Papers by Keyword: Thermoluminescence (TL)

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Authors: Lin Zhang, Chen Shu Li, Hiroshi Yamada, Chao Nan Xu
Abstract: We have demonstrated a novel blue-violet emitting mechanoluminscent(ML) material with calcium aluminosilicate(CaAl2Si2O8:Eu2+). The ML was clearly visible to the naked eye in the atmosphere and showed a similar spectrum to photoluminescence with a peak at 430nm. In order to enhance the ML intensity, various rare earth ions were selected as co-dopants including La, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. It was found that the intensity of ML was strongly dependent on the kinds of the codoped rare earth ion, especially the co-doping of Ho3+ was found to greatly enhance the ML intensity. From the results of thermoluminescence(ThL) measurements, the enhancement of the ML intensity was closely related with the filled trap concentration and trap depth.
Authors: A. Halperin
Authors: Xiao Ning Wang, Jing Ning, Xiao Wei Fan, Chen Zhang, Xiao Sheng Huang, Ying Huang
Abstract: Briefly introduces the detection principle, characteristic and method of thermoluminescence dosimetry, and designs a set of data acquisition and processing system for thermoluminescence dosimeter reader. The device’s peripheral hardware circuit design is simple and scalable. This system can be applied to a variety of thermoluminescence dosimetry testing equipment.
Authors: C. Sallé, P. Grosseau, B. Guilhot, P. Iacconi, M. Benabdesselam, Gilbert Fantozzi
Authors: B.P. Chandra, V.K. Chandra, Piyush Jha
Abstract: Elastico-mechanoluminescence (EML) is a type of luminescence induced by elastic deformation of solids. The present paper reports the elastic-ML of thermoluminescent crystals such as X-or γ-irradiated alkali halide crystals, ZnS:Mn, and ultraviolet irradiated persistent luminescent crystals. Generally, all the elastico-mechanoluminescent crystals are thermoluminescent, but all the thermoluminescent crystals are not the mechanoluminescent. The elastico-mechanoluminescence spectra of crystals are similar to their thermoluminescence spectra. Both the elastico-mechanoluminescence and thermoluminescence arise due to the de-trapping of charge carriers. As elastico-ML of persistent luminescent crystals depends on both the density of filled traps and piezoelectric field, the intense thermoluminescent crystals may not be the intense mechanoluminescent crystals. When a sample of X-or γ-irradiated alkali halide crystal, UV-irradiated persistent luminescent microcrystals mixed in epoxy resin, or a film of ZnS:Mn nanoparticles is deformed in the elastic region by the pressure rising at fixed pressing rate for a particular time, or by a pressure of triangular form, or by a pressure pulse, then after a threshold pressure, initially the EML intensity increases with time, attains a maximum value and later on it decreases with time. In the first case, the fast decay time of EML is related to the time-constant for stopping the moving crosshead of the testing machine; in the second case, generally the fast decay does not appear; and in the third case, the fast decay time is equal to the rise time of the pressure pulse. However, in all the cases, the slow decay time is related to the lifetime of re-trapped charge carriers in the shallow traps lying in the region where the piezoelectric field is negligible. When the sample is deformed by the pressure rising at fixed pressing rate for a particular time, or pressure of triangular form, then the ML appears after a threshold pressure and the transient EML intensity increases linearly with the applied pressure; however, the total EML intensity increases quadratically with the applied pressure. The EML intensity of persistent luminescent crystals decreases with increasing number of pressings. However, when these crystals are exposed to UV light, then the recovery of EML intensity takes place. The mechanical interaction between the bending segment of dislocations and filled electron traps is able to explain the elastico-ML of X-or γ-irradiated alkali halide crystals. However, the piezoelectrically-induced de-trapping model is suitable for explaining the ML of persistent luminescent crystals and ZnS:Mn. The investigation of elastico-ML may be helpful in understanding the thermoluminescence and the investigation of thermoluminescence may be helpful in understanding elastico-ML. Furthermore, similar to the thermoluminescence, the mechanoluminescence may also find application in radiation dosimetry. Expressions are derived for the elastico-ML of thermoluminescent crystals, in which a good agreement is found between the experimental and theoretical results. Finally, the application of the elasticoML of thermoluminescent crystals in light sources, displays, imaging devices, sensing devices, radiation dosimetry and in non-destructive testing of materials are discussed.Contents of Paper
Authors: J.F. de Lima, G.O. Martins, Z.S. Macêdo, Mário Ernesto G. Valerio
Authors: C.M. Sunta, W.E.F. Feria Ayta, S. Watanabe
Authors: Ya Li, Yin Hai Wang, Yi Xiong, Tie Qiu Peng, Mao Song Mo
Abstract: (Eu, Dy) doped Sr3Al2O6 phosphors with high brightness and long afterglow were achieved by a high-temperature solid state reaction. Luminescence measurements indicate that the phosphor Sr3Al2O6:Eu prepared in normal atmosphere exhibits a sharp orange emission peaking at 591 nm excited by 221nm light, which is intrinsic f-f transition generated from Eu3+. Whereas, the phosphors Sr3Al2O6:Eu and Sr3Al2O6:Eu,Dy prepared in a weak reducing atmosphere show both a sharp orange emission peaking at 591nm excited by 221-nm light and a broad green emission peaking at 510nm excited by 328nm light, which resulted from Eu2+ transition between 4f65d1 and 4f7 electron configurations. The investigation results suggest that Eu3+ and Eu2+ co-exist in Sr3Al2O6 matrix synthesized in weak reducing atmosphere. In all samples, only Sr3Al2O6: Eu, Dy prepared in a weak reducing atmosphere has high intensity afterglow after excited by the UV source. The decay curve of Sr3Al2O6: Eu, Dy phosphor contains the rapid-decaying process and the slow-decaying process and can be fitted by a bi-exponential decay function. The measurement of thermal simulated luminescence demonstrates that only appropriate deep trap energy level and high trap concentration can generate optimum long-afterglow performance.
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