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Hydroxyl Defects and Oxide Vacancies within Ringwoodite-toward Understanding the Defect Chemistry of Spinel-Type Oxides

Title data

Grüninger, Helen ; Liu, Zhaodong ; Brauckmann, J. Ole ; Fei, Hongzhan ; Boffa Ballaran, Tiziana ; Martin, Thomas ; Siegel, Renée ; Kentgens, Arno P. M. ; Frost, Daniel J. ; Senker, Jürgen:
Hydroxyl Defects and Oxide Vacancies within Ringwoodite-toward Understanding the Defect Chemistry of Spinel-Type Oxides.
In: Journal of Physical Chemistry C. Vol. 124 (June 2020) Issue 22 . - pp. 12001-12009.
ISSN 1932-7447
DOI: https://doi.org/10.1021/acs.jpcc.0c03016

Abstract in another language

The high-pressure mineral ringwoodite (gamma-Mg2SiO4) is a major component of the Earth's mantle and is able to incorporate large amounts of water in the form of hydroxyl defects. Understanding its underlying defect chemistry does not only have implications for geological transport processes, but will also allow for extending this knowledge to defect mechanisms within spinel-type oxide materials in general, which are commonly used for heterogeneous catalysts, battery electrodes, and ionic conductors. Here, we present a comprehensive study combining X-ray diffraction, electron-microprobe analysis, Fourier-transform infrared, and H-1 MAS NMR spectroscopy on a suit of nanoliter crystals with water contents between 0.05 and 2 wt %. We observed that both oxide vacancies and hydroxyl defects are formed and stabilized by Mg and Si vacancies. The latter are the main sources for the water uptake at very low and large water contents, while Mg vacancies dominate the moderate region in between. Intriguingly, the Si defects originate from the inherent Mg/Si cation inversion, typical to spinel-type materials at higher temperatures. By demonstrating that MAS NMR spectroscopy on nanoliter crystals is feasible, we additionally offer a promising avenue for analyzing synthetically challenging materials in the future.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: ISI:000538758700030
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry III
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry III > Chair Inorganic Chemistry III - Univ.-Prof. Dr. Jürgen Senker
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Experimental Geosciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Experimental Geosciences > Chair Experimental Geosciences - Univ.-Prof. Dr. Daniel Frost
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 04 Aug 2020 10:16
Last Modified: 04 Aug 2020 10:16
URI: https://eref.uni-bayreuth.de/id/eprint/56303