  Photo- and thermally stimulated luminescence characteristics of
Gd3(Ga,Al)5O12:Ce single crystals co-doped with W and Mo are investigated in
the 85 - 510 K temperature range and compared with the corresponding
characteristics of the undoped and Ce3+ - doped Gd3(Ga,Al)5O12 single crystals
of similar composition. A strong effect of the W and Mo impurity ions appears
in the photoluminescence spectra and temperature dependences of the
photoluminescence intensity, afterglow intensity and decay kinetics, thermally
stimulated luminescence (TSL) intensity and TSL glow curves, excitation spectra
of the TSL glow curve peaks and activation energy of their creation. The
obtained results are explained by the enhancement of the intrinsic emission
contribution into the luminescence spectrum of Gd3(Ga,Al)5O12:Ce,W and
Gd3(Ga,Al)5O12:Ce,Mo due to a large concentration of various W - and Mo -
related electron traps in these crystals and, consequently, the O- - type hole
centers, as well as intrinsic crystal lattice defects (e.g., cation vacancies
needed for the excess positive charge compensation of the W6+ and Mo6+ ions).
The influence of the co-doping with W and Mo ions on the scintillation
characteristics of Gd3(Ga,Al)5O12:Ce is discussed.
