Photoluminescence and electron-beam excitation induced cathodoluminescence properties of novel green-emitting Ba4La6O(SiO4)6:Tb3+phosphors

Tb3+ions activated Ba4La6O(SiO4)6 (BLSO:Tb3+) phosphors were synthesized by a citrate sol-gel method. The X-ray diffraction pattern confirmed their oxyapatite structure. The field-emission scanning electron microscope image established that the BLSO:Tb3+phosphor particles were closely-packed and acquired irregular shapes. The photoluminescence (PL) excitation spectra of BLSO:Tb3+phosphors showed intense f-d transitions along with low intense peaks corresponding to the f-f transitions of Tb3+ions in the lower energy region. The PL emission spectra displayed the characteristic emission bands of Tb3+ions, and the optimized concentrations were found to be at 1 and 6 mol% for blue and green emission peaks, respectively. The cathodoluminescece (CL) spectra exhibited a similar behavior that was observed in the PL spectra except the intensity variations in the blue and green regions. The CL spectra of the BLSO:6 mol% Tb3+phosphor unveiled accelerating voltage induced luminescent properties.