A new color-adjustable self-emitting in SrGa2Ge2O8 substituted by Eu3+, energy transfer and the determination of luminescence center

Abstract

To explore a new color-adjustable self-emitting in SrGa2Ge2O8:Eu phosphors, a series of experiments and characterization were carried out in this paper. Through a classic solid state method, we successfully synthesized the SrGa2-yGe2-zO8:xEu (0 ≤ x, y, z ≦ 0.2) phosphors. The resulting SrGa2-yGe2-zO8:xEu (0 ≤ x, y, z ≦ 0.2) phosphors had been structurally characterized by X-ray Powder Diffraction Refinements (XRD) and Energy Disperse Spectrometer (EDS). In the present study, it was found that under the excitation of 277 nm, by changing the concentration of doped europium ions, a series of color changes from cyan to white are obtained in SrGa2Ge2O8. The energy transfer from the host to the Eu ions occurs. And the energy transfer ability from the host to Eu3+ were shown to be induced when aluminum was substituted to the nominal composition. The bond energy calculation result shows that the doped Sr2+, Ga3+, Ge4+ ions are substituted by Eu3+, Al3+ and Si4+, respectively, which is consistent with the XRD Rietveld refinement analysis. Also, the EDS analysis shows that atomic ratio is 10:19:20 for Sr/Ga/Ge in SrGa2Ge2O8, which is consistent with the XRD result. Diffuse reflection (DR) spectra and electronic structure display the energy band gap is 4.49 and 3.487eV, respectively. Excited by the 260 nm light, it presents a broad band peaks from 350 to 650 nm with the peak at 441 nm. When Al3+/Si4+ ions are doped in it, the red-shift of the matrix and the photoluminescence improvement of SrGa2Ge2O8: Eu can be found.