Single crystals of Gd3Ga3Al2O12 : Ce with different codopants were successfully grown using the Czochralski technique. Optical and scintillation properties of these codoped crystals were studied in detail including absorption, photoluminescence excitation and emission, decay time and thermoluminescence. This study revealed that while boron codoping improves the scintillation light output and energy resolution and decreases self-absorption in these crystals, calcium codoping affects their properties in the opposite manner. In addition to antisite defects, the effect of room temperature trap centres on the sensitivity of these crystals to light exposure is also reported for the first time. Light sensitivity was also found to be affected with the incorporation of codopants in the lattice. The effect of annealing in oxidizing and reducing atmospheres on the scintillation and optical properties of differently codoped crystals was also investigated in detail in order to better understand the defect structure of these crystals. All these measurements together are used to explain the effect of codoping on the crystal field and defect structure of these crystals.

http://iopscience.iop.org/article/10.1088/0022-3727/46/47/475302/pdf

Effect of codoping on scintillation and optical properties of a Ce-doped Gd 3 Ga 3 Al 2 O 12 scintillator

In order to enhance capabilities for the reliable detection of nuclear material, improved detector materials are required. There is considerable room for improvement within the scintillator family of materials. However, native defects are present in all materials and impurities are similarly common. In scintillators, these defects serve as trap sites for electrons or holes, and therefore may contribute to decreased and delayed light yield. In fact, Lempicki and Bartram [J. Lumin. 81 (1999) 13] have proposed that understanding defect related phenomena is vital to the improvement of scintillators. It follows that if the most egregious electron/hole trapping defects are removed from the system, light output should increase. However, defect removal is difficult to achieve since often the defect-type to be removed is not known. In this paper, we assist the optimization of scintillators by employing atomic scale simulation techniques to predict the intrinsic defect structure of RE 3 Al 5 O 12 garnets (where RE ranges from Lu to Gd and Y). Specifically, we predict cation antisite defects to be the lowest energy intrinsic defect. Furthermore, we describe how our results can be used to interpret experimental observations.

The effect of intrinsic defects on RE3Al5O12 garnet scintillator performance

Luminescence properties of Tb3+:Y3Al5O12 nanocrystallites prepared by the sol–gel method

Synthesis of garnet structure compounds using aqueous sol–gel processing

The aim of this work is to investigate the feasibility of the use of titanium dioxide (TiO2), zinc oxide (ZnO), copper oxide (CuO) and Cadmium oxide (CdO) in the development of thick film gamma radiation sensors with instantaneous dosage readouts. A number of pn-heterojunctions with various compositions of sensitive layers were formed by screen printing the thick film pastes on silicon wafers. All these devices were exposed to a disc-type 137Cs source with an activity of 370 kBq. It was found that for all samples the values of leakage current increased with increasing radiation dose.

Gamma radiation sensing properties of TiO2, ZnO, CuO and CdO thick film pn-junctions

Excitation-mission spectra have been measured for Pr3+, Ce3+, Nd3+ and Eu3+ doped YAP, YAG, and SLGO crystals in room temperature Results of additional absorption measurements and changes in a luminescence after gamma irradiation with dose up to 105 Gy and energy of 25 MeV are also presented© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only

Excitation emission spectra of laser materials for UV-VIS range

Changes in optical properties of some oxide compounds (YAG, YAG:Nd 3+ , YAG:Ce 3+ , YAG:Ce 3+ ,Mg 2+ , YAG:Cr 3+ , YAG:Cr 4+ , SrLaGa3O7:Dy 3+ , SrLaGa3O7:Cr 3+ , SrGdGa3O7:Cr 3+ , LiNbO3:Cr 3+ and LiNbO3:Cu 2+ ) induced by 21 MeV proton irradiation were studied. In the optical absorption spectra lines which belong to optically active dopants (like Ce 3+ , Cr 3+ , Fe 3+ ) and F-type color centers are seen. Influence of proton irradiation on such centers is observed. It seems to be attributed to the ionization and/or recombination of definite centers. Moreover, for relatively high proton fluencies, Frenkel defects are probably created.

Interaction of protons with oxide compounds

-y and electron as grown crystals were used while for proton irradiations the crystals were thermally annealed. For small concentrations of cerium ions (u 0.01 at.%) an increase in the lumi- nescence (about 100%) was observed after gamma irradiation with a dose of 10 5 Gy. This increase was due to the growth in Ce 3 + ions concentration after γ-irradiation (= 50%), due to the Ce 4 + -> Ce 3reaction. For highly doped Ce:YAG crystals (0.1 at%, 0.2 at.%) also an increase, but much smaller (4%), for the Mg codoped crystals (0.1 at.%) was observed. After 1 MeV electron irradiation in the over-threshold type interaction a de- crease in luminescence is observed due to the domination of the Ce3+ -> C e4+ ionization process. In the case of the proton irradiation, for small fluencies (Pe. 10 13 particles/cm 2 ) an increase in luminescence is observed due to the domination of the recharging processes of Ce

/pdf/changes-in-luminescence-of-ce-yag-crystals-under-ionizing-42kr98djph.pdf

CHANGES IN LUMINESCENCE OF Ce:YAG CRYSTALS UNDER IONIZING RADIATION TREATMENT*

Gamma-induced transition of Ce4+ $ARLR Ce3+ was investigated for Ce,Nd:YAG samples cut off from the same crystal and differing one to another by a few tenth percent of Ce3+ ions concentration (starting concentration). Depending on the starting concentration changes of resulting concentration of Ce3+ ions were observed. The luminescence of Ce,Nd:YAG crystal at about 530 nm increased independently on Ce3+ starting concentration.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Z. Moroz

Papers

Excitation emission spectra of laser materials for UV-VIS range

Interaction of protons with oxide compounds

CHANGES IN LUMINESCENCE OF Ce:YAG CRYSTALS UNDER IONIZING RADIATION TREATMENT*

Gamma-induced effect of recharging: Ce4+--Ce3+ in Ce3+ and Nd3+ doped YAG crystals

Otrzymywanie i właściwości optyczne monokryształów granatu itrowo-aluminiowego domieszkowanych cerem i magnezem