On low-temperature luminescence quenching in Gd3(Ga,Al)5O12:Ce crystals

Abstract

Temperature dependences of the photoluminescence and X-ray excited luminescence intensity and thermally stimulated luminescence glow curves are measured in the 4.2-300 K temperature range for the undoped and Ce 3+-doped Gd3(Ga,Al)5O12 crystals. The conclusion is made that no low-temperature quenching of the Ce 3+-related photoluminescence takes place. In both the undoped and the Ce 3+-doped crystals, temperature dependences of the X-ray excited recombination luminescence intensity correlate with the position and shape of thermally stimulated luminescence glow curve peaks of the hole origin. Low-temperature quenching of the X-ray excited luminescence in these crystals is explained by the fact that at low temperatures, free holes are trapped at oxygen ions while electrons are trapped at various intrinsic defects. In Ce 3+doped Gd3(Ga,Al)5O12 crystals, thermally stimulated release of the trapped holes and electrons and their subsequent recombination at Ce 3+ ions result in the enhancement of the Ce 3+-related electron recombination luminescence with the increasing temperature in the 10-180 K range.

On the Quenching Mechanism of Ce, Tb Luminescence and Scintillation in Compositionally Disordered (Gd, Y, Yb)3Al2Ga3O12 Garnet Ceramics

“…In fact, it shows a behavior that is close to the results described in [50]. However, the activation energy was defined to be 9.5 meV, which is two times less than in GAGG:Ce [51]. Most likely, this difference is caused by the additional quenching effect by Yb ions in the matrix.…”

Effect of W and Mo co-doping on the photo- and thermally stimulated luminescence and defects creation processes in Gd3(Ga,Al)5O12:Ce crystals

“…Unlike the GAGG:Ce (Prague) crystal investigated in [21][22][23][24] and the GAGG:Ce crystal investigated in this work, the position of the Ce 3+ -related emission band of the GAGG:Ce, 0.1% W crystal depends on the excitation energy Eexc (see Fig. 1).…”

“…Host composition GAGG:Ce, 0.1% W Gd2.81-2.85Ga2.95-3.00Al2. For comparison, the characteristics of the undoped Gd3GaxAl5-xO12 (x = 3) and the Gd3GaxAl5-xO12:0.035% Ce (x = 2.83) single crystals, grown by the Czochralski method in Prague, Institute of Physics and studied in our previous works [21,22,23,24], were measured at the same experimental conditions. These crystals are denoted as the GAGG (Prague) and GAGG:Ce (Prague) crystals.…”

“…Indeed, as the electrons recombination with the intrinsic hole centers results in the appearance of the intrinsic luminescence of GAGG, this fact could explain a large contribution of the intrinsic emission band into the luminescence spectrum of GAGG:Ce,W. According to [24], the TSL peaks of a hole origin should contribute into the complex TSL glow peaks located around 70 K and 220-250 K and observed in the undoped GAGG crystal Xray irradiated at 9 K. This conclusion has been confirmed by a relatively small values of the frequency factors obtained for both these peaks in the undoped GAGG crystal (f0 ~ 10 7 s -1 [21]). However, in the investigated crystals not only the 106 -108 K peak but also the peak at 250 -252 K (with relatively large f0 ~ 5x10 10 -10 11 s -1 , see Table 3) should be mainly of an electron origin.…”

“…9, black line) and in the energy range between the 4f -5d2 and 4f -5d1 absorption bands of Ce 3+ (with Eexc = 3.27 eV, red line). This effect is surely connected with the presence in the crystals of Mo 6+ ions as no dependence of the emission spectra on the excitation energy is observed in Mo -free GAGG:Ce crystals (see, e.g., [21][22][23][24]). The excitation spectrum of the Ce 3+ -related emission of the GAGG:Ce,Mo crystal (Fig.…”