Magnetic-field tunability of optical properties in colloidal suspensions of goethite (α-FeOOH) nanorods

Year: 2019

Authors: Sani E., Mercatelli L., Martina M.R., Barison S, Agresti F.

Autors Affiliation: National Institute of Optics (INO), National Research Council of Italy (CNR), Largo E. Fermi, 6, 50125, Firenze, Italy;
Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), National Research Council of Italy (CNR), Corso Stati Uniti 4, 35127, Padova, Italy

Abstract: The dependence of polarized optical properties of colloidal suspensions of goethite (α-FeOOH) nanorods in water and PAO base fluids under the action of an applied magnetic field are investigated in the ultraviolet, visible and near infrared from 300 to 1500 nm wavelength. We found that the transmittance in the NIR range can be tuned by changing magnetic field direction and strength. Moreover, we found that the magnetic field dependence of optical properties is strongly connected to the base fluid where magnetic nanoparticles are suspended. The obtained results show that the optical properties of goethite-based suspensions are very sensitive to even weak external magnetic fields, with promising perspectives for sensing applications.

Journal/Review: OPTICAL MATERIALS

Volume: 96      Pages from: 109303-1  to: 109303-7

More Information: Highlights: o Stable suspension of goethite (?-FeOOH) nanorods are prepared in both water and PAO. o Spectral optical properties are studied as a function of strength and direction of the external magnetic field. o The magnetic field orients the nanorods and changes their polarized transmittance spectrum. o Both birefringence and optical activity are affected. o Goethite colloids are very sensitive to even weak magnetic fields.
KeyWords: Goethite
NIR absorption tuneability
Optical properties
Optical extinction coefficient
DOI: 10.1016/j.optmat.2019.109303

Citations: 3
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