Temperature Quenching of Radio- and Photoluminescence of Y3(Ga,Al)5O12:Ce3+ and Gd3(Ga,Al)5O12:Ce3+ Garnet Ceramics

Cerium-doped mixed oxide garnets are promising luminescent materials to use as LED phosphors or scintillators for radiation detectors. In this paper, temperature-dependent characteristics of Ce-doped multicomponent garnets ceramics have been studied under photo and X-ray excitation. Ceramic samples of Y
₃
Ga
_x
Al
_5-x
O
₁₂
:Ce
_0.006
(
x
= 1 , 2, 3, and 4) and of Gd
₃
Ga
_x
Al
_5-x
O
₁₂
:Ce
_0.006
(
x
= 1 , 2, and 3) have been used. At high temperature, all samples showed decrease in the Ce
³⁺
luminescence intensity, luminescence decay, and luminescence lifetime due to thermal ionization of Ce
³⁺
excited 5d states. Values of activation energies of the thermal ionization process have been determined from photoluminescence lifetime measurements and shown in comparison with literature data. At low temperature, Gd-containing samples showed significant decrease in light output. In the same temperature range, large thermoluminescence peaks have been observed, indicating that the reduction of Ce
³⁺
emission at low temperatures can be attributed to the localization of charge carriers on traps.