Preparation, growth mechanism, size manipulation and near-infrared luminescence enhancement of β-NaYF4:Nd3+ microcrystals via Ca2+ doping

Abstract

β-NaYF₄:Nd³⁺ microcrystals have been prepared successfully by a facile hydrothermal route and characterized through structure analysis, photoluminescence spectroscopy and decay time. Their growth mechanism was profoundly discussed on the basis of different reaction time-dependent morphologies and phase evolution. More importantly, the near-infrared luminescence intensity at 1.06 μm was enhanced by about 3 times via doping Ca²⁺ into the NaYF₄:Nd³⁺ microcrystal lattice. Meanwhile, the morphology and size of as-synthesized microcrystals were also manipulated by the Ca²⁺ doping strategy. The potent mechanism involving improvement of crystallinity along with the modification of the crystal field due to the introduction of Ca²⁺ ions was proposed to understand the enhanced near-infrared emission intensity of the β-NaYF₄:Nd³⁺ microcrystals. The Ca²⁺-doped β-NaYF₄:Nd³⁺ crystals with high performance have potential application in optical communication, laser application and biological deep-tissue imaging.