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Tailoring the size, inversion parameter, and absorption of phase-pure magnetic MgFe2O4 nanoparticles for photocatalytic degradations

DOI: 10.1021/acsanm.0c02705 DOI Help

Authors: Andre Bloesser (University of Bayreuth) , Hannah Kurz (University of Bayreuth) , Jana Timm (University of Bayreuth) , Florian Wittkamp (Ruhr-Universitaẗ Bochum) , Christopher Simon (University of Bayreuth) , Shusaku Hayama (Diamond Light Source) , Birgit Weber (University of Bayreuth) , Ulf-Peter Apfel (Ruhr-Universitaẗ Bochum) , Roland Marschall (University of Bayreuth)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Applied Nano Materials

State: Published (Approved)
Published: October 2020
Diamond Proposal Number(s): 23538

Abstract: Phase-pure magnesium ferrite (MgFe2O4) spinel nanocrystals are synthesized by a fast microwave-assisted route. The elemental composition is optimized via the ratio of the precursor mixture and controlled by energy-dispersive X-ray spectroscopy. Fine-tuning of the magnetic properties without changing the overall elemental composition is demonstrated by superconducting quantum interference device (SQUID) magnetometry and Mössbauer spectroscopy. Together with X-ray absorption spectroscopy and X-ray emission spectroscopy, we confirm that the degree of cation inversion is altered by thermal annealing. We can correlate the magnetic properties with both the nanosize influence and the degree of inversion. The resulting nonlinear course of saturation magnetization (Ms) in correlation with the particle diameter allows to decouple crystallite size and saturation magnetization, by this providing a parameter for the production of very small nanoparticles with high Ms with great potential for magnetic applications like ferrofluids or targeted drug delivery. Our results also suggest that the optical band gap of MgFe2O4 is considerably larger than the fundamental electronic band gap because of the d5 electronic configuration of the iron centers. The presented different electronic transitions contributing to the absorption of visible light are the explanation for the large dissent among the band gaps and band potentials found in the literature.

Journal Keywords: MgFe2O4; magnetic nanoparticles; photocatalysis; photoelectrochemistry; degree of inversion

Diamond Keywords: Photocatalysis

Subject Areas: Materials, Chemistry, Physics

Instruments: I20-Scanning-X-ray spectroscopy (XAS/XES)

Other Facilities: BM20 at ESRF

Added On: 02/11/2020 14:02

Discipline Tags:

Physics Physical Chemistry Catalysis Energy Materials Chemistry Magnetism Materials Science Nanoscience/Nanotechnology

Technical Tags:

Spectroscopy X-ray Emission Spectroscopy (XES)