very sensitive to O atom relocations within the bulk of the material matrix and to the pertinent defect topology in each case. A protocol of sequential Raman measurements and analysis was proposed to discern subtle differences between the oxygen vacancy and defect topologies of the examined materials. It can be concluded that for two materials under comparison for their structures, identical Raman spectra are obtained only if the procedures followed for their preparation are identical; a slight variation of one single parameter (e.g., in the aqueous chemistry stage) results in discernible differences in the Raman spectra. The proposed procedure can serve as a tool for proving or disproving infringement of IPR (Intellectual Property Rights) protected preparation methods of ceria-based mixed metal oxide materials.

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