Photoluminescence of Eu-doped ZnAl-LDH depending on phase transitions caused by annealing temperatures

An Eu-doped ZnAl-layered double hydroxide (ZnAl-LDH) was synthesized by the coprecipitation method at room temperature. A set of as-prepared samples were subjected to annealing at various temperatures from 100, 200, 300, 500, 600, 700, to 800 °C for 1 h, respectively. The annealed samples were characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscope (SEM), and photoluminescence (PL). New phases occurred with annealing temperatures above 300 °C. Meanwhile, the emissions of Eu3+ ions described by 5D0–7FJ transition (J=1, 2, 3, 4), especially for the 5D0–7FJ transition (J=1, 2), varied with phase transitions of its local host materials from ZnAl-LDH, ZnO, to mixed phases of ZnO and ZnAl2O4. The emissions of Eu3+ ions depending on its host materials were discussed.