Self-Assembled 3D Urchin-Like NaY(MoO4)2:EU3+/Tb3+ Microarchitectures: Hydrothermal Synthesis and Tunable Emission Colors

Novel 3D urchin-like NaY(MoO4)(2) microarchitectures have been successfully synthesized by a complexing-agent-assisted hydrothermal process followed by a subsequent heat treatment process. The shape and size of the double alkaline rare earth molybdates precursor microstructures can be tuned effectively by controlling the reaction conditions, such as reaction time, the amount of organic additive trisodium citrate (Cit(3-)), and the kinds of organic additives. The possible formation mechanism for urchin-like microarchitectures has been presented. It is found that the Cit(3-) organic molecule, acting as the chelating agent and shape modifier, plays a key role in fine-tuning the precursor microstructures. The as-formed precursor could transform into NaY(MoO4)(2) with their original urchin-like morphology and slight shrinkage in the size after postannealing process. Under UV and low-voltage electron beam excitation, 5 mol % Eu3+ and 5 mol % Tb3+ doped NaY(MoO4)(2) samples exhibit strong red and green emission, corresponding to the characteristic lines of Eu3+ and Tb3+, respectively. Moreover, the luminescence colors of the Eu3+ and Tb3+ codoped NaY(MoO4)(2) samples can be tuned from red, yellow, and green-yellow to green by simply adjusting the relative doping concentrations of the activator ions under a single wavelength excitation, which might find potential applications in the fields such as light display systems and optoelectronic devices.