Photoluminescence and efficient energy transfer from Ce3+ to Tb3+ or Mn2+ in Ca9ZnLi(PO4)7 host

Structural and spectroscopic characterizations of the Ce3+/Tb3+(Mn2+) solely and Ce3+–Tb3+(Mn2+) doubly doped phosphate compound Ca9ZnLi(PO4)7 with β-Ca3(PO4)2 structure have been performed by powder X-ray diffraction and photoluminescence spectra measurements. The weak green emission from Tb3+ and red emission from Mn2+ are significantly enhanced by introduction of sensitizer Ce3+ ions due to an efficient resonant-type energy transfer from Ce3+ to activators Tb3+ or Mn2+. The energy transfer efficiency and the mechanism have been estimated based on spectroscopic data. Meanwhile, the critical distances for energy transfer between the Ce3+ and Tb3+ or Mn2+ ions are also calculated by the method of spectral overlapping.