Synthesis of M­­­­­­₁₋₃ₓAl₂O₄:Eu²⁺ₓ/Dy³⁺₂ₓ (M²⁺= Sr²⁺, Ca²⁺ and Ba²⁺) phosphors with long-lasting phosphorescence properties via co-precipitation method

Abstract

The long afterglow fluorescent material of M_1-3xAl₂O₄:Eu²⁺_x/Dy³⁺_2x (M²⁺ = Sr²⁺, Ca²⁺ and Ba²⁺) phosphors are successfully synthesized by calcining precursor obtained via co-precipitation method at 1300 ^oC for 4 h with reducing atmosphere (20% H₂ and 80% N₂. The phase evolution, morphology and afterglow fluorescent properties are systematically studied by the various instruments of XRD, FE-SEM, PLE/PL spectroscopy and fluorescence decay analysis. The PL spectra shows that the Sr_1-3xAl₂O₄:Eu²⁺_x/Dy³⁺_2x phosphors display vivid green emission at ~519 nm (4f⁶5d¹→4f⁷ transition of Eu²⁺) with monitoring of the maximum excitation wavelength at ~334 nm (⁸S_7/2→⁶I_J transition of Eu²⁺), among which the optimal concentration of Eu²⁺ and Dy³⁺ is 15 at % and 30 at %, respectively. The color coordinates and temperature of Sr_1-3xAl₂O₄:Eu²⁺_x/Dy³⁺_2x phosphors are approximately at (~0.27, ~0.57) and ~6700 K, respectively. On the above basis, the M_0.55Al₂O₄:Eu²⁺_0.15/Dy³⁺_0.3 (M²⁺ = Ca²⁺ and Ba²⁺) phosphors is obtained by the same method. The PL spectra of these phosphors shows the strongest blue emission at ~440 nm and cyan emission at ~499 nm under ~334 nm wavelength excitation, respectively, which are blue shifted comparing to Sr_1-3xAl₂O₄:Eu²⁺_x/Dy³⁺_2x phosphors. The color coordinates and temperatures of M_0.55Al₂O₄:Eu²⁺_0.15/Dy³⁺_0.3 (M²⁺ = Ca²⁺ and Ba²⁺) phosphors are approximately at (~0.18, ~0.09)，~2000 K and (~0.18, ~0.42), ~11600 K, respectively. In this work, long afterglow materials of green, blue and cyan aluminates phosphors with excellent properties have been prepared, in order to obtain wide application in the field of night automatic lighting and display.