The Sol–Gel Process Synthesis of GdAl₃(BO₃)₄:Eu³⁺ Nanophosphors

GdAl₃(BO₃)₄:Eu³⁺ red phosphors were prepared using citric acid as complex agent by sol–gel technique. The preparation conditions of the precursor synthesis, including crystallization temperature and crystallization time were investigated. Their structure and luminescence properties were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry. The results showed that GdAl₃(BO₃)₄:Eu³⁺ phosphor crystallized at 960 °C for 2 h have been synthesized by sol–gel method. The phosphor is distributed into hexagonal system and the lattice parameters are a = 9.2992 nm c = 7.2577 nm. The excitation spectrum of Gd_0.95Al₃(BO₃)₄:Eu_0.05 ³⁺ samples is complex and the frequency scale is wide. It consists of a number of main excitation transitions namely ⁸S_7/2 → ⁶I _J (270 nm) of Gd³⁺, and the others ⁷F₀ → ⁵L₆ (400 nm), ⁷F₀ → ⁵D₂ (472 nm) and ⁷F₀ → ⁵D₁ (542 nm) of Eu³⁺. The main emission peaks are 614 nm and 619 nm, which are the characteristic emission peaks of Eu³⁺. These emission peaks correspond to the transition from ⁵D₀ to ⁷F₂ of Eu³⁺. The shape and the wavelength range of the emission spectrum are similar when the sample was excited by different excitation spectrum. Only the relative intensity of the emission peaks is different from each other.