Luminescence and microstructure of Sr₂Mg(BO₃)₂ doped with Eu

Sr₂Mg(BO₃)₂ doped with Eu was synthesized respectively in air and weak reducing atmosphere (combustion of carbon particle), whose photoluminescence characteristics and structure were also studied at room-temperature. In air, the fluorescent body's color was white for different synthesized temperatures. At room temperature, the sample was excited and showed red typical emission spectrum of Eu³⁺ whose emission apex were sharp near 612 nm and emission spectrum was made up of the charge transformation band (CTB) of Eu³⁺ and excitation spectrum of 4f→4f high energy level transition, then reached the area of VUV. However, under reducing atmosphere (combustion of carbon particles), the color of the sample yielded was yellow, whose color became deeper with increasing temperature and showed phase transition. Using UV excitation, the luminescence of yellow sample was very weak. In a complicated broad spectrum at visible light area, the red emission spectrum of Eu²⁺ was not observed. Crystal structure and luminescence of the sample were completely different from the results of Diaz and Keszler. Two samples were prepared under oxidation and reducing atmosphere at high temperature, which were different on crystal structure and microstructure. By studying Sr₂Mg(BO₃)₂:Eu³⁺ a series of directional faults or educts were found, because Eu³⁺ ions substituted for Sr²⁺ ions. However, microstructure of Sr₂Mg (BO₃)₂:Eu²⁺ is more complicated, whose excitation spectrum might be excited by Eu²⁺. By XRD pattern of the samples, phase transition could be found. Twins and clusters that were formed from point defect such as interstitial atom and big angle crystal boundary could be found by TEM.