Formation of Ba3Nb0.75Mn2.25O9-6H During Thermochemical Reduction of Ba4NbMn3O12-12R

Nicholas Strange, Robert Bell, James Park, Kevin Stone, Eric Coker, David Ginley

Research output: Contribution to journalArticlepeer-review

1 Scopus Citations

Abstract

The resurgence of interest in hydrogen-related technologies has stimulated new studies aimed at advancing lesser-developed water-splitting processes, such as solar thermochemical hydrogen production (STCH). Progress in STCH has been largely hindered by a lack of new materials able to efficiently split water at a rate comparable to ceria under identical experimental conditions. BaCe0.25Mn0.75O3 (BCM) recently demonstrated enhanced hydrogen production over ceria and has the potential to further our understanding of two-step thermochemical cycles. A significant feature of the 12R hexagonal perovskite structure of BCM is the tendency to, in part, form a 6H polytype at high temperatures and reducing environments (i.e., during the first step of the thermochemical cycle), which may serve to mitigate degradation of the complex oxide. An analogous compound, namely BaNb0.25Mn0.75O3 (BNM) with a 12R structure was synthesized and displays nearly complete conversion to the 6H structure under identical reaction conditions as BCM. The structure of the BNM-6H polytype was determined from Rietveld refinement of synchrotron powder X-ray diffraction data and is presented within the context of the previously established BCM-6H structure.

Original languageAmerican English
Pages (from-to)469-473
Number of pages5
JournalActa Crystallographica Section E: Crystallographic Communications
Volume79
Issue numberPart 5
DOIs
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 International Union of Crystallography. All rights reserved.

NREL Publication Number

  • NREL/JA-5900-86177

Keywords

  • complex oxides
  • crystal structure
  • hexagonal perovskites
  • powder synchrotron diffraction
  • solar thermochemical hydrogen production

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