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Appl. Sci. 2017, 7(12), 1243; https://doi.org/10.3390/app7121243

Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanoclay Materials

1
Department of Chemistry, University of Turku, FI-20014 Turku, Finland
2
Doctoral Programme in Physical and Chemical Sciences, University of Turku Graduate School (UTUGS), FI-20014 Turku, Finland
3
Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
4
Department of Applied Physics, Institute of Physics, University of São Paulo, São Paulo BR-05508090, Brazil
5
Turku University Centre for Materials and Surfaces (MatSurf), FI-20014 Turku, Finland
6
Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo BR-05508000, Brazil
7
Department of Physics, University of the Free State, Bloemfontein ZA-9300, South Africa
*
Author to whom correspondence should be addressed.
Received: 1 November 2017 / Revised: 24 November 2017 / Accepted: 27 November 2017 / Published: 30 November 2017
(This article belongs to the Section Chemistry)
Full-Text   |   PDF [4045 KB, uploaded 30 November 2017]   |  

Abstract

The smectites represent a versatile class of clay minerals with broad usage in industrial applications, e.g., cosmetics, drug delivery, bioimaging, etc. Synthetic hectorite Na0.7(Mg5.5Li0.3)[Si8O20](OH)4 is a distinct material from this class due to its low-cost production method that allows to design its structure to match better the applications. In the current work, we have synthesized for the first time ever nanoclay materials based on the hectorite structure but with the hydroxyl groups (OH) replaced by Br or I, yielding bromohectorite (Br-Hec) and iodohectorite (I-Hec). It was aimed that these materials would be used as phosphors. Thus, OH replacement was done to avoid luminescence quenching by multiphonon de-excitation. The crystal structure is similar to nanocrystalline fluorohectorite, having the d001 spacing of 14.30 Å and 3 nm crystallite size along the 00l direction. The synthetic materials studied here show strong potential to act as host lattices for optically active species, possessing mesoporous structure with high specific surface area (385 and 363 m2 g−1 for Br-Hec and I-Hec, respectively) and good thermal stability up to 800 °C. Both materials also present strong blue-green emission under UV radiation and short persistent luminescence (ca. 5 s). The luminescence features are attributed to Ti3+/TiIV impurities acting as the emitting center in these materials. View Full-Text
Keywords: bromohectorite; iodohectorite; clay materials; host lattice; titanium luminescence bromohectorite; iodohectorite; clay materials; host lattice; titanium luminescence
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Santos, H.S.; Norrbo, I.; Laihinen, T.; Sinkkonen, J.; Mäkilä, E.; Carvalho, J.M.; Damlin, P.; Brito, H.F.; Hölsä, J.; Lastusaari, M. Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanoclay Materials. Appl. Sci. 2017, 7, 1243.

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