Mössbauer Spectroscopic Investigation of FeII and FeIII 3,4,5‐Trihydroxybenzoates (Gallates) – Proposed Model Compounds for Iron‐Gall Inks |
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| Authors: | Friedrich E Wagner Anton Lerf |
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| Affiliation: | 1. Physics Department, Technical University of Munich, 85748 Garching, Germany;2. Walther‐Mei?ner‐Instiut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany |
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| Abstract: | Iron gallates with iron in the oxidation states Fe2+ and Fe3+ were prepared and studied by Mössbauer spectroscopy, X‐ray diffraction, and IR spectroscopy. FeIII 3,4,5‐trihydroxybenzoate (gallate) Fe(C7O5H4) · 2H2O, whose structure was first determined by Wunderlich, was obtained by the reaction of gallic acid and metallic iron or by oxidation of the FeII gallate, which was obtained by the reaction of ferrous sulfate with 3,4,5‐trihydroxybezoic acid (gallic acid) under anoxic conditions. Trials to reproduce the hydrothermal preparation method of Feller and Cheetham show that the result depends crucially on the free gas volume in the reaction vessel. If there is no free volume one obtains the same FeIII gallate as in the other preparation methods. With a large free volume another compound was found to form whose composition and structure could not be determined. It could be specified only by Mössbauer spectroscopy. FeIII gallate, the FeII gallate, and the new phase show magnetic ordering at liquid helium temperature. |
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| Keywords: | Mö ssbauer spectroscopy X‐ray diffraction Attenuated total reflectance (ATR) Fourier transform infrared spectrum Iron Gallates |
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