Abstract :
Yttrium–aluminum oxides are interesting
compounds, which are widely used as hosts for lasers
and phosphors due to their stable physical and chemical
properties. The manufacture of YAG has been
investigated thoroughly. YAG powders are traditionally
synthesized through the reaction of aluminum and
yttrium powders at high temperatures. The work
reported here involved an investigation into the preparation
of YAG by a nonhydrolytic sol-gel route and
the influence of heating time at low temperatures to
obtain YAG from inorganic precursors (yttrium and
aluminum chloride). AlCl3, YCl3 and ethanol were
reflux reacted under an argon atmosphere. Europium
III chloride was added as a structural probe. The
powder was treated at 800 C for 1, 2, 4, 8 and 16 h.
The YAG structure was analyzed by X-ray diffraction
(XRD), nuclear magnetic resonance (NMR), thermal
analysis (TA) and photoluminescence (PL). The XRD
revealed only peaks corresponding to the YAG phase.
PL data showed that the YAG phase was formed in
2 min with samples pretreated at 50 C. For the
samples pretreated at 800 C, the YAG phase
appeared in 30 s. The excitation spectra presented a
maximum of 394 nm corresponding to the 5L6 level,
while the emission spectra of Eu III ions showed
characteristic transition bands arising from the 5D0 fi
7FJ (J = 1, 2, 3, 4) manifolds at maximum excitation.
The magnetic dipole 5D0 fi 7F1 transition exhibited
greater intensity than the electric dipole 5D0 fi 7F2
transition. This methodology proved efficient for
obtaining YAG phase.
