Local microstructure and photoluminescence of Er-doped 12CaO center dot 7Al(2)O(3) powder

Er-doped 12CaO center dot 7Al(2)O(3) (C12A7:Er) powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction (XRD), Raman and absorption spectra revealed that Er ions existed and substituted Ca2+ lattice site in MAT The photoluminescence of C12A7:Er at room temperature was observed in the visible and infrared region using 488 nm (2.54 eV) Ar+ line as excitation source, respectively. The sharp and intense green emission bands with multi-peaks around 520 nm and 550 nm correspond to the transitions from the excited states H-2(11/2) and S-4(3/2) to the ground state I-4(15/2), respectively. Furthermore, red emission band around 650 nm was also observed. It was attributed to the electronic transition from excited states F-4(9/2) to the ground state I-4(15/2) inside 4f-shell of Er3+ ions. The intensive infrared emission at 1.54 mu m was attributed to the transition from the first excited states of I-4(13/2) to the ground state (I-4(15/2)). The temperature dependent photoluminescence of infrared emission showed that the integrated intensity reached a maximum value at near room temperature. The forbidden transitions of intra-4f shell electrons in free Er3+ ions were allowed in C12A7 owing to lack of the inversion symmetry in the Er3+ position in C12A7 crystal field. Our results suggested that C12A7:Er was a candidate for applications in Er-doped laser materials, and full color display.