Qin Laishun

Temperature dependence of the luminescence properties of LaCl3:Ce crystal

The optical properties of LaCl3:Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is found that optical transmittance is as high as 80% between 320 nm and 600 nm, and no obvious absorption band is found in this region. Emission intensity and decay time of photoluminescence are quite stable with the change of the temperature between 80 K and 500 K. No thermal quenching is present up to 500 K, and decay time keeps at 17±2 ns. With the increase of the temperature, the whole emission bands and excitation bands present broadening and overlapping, leading to the strengthening of re-absorption of the Ce3+ emission, which makes the emission spectra have a red shift trend.

Influence of Self-Absorption and Impurities on Scintillation Properties of (Lu0.1Y0.9)AlO3:Ce Single Crystals

Lu0.1Y0.9AlO3:Ce single crystals in dimensions ?30?90?mm3 are successfully grown by the Czochralski method. The light output and energy resolution of the crystal in dimensions ?14?2?mm3 are 9420 photons/MeV and 12.5% respectively. Dependence of the light output on the thickness of the sample is found and explained by the self-absorption in the range of 320?370?nm and the underlying parasitic absorption around 250?nm. In addition, the local enrichment of Ce ions and the presence of low-valent impurity ions may cause the deterioration of its light output. In addition, Lu0.1Y0.9AlO3:Ce has an almost constant fluorescence decay time of 16?ns in the temperature range of 80?373?K.

Radiation Induced Optical Absorption of Cubic Lead Fluoride Crystals and the Effect of Annealing

Transparent and colorless lead fluoride crystals with sizes of 20 × 20 × 20 (mm3) are irradiated with several doses of γ-rays from a 60 Co source. Their transmittance spectra before and after irradiation are measured, and a new parameter ΔT = Tb − Ta is defined to evaluate the irradiation damage. Three optical absorption bands peaking at 270 nm, 370 nm and 500 nm are found in the plots of ΔT versus wavelength, and their intensities increase with the irradiation dose. These optical absorption bands, except the one at 270 nm, can recover spontaneously with time. Thermal annealing treatment can enhance this recovery of the transmittance, while the optimum annealing temperature for different samples depends on the irradiation dose.

Growth and Scintillation Properties of La(Cl0.05Br0.95)3:Ce Crystal

The growth and scintillation properties of La0.97 (Cl0.05Br0.95)3:Ce0.03 crystals are reported. A 1-inch-diameter as-grown crystal is achieved by applying the vertical Bridgman technique, and one machined single crystal with sizes 18 mm × 8 mm × 8 mm is acquired. The scintillation properties of La0.97 (Cl0.05Br0.95)3:Ce0.03 crystals are presented. Under the excitation of UV (ultraviolet) light, the crystal exhibits two luminescent peaks centered at 358 nm and 382 nm. The light output is about 62000 ph/MeV while the energy resolution (ΔE/E) of this crystal at 662 keV is 4.55% of the full width at half-maximum. Additionally, the crystal photoluminescence decay time constant is 17.7 ns, which is significantly faster than that of LaBr3:Ce. The results indicate that the LaCl3 and the LaBr3 can form the anion solid solution crystal. The Lax (ClyBr1−y)3:Cei−x crystal is potentionally a promising scintillator.