Fabrication and luminescence properties of Al2O3:Tb3+ microspheres via a microwave solvothermal route

Al2O3:Tb3+ green phosphors were synthesized via a microwave solvothermal and thermal decomposition route, and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra, and decay curves. XRD results indicate that Tb3+ doped samples are γ-Al2O3 after being calcined at 773 K. SEM results show that the particles of Al2O3:Tb3+ are hierarchically nanostructured microspheres assembled from nanosheets. The PL spectra indicate that the 5D4→7F5 (545 nm) electric dipole transition is the most intensive when excited at 235 nm. It is shown that 0.7 mol% of doping concentration of Tb3+ ions in γ-Al2O3:Tb3+ is optimum. According to Dexterʹs theory, the critical distance between Tb3+ ions for energy transfer was determined to be 18.4 Å. It is found that the curve followed the single-exponential decay. The excellent chromaticity coordinates of Al2O3:Tb3+ phosphors, as defined by the International Commission on Illumination (CIE), indicate that it is a good candidate for use in light display systems and optoelectronic devices.