Y₂O₃:Eu³⁺ Nanophosphor-Coated Mica or TiO₂/Mica as Red-Emitting Pearl Pigment: Coating Factors, Luminescent and Gloss Properties

Abstract

Red-emitted Y2O3:Eu3+ nanophosphor coated on a mica flake (Y2O3:Eu@MF) or on TiO2 having a rutile crystalline mica flake (Y2O3:Eu@TMF) has been prepared by an electrostatic interaction with the wet-coating method for the purpose of a pigment with luminescent and gloss properties. Aggregated Y2O3:Eu3+, prepared by the template method, was dispersed into nanosol by a controlled bead-mill wet process. The (+) charged Y2O3:Eu3+ nanosol was effectively coated on the (−) charged mica flake (MF) or the TiO2/mica flake (TMF) by an electrostatic interaction between the Y2O3:Eu3+ nanoparticles and MF or TMF at pH 6–8. The coating factors of Y2O3:Eu@MF were also studied and optimized by controlling the pH, stirring temperature, calcination temperature, and coating amount of Y2O3:Eu3+. The Y2O3:Eu3+ was partially coated and optimized on the MF or TMF surface with a coating coverage of about 40–50% or 60–70%, respectively. Y2O3:Eu@MF and Y2O3:Eu@TMF were exhibiting the luminescent property of a red color under a 254 nm wavelength, and had a color purity of over 95% according to CIE chromaticity coordinates. These materials were characterized by X-ray diffraction, FE-SEM, zeta potential, and a fluorescence spectrometer. These materials with luminescent and gloss properties prepared in this work potentially meet their applications for security purposes.

Keywords

• red-emitted nanophosphor
• Y₂O₃:Eu³⁺-coated mica or TiO₂/mica
• luminescence
• gloss
• pearl pigment