RT journal article
T1 Determining the Role of Fe-Doping on Promoting the Thermochemical Energy Storage Performance of (Mn1-xFex)(3)O-4 Spinels
A1 Carrillo, Alfonso J.
A1 Chinchilla Reyes, Lidia Esther
A1 Iglesias Juez, Ana
A1 Gutiérrez Rubio, Santiago
A1 Sastre, Daniel
A1 Pizarro, Patricia
A1 Hungría Hernández, Ana Belén
A1 Coronado, Juan M.
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
K1 high-resolution STE
K1 Min situ XAS
K1 manganese oxides
K1 redox
K1 thermochemical heat storage
AB 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.
PB WILEY
SN 2366-9608
YR 2021
FD 2021-09
LK http://hdl.handle.net/10498/25801
UL http://hdl.handle.net/10498/25801
LA eng
NO 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.
DS Repositorio Institucional de la Universidad de Cádiz
RD 08-nov-2026