Luminescent properties of Al2O3:Tb3+ nanoparticles obtained by cw CO2 laser vaporization

The synthesis of Al2O3:Tb3+ (0.019-0.62 mol%) nanoparticles by laser vaporization of alpha-Al2O3:Tb3+ ceramic targets using a cw CO2 laser in flowing helium at a pressure of 0.1 bar is reported. HRTEM, XRD and BET studies revealed that under the indicated conditions the produced Al2O3:Tb3+ nanoparticles have faceted and nearly a spherical shape with the average size below 10 nm. As shown by XRD, the phase composition of the synthesized nanoparticles is represented mostly by the low-temperature gamma-Al2O3. Photoluminescence (PL) spectra were obtained for Tb3+ ions in gamma-Al2O3 nanoparticles upon excitation to the 4f(8) -> 4f(7)5d (lambda(ex) = 230 nm), F-7(6) -> H-5(7) (lambda(ex) = 315 nm) and D-5(3) -> F-7(3) (lambda(ex) = 458 nm) transitions, and PL excitation spectra - for the most intense D-5(4) -> F-7(5) (lambda(max) = 543 nm) transition. The lifetime of the excited D-5(4) state was found to be ca. 2.9 ms. The obtained values of the chromaticity coordinate and absolute quantum yield were (0.299, 0.509) and 12.6% at lambda(ex) = 315 nm, respectively.