Microstructure control by Y³⁺ ions doping in CaMoO₄:Eu³⁺: Tunable optical and luminescent performance

Highlights: • The lattice contracted with the increase of the concentration of Y³⁺ co-doped. • A red shift of electronic absorption band of the ¹A₁ → ¹T₁ transition was observed. • Quantum efficiency was enhanced at the appropriate concentration of Y³⁺ co-doped. • Y³⁺ co-doped was favorable to improve the color purity of CaMoO₄:Eu³⁺ crystals. - Abstract: In this paper, Y³⁺ ions doped CaMoO₄:Eu³⁺ with controlled microstructures were prepared via a hydrothermal method. All samples were fully characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–vis diffuse reflectance spectroscopy, and photoluminescence measurement. The luminescent performance improvement aroused by doping was systematically investigated after inducing Y³⁺ as co-doping ions in CaMoO₄:Eu³⁺ lattice. It is found that the lattice of Y³⁺ doped CaMoO₄:Eu³⁺ nanocrystals contracted with increasing the Y³⁺ concentration, resulting in a red shift of ¹A₁ → ¹T₁ transition from the valence band to the conduction band. Meanwhile, excitation band at 300 nm corresponding to the typical ¹A₁ → ¹T₁ transition also shifted to lower energy, originating from the charge-transfer between MoO₄²⁻ group and Eu³⁺ ions. When the Y³⁺ doping concentration was less than 0.05, the quantum efficiency of Y³⁺ doped CaMoO₄:Eu³⁺ nanocrystals was all superior to pure CaMoO₄:Eu³⁺ nanocrystals, which can be assigned to the lattice structure contraction, co-doping effect, doping concentration variation. However, as the content of Y³⁺ ions further increasing, Y³⁺ ion should act as a luminescence killer, and therefore resulting in a nonradiative de-excitation