Synthesis and enhanced luminescence of Eu3+-doped Mg2SnO4 nanophosphor

Undoped and Eu3+-doped Mg2SnO4(or MTO) nanophosphors were prepared by the sol-gel auto-combustion method. The X-ray diffraction (XRD) analysis confirmed that both samples showed cubic inverse spinel Mg2SnO4 structure. From microstructural analysis, undoped MTO showed a uniform spherical-like morphology, with an average grain size of 50–60 nm whereas Eu-doped MTO showed larger grains with irregular and elongated rod-shaped morphology. Photoluminescence (PL) spectra identified broad and intense emission bands centered at 419–529 nm associated with the intrinsic defects of the host and an orange band centered at 592 nm assigned to the Eu3+ cation. Eu3+-doped MTO also exhibited high value of quantum efficiency and prolonged lifetime. From the cathodoluminescence analysis, intense and sharp emission bands ranges from blue to red spectral regions were exhibited. The dominant red emission band at 622 nm is attributed to the electric dipole transition 5D0 →7F2, indicating that the Eu3+ ions locate at the site of non-inversion symmetry. The formation of defects and vacancies due to the doping of Eu3+ ions into MTO phosphor results in the enhancement of afterglow and photostimulated luminescence.