@misc{10498/25801,
year = {2021},
month = {9},
url = {http://hdl.handle.net/10498/25801},
abstract = {Mn oxides are promising materials for thermochemical heat store, but slow reoxidation of Mn3O4 to Mn2O3 limits efficiency. In contrast, (Mn1-xFex)(3)O-4 oxides show an enhanced transformation rate, but fundamental understanding of the role played by Fe cations is lacking. Here, nanoscale characterization of Fe-doped Mn oxides is performed to elucidate how Fe incorporation influences solid-state transformations. X-ray diffraction reveals the presence of two distinct spinel phases, cubic jacobsite and tetragonal hausmannite for samples with more than 10% of Fe. Chemical mapping exposes wide variation of Fe content between grains, but an even distribution within crystallites. Due to the similarities of spinels structures, high-resolution scanning transmission electron microscopy cannot discriminate unambiguously between them, but Fe-enriched crystallites likely correspond to jacobsite. In situ X-ray absorption spectroscopy confirms that increasing Fe content up to 20% boosts the reoxidation rate, leading to the transformation of Mn2+ in the spinel phase to Mn3+ in bixbyite. Extended X-ray absorption fine structure shows that Fe-O length is larger than Mn-O, but both electron energy loss spectroscopy and X-ray absorption near edge structure indicate that iron is always present as Fe3+ in octahedral sites. These structural modifications may facilitate ionic diffusion during bixbyite formation.},
organization = {The authors thank the financial support from "Ramon Areces" Foundation (project SOLARKITE), Comunidad de Madrid and European Structural Funds (project ACES2030 P2018/EMT-4319), and University of Cadiz and European Structural Funds (project FEDER-UCA18-107139). A.J.C. thanks the financial support by Juan de la Cierva Formacion Program (MICINN), grant FJCI-2017-33967. The authors acknowledge ALBA-CELLS Synchrotron facility for granting beamtime at CLAESS (experiment 2016021666-2) and Electron Microscopy division located in the Servicios Centrales de Investigacion Cientifica y Tecnologica (SC-ICYT) of the University of Cadiz. Assistance of Dr. Laura Simonelli during the XAS measurements in ALBA is fully appreciated.},
publisher = {WILEY},
keywords = {high-resolution STE},
keywords = {Min situ XAS},
keywords = {manganese oxides},
keywords = {redox},
keywords = {thermochemical heat storage},
title = {Determining the Role of Fe-Doping on Promoting the Thermochemical Energy Storage Performance of (Mn1-xFex)(3)O-4 Spinels},
doi = {10.1002/smtd.202100550},
author = {Carrillo, Alfonso J. and Chinchilla Reyes, Lidia Esther and Iglesias Juez, Ana and Gutiérrez Rubio, Santiago and Sastre, Daniel and Pizarro, Patricia and Hungría Hernández, Ana Belén and Coronado, Juan M.},
}