NIR transmittance tuneability under a magnetic field of colloidal suspensions of goethite (alpha-FeOOH) nanorods

Year: 2017

Authors: Agresti F., Zin V., Barison S., Sani E., Meucci M., Mercatelli L., Nodari L., Rossi S., Bobbo S., Fabrizio M.

Autors Affiliation: Natl Res Council Italy CNR, Inst Condensed Matter Chem & Technol Energy ICMAT, Corso Stati Uniti 4, I-35127 Padua, Italy; Natl Res Council Italy CNR, Natl Inst Opt INO, Largo E Fermi 6, I-50125 Florence, Italy; Natl Res Council Italy CNR, Inst Construct Technol ITC, Corso Stati Uniti 4, I-35127 Padua, Italy.

Abstract: Goethite (alpha-FeOOH) nanorods have been synthesized using two different methods, by aging at different temperatures of ferrihydrite suspensions obtained through co-precipitation, or by fast conversion of ferrihydrite through ultrasonic irradiation. The synthesis method and parameters influenced the size and shape of nanoparticles. Stable colloidal suspensions of nanorods have been prepared by purification of the precipitates and subsequent dispersion in deionised water by sonication. The synthesized nanopowders have been characterized by Powder X-ray Diffraction and Scanning Electron Microscopy and the colloidal suspensions by Dynamic Light Scattering and zeta-potential measurements. The magnetic field at nuclei level has been investigated by Mossbauer spectroscopy. Moreover, since a colloidal suspension of goethite is a mineral liquid crystal and due to its peculiar magnetic properties, polarized radiation transmittance of colloids in the UV-vis-NIR range has been determined under different magnetic field directions and intensities. It has been found that the transmittance in the NIR range can be tuned by changing magnetic field direction and strength.

Journal/Review: RSC ADVANCES

Volume: 7 (20)      Pages from: 12429  to: 12436

More Information: The authors are grateful to Dr Rosalba Gerbasi (CNR-ICMATE) for XRD measurements. E. S. gratefully acknowledges the Italian bank foundation “Fondazione Ente Cassa di Risparmio di Firenze” for supporting this activity within the framework of “SOLE NANO” project (pratica 2015.0861). Thanks are due to Mr Massimo D´Uva, Mr Mauro Pucci (CNR-INO) and Mr Saverio Priori (IFAC-CNR) for technical assistance.
KeyWords: Deionized water; Infrared devices; Irradiation; Light scattering; Liquid crystals; Magnetic fields; Magnetism; Nanorods; Scanning electron microscopy; Suspensions (fluids); Synthesis (chemical); X ray diffraction, Colloidal suspensions; Different-magnetic fields; Magnetic field direction; Mineral liquid crystals; Powder X ray diffraction; Ssbauer spectroscopies; Ultrasound irradiation; Zeta potential measurements, Suspensions (components)
DOI: 10.1039/c7ra00721c

Citations: 7
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