A new blue long-lasting phosphorescence phosphor Mg₂SnO₄:Bi³⁺: synthesis and luminescence properties

In this article, we synthesized a new long-lasting phosphor Mg₂SnO₄:Bi³⁺ by traditional high-temperature solid-state reaction method. The structure and luminescence properties were characterized using X-ray powder diffraction, photoluminescence spectra, phosphorescence spectra, decay curves and thermoluminescence curves. The results show that the phosphor can exhibit blue emission corresponding to ³P₁–¹S₀ transition of Bi³⁺ under UV light excitation. After ceasing the excitation, blue phosphorescence can be observed. For the optimal phosphor its blue phosphorescence could be observed by human naked eyes in the dark even after 3 h. The thermoluminescence analysis reveals that three kinds of trapping centers exist in the phosphor, of which the ones at 329 and 359 K are responsible for the long-lasting phosphorescence at room temperature. Bi³⁺ ions took the sites of Mg²⁺ and Sn⁴⁺ forming three different types of emitting centers, and yielding charged impurity defects which acted as charge trap centers and partly stored the excitation energy.