Tunable light emission of amorphous Eu3+/Tb3+ co-doped MgAl-hydroxide salts depending on phase transition

Abstract Two of Eu3 +/Tb3 + co-doped amorphous Mg-Al double hydroxide salts, with Eu3 +/Tb3 + molar ratios of 1/4 and 4/1, were prepared and their photoluminescence dependence on phase transition has been investigated. Our results revealed that the co-doped amorphous samples exhibited excellent green emissions due to 5D4 → 7FJ (J = 5, 6) transitions of Tb3 + under the excitation of 350, 370 and 380 nm, and red emissions due to 5D0 → 7FJ (J = 1, 2) transitions of Eu3 + under the excitation of 395 and 468 nm. Moreover, the emission intensity is dependent on the Eu3 +/Tb3 + molar ratio. When the amorphous Eu3 +/Tb3 + co-doped samples were annealed at 200 and 300 °C, the phase transition was unobservable. After the samples were annealed at 500 °C, the samples began to transform. Further, the multi-crystalline phases formed after the samples were annealed at 700 and 900 °C. Moreover, the emissions attributed to Eu3 + and Tb3 + incorporated in the amorphous host are greatly stronger than that of in the multi-crystalline host. These results indicated the amorphous phase was more favorable for the emissions of Eu3 + and Tb3 + compared with that of the multi-crystalline phases.