Facile Synthesis and Luminescence Properties of Y₂O₃:Ln³⁺ (Ln³⁺ = Eu³⁺, Tb³⁺, Dy³⁺, Sm³⁺, Er³⁺, Ho³⁺, Tm³⁺, Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺, Yb³⁺/Ho³⁺) Microspheres

Multicolor and monodisperse Y₂O₃:Ln³⁺ (Ln³⁺ = Eu³⁺, Tb³⁺, Dy³⁺, Sm³⁺, Er³⁺, Ho³⁺, Tm³⁺, Yb³⁺/Er³⁺, Yb³⁺/Ho³⁺) microspheres were prepared through a facile urea-assisted homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrum (EDS), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the samples. The XRD results reveal that the as-prepared spheres can be well indexed to cubic Y₂O₃ phase with high purity. The SEM and TEM images show the obtained Y₂O₃:Ln³⁺ samples consist of regular nanospheres with the mean diameter of 350 nm. And the possible formation mechanism is also proposed. Upon ultraviolet and low-voltage electron beams excitation, Y₂O₃:Ln³⁺ (Ln³⁺ = Eu³⁺, Tb³⁺, Dy³⁺, Sm³⁺, Er³⁺, Ho³⁺, Tm³⁺) samples exhibit respective bright red (Eu³⁺, ⁵D₀→⁷F₂), green (Tb³⁺, ⁵D₄→⁷F₅), blue (Dy³⁺, ⁴F_9/2→⁶H_13/2), yellow (Sm³⁺, ⁴G_5/2→⁶H_7/2), green (Er³⁺, ⁴S_3/2→⁴I_15/2), green (Ho³⁺, ⁵S₂→⁵I₈), blue (Tm³⁺, ¹D₂→³F₄) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Y₂O₃:Ln³⁺ (Ln³⁺ = Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺ and Yb³⁺/Ho³⁺) exhibit characteristic up-conversion (UC) emissions of green (Er³⁺, ²H_11/2, ⁴S_3/2, ²H_11/2→⁴I_15/2), blue (Tm³⁺, ¹G₄→³H₆) and green (Ho³⁺, ⁵F₄, ⁵S₂→ ⁵I₈), respectively. These merits of multicolor emissions in the visible region endow this kind of material with potential applications in the field of light display systems, lasers, and optoelectronic devices.