Journal Article

FZJ-2016-04563

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate

Ojwang, D. O. ; Grins, J. ; Wardecki, D. ; Valvo, M. ; Renman, V. ; Häggström, L. ; Ericsson, T. ; Gustafsson, T. ; Mahmoud, A. ; Svensson, G. (Corresponding author) ; Hermann, R.FZJ*

2016
American Chemical Society Washington, DC

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Please use a persistent id in citations: doi:10.1021/acs.inorgchem.6b00227

Abstract: Copper hexacyanoferrate, CuII[FeIII(CN)6]2/3·nH2O, was synthesized, and varied amounts of K+ ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as CuII[FeIII(CN)6]2/3·nH2O + 2x/3K+ + 2x/3e– ↔ K2x/3CuII[FeIIxFeIII1–x(CN)6]2/3·nH2O. Infrared, Raman, and Mössbauer spectroscopy studies show that FeIII is continuously reduced to FeII with increasing x, accompanied by a decrease of the a-axis of the cubic Fm3̅m unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction, ∼20% of the FeIII, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of ∼26 wt % upon heating to 180 °C, above which the structure starts to decompose. The crystal structures of CuII[FeIII(CN)6]2/3·nH2O and K2/3Cu[Fe(CN)6]2/3·nH2O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)6 groups are vacant, and the octahedron around CuII is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the −Cu–N–C–Fe– framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.

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Contributing Institute(s):

1. Streumethoden (JCNS-2)
2. Streumethoden (PGI-4)
3. JARA-FIT (JARA-FIT)

Research Program(s):

1. 144 - Controlling Collective States (POF3-144) (POF3-144)
2. 524 - Controlling Collective States (POF3-524) (POF3-524)
3. 6212 - Quantum Condensed Matter: Magnetism, Superconductivity (POF3-621) (POF3-621)
4. 6213 - Materials and Processes for Energy and Transport Technologies (POF3-621) (POF3-621)
5. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Appears in the scientific report 2016

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; Nationallizenz ; No Authors Fulltext ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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