Temperature Quenching of Radio- and Photoluminescence of Y 3 (Ga,Al) 5 O 12 :Ce 3+ and Gd 3 (Ga,Al) 5 O 12 :Ce 3+ 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.