The synthesis, physical characterization and cathodoluminescence (CL) of so
l-gel derived Y3-xAl5O12:Tb-x(3+) (YAG, x = 0.03-0.15) powders is presented
. Metal-alkoxide organic precursors were used as the starting materials to
form the sol-gel with the required stoichiometry. At a temperature between
900 and 950 degreesC the non-crystalline xero-gel fully crystallized to for
m the single-phase YAG powder. The powder X-ray diffraction showed that the
garnet structure and all reflections were indexed without any other second
ary impurity phases. From the CL spectrum, all possible transitions D-5(4)
--> F-7(1...6) due to Tb3+ in YAG structure were identified including the b
right green emission at 548 nm. The highest luminance at a fixed beam curre
nt density was observed for the Tb concentration of x = 0.12 (4% atomic). T
he CL intensity increased linearly with current densities from 1 to 60 muA/
cm(2) but remained nearly constant from 60 to 100 muA/cm(2). Two exponentia
lly decaying functions that were fitted to the pulsed-CL decay curve illust
rated the emission decay from D-5(4) and D-5(3) to F-7(J) levels with their
characteristic lifetimes. Both CL luminance and the decay time are compara
ble with commercially available optimized phosphors used for CRT and FED ap
plications. (C) 2001 Elsevier Science B.V. All rights reserved.