Synthesis of cubic and hexagonal ordered mesoporous YVO4:Eu3+ and their photoluminescence properties

Abstract

Cubic and hexagonal ordered mesoporous Eu³⁺-doped yttrium vanadate (YVO₄:Eu³⁺) have been synthesized successfully through the nanocasting route with a Y(NO₃)₃/Eu(NO₃)₃/NH₄VO₃/HNO₃/ethanol system as a guest unit and KIT-6 or SBA-15 silica as the hard template host, and were characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and low-temperature nitrogen adsorption. The prepared YVO₄:Eu³⁺ samples have the characteristic cubic (Ia3d) (or hexagonal (p6mm)) ordered mesostructure based on different hard templates, and possess high surface area, large pore volume and uniform pore size distribution. Photoluminescence (PL) measurement shows that the main red emission peaks of two mesoporous YVO₄:Eu³⁺ samples appear at 618 nm, and different mesostructures lead to different optimum concentrations of Eu³⁺ dopant and different PL intensities. For the hexagonal mesoporous YVO₄:Eu³⁺, when Eu³⁺ dopant is 5(mol)% the highest PL intensity can be reached; for the cubic one, optimized Eu³⁺ amount is 8 mol%. The interaction between Eu³⁺ ions in hexagonal (p6mm) mesoporous YVO₄:Eu³⁺ is more active than that in cubic (Ia3d) mesoporous YVO₄:Eu³⁺, thus the absorbed energy is dissipated by nonradiation; while the cubic mesoporous YVO₄:Eu³⁺ has more Eu³⁺ luminescent sites, compared with the hexagonal mesostructure one.