Energy transfer of wide band long persistent phosphors of Sm3+-Doped ZrSiO4

The long persistent phosphors Zr(1-x)SiO4:Sm3+x were synthesized via solid-state reaction in a reducing atmosphere. The X-ray powder diffractometer (XRD) was utilized to analyze the structure of ZrSiO4:Sm3+. The electron cloud density and their shifts around the ions were explored by the X-ray photoelectron spectrometry (XPS). The luminescence properties and possible mechanism of the long persistent phosphors were studied by excitation and emission spectra, decay curves and TL curves of the samples. The observed main emission peaking at 466 nm was attributed to the d-d transition of Zr4+ and several other emission peaks were contributed by the Sm3+ transitions of 6H5/2-4G5/2 (567 nm), 6H7/2-4G5/2 (603 and 615 nm) and 6H9/2-4G5/2 (650 and 660 nm). ZrSiO4:Sm3+ exhibited a turquoise persistent luminescence after UV excitation and a pale red light under the exposure of 365 nm UV. Many means of analysis were used to explore the mechanism of which several factors were responsible for the improvement of luminescence properties.