Study on a Novel Binary Zn _n Eu Layered Double Hydroxide with Excellent Fluorescence

A group of binary Zn_nEu-LDHs with Zn²⁺/Eu³⁺ molar ratios of 5.0, 6.0, 7.0, and 8.0 have been obtained in ammonia water media by hydrothermal treatment. The structure, composition, and fluorescent property of samples have been investigated using various techniques. Compositional analyses revealed that the composition of samples was in agreement with that of the initial reactants. X-ray diffraction (XRD) suggested that the Zn_nEu-LDHs exhibited typical layered structure with orthorhombic symmetry. All the Zn_nEu-LDHs appeared strong red emissions attributed to ⁵D₀ → ⁷F _J (J = 1, 2) transitions of Eu³⁺. Moreover, the intensity of emissions due to ⁵D₀ → ⁷F_J (J = 1, 2) transitions of Eu³⁺ tended to increase with the Zn²⁺/Eu³⁺ molar ratio varied from 8.0, 7.0 to 6.0, then decreased as the Zn²⁺/Eu³⁺ molar ratio reduced to 5.0. The strongest fluorescence was found to be at Zn²⁺/Eu³⁺ molar ratio of 6.0. Further the fluorescence decay spectra show that the Zn _n Eu-LDH have similar behavior of fluorescent decay and decayed more slowly than that of the Eu(OH)₃. These results indicate that the novel binary Zn_nEu-LDHs have better fluorescent property and may be potential application as fluorescent materials.