ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Luminescent Eu-doped GdVO₄ nanocrystals as optical markers for anti-counterfeiting purposes

Elisa Moretti, Giorgia Pizzol, Marina Fantin, Francesco Enrichi, Paolo Scopece, Manuel Ocaña, and Stefano Polizzi

Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, INSTM Venice Research Unit, Mestre Venice, Italy

E-mail: elisa.moretti@unive.it

Abstract: Luminescent Eu:GdVO₄ nanoparticles, with an average size of 60 nm, were deposited first on monocrystalline silicon wafers, then on four different natural stone materials, by a spray-coating technique and a silica layer was subsequently deposited by atmospheric pressure plasma jet to protect the luminescent layer and improve its adhesion to the substrate. The luminescent films were characterized by photoluminescence excitation and emission, while the surface morphology was examined by FEG-SEM microscopy and spectroscopic ellipsometry to determine the coating thickness. The optical appearance of the coatings was also evaluated by colorimetric measurements and the efficacy of the fixing action of the silica layer was estimated by PL measurements performed before and after a Scotch™ tape peeling test. The proposed methodology, easily applied on the surface of stone supports, has led to the realization of a luminescent film displaying good mechanical properties, transparent and undetectable in the presence of visible light, but easily activated by UV light source, indicating that the Eu:GdVO₄ nanophosphors could be used as luminescent nanotags for a reliable anti-counterfeiting technology.

Keywords: Eu-doped nanophosphors; Optical identification markers; Spray deposition; Atmospheric pressure plasma jet

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-016-0081-8

Chemical Papers 71 (1) 149–159 (2017)