The intense blue emitting phosphors Sr2MgSiO5∶Ce 3+ were synthesized by high temperature solid state reaction method,and their luminescence properties were studied.The intense blue-emission band present a peak fixed ...The intense blue emitting phosphors Sr2MgSiO5∶Ce 3+ were synthesized by high temperature solid state reaction method,and their luminescence properties were studied.The intense blue-emission band present a peak fixed at 420 nm,which consists of two peaks located at 408 and 445 nm,respectively.The two peaks are originated from the transition 5d→ 2F 5/2（4f）and 5d→ 2F 7/2（4f）of Ce 3+ ions.The energy level difference value of the two emission bands is 2 038 cm-1,which is consistent with the theoretic value（2 000 cm-1）between the ground state:2F 5/2 and 2F 7/2 of Ce 3+ ions.The excitation spectra extend from 250 to 400 nm and the peak positions around 365 nm.In addition,the effect of the concentration of Ce 3+ ions and the role of charge compensation of different ions to the emission intense were investigated,the experiment results suggest that when the proportion of Ce 3+ ions to Sr2MgSiO5 were 0.03（molar ratio）,the strongest emission was obtained.Li+,Na+,K+ and Cl-ions can all enhance the intensity of the emissions;especially Cl-ions gave the best improvement.展开更多
The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays a...The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship,comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons,radioactive sources,and mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear decrease in the light yield,especially at energies below 400 keV.The NaI(Tl)crystal demonstrated an"excess"light output in the 6-200 keV range,reaching a maximum"excess"of 9.2%at 30 keV in the X-ray testing and up to 15.5%at 14 keV during Compton electron testing,indicating a significant advantage in the detection of low-energy gamma rays.Furthermore,we explored the underlying causes of the observed nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.展开更多
The green long-after-glow luminescence from Tb3＋-doped Sr2SiO4 phosphors, which are synthesized by the high temperature solid state reaction in a reductive atmosphere, is observed in this paper. The results show that...The green long-after-glow luminescence from Tb3＋-doped Sr2SiO4 phosphors, which are synthesized by the high temperature solid state reaction in a reductive atmosphere, is observed in this paper. The results show that under ultraviolet excitation, the obtained phosphors produce an intense green-lighting-emission from the Tb3＋, and the green-lighting long- after-glow luminescence related to Tb3＋ can last half an hour after the irradiation source has been removed. Moreover, the effects of co-doping Li＋, Dy3＋, Er3＋, Gd3＋, and Yb3＋ with Tb3＋ on the decay properties and thermoluminescence properties are investigated to confirm the long-after-glow mechanism.展开更多
文摘The intense blue emitting phosphors Sr2MgSiO5∶Ce 3+ were synthesized by high temperature solid state reaction method,and their luminescence properties were studied.The intense blue-emission band present a peak fixed at 420 nm,which consists of two peaks located at 408 and 445 nm,respectively.The two peaks are originated from the transition 5d→ 2F 5/2（4f）and 5d→ 2F 7/2（4f）of Ce 3+ ions.The energy level difference value of the two emission bands is 2 038 cm-1,which is consistent with the theoretic value（2 000 cm-1）between the ground state:2F 5/2 and 2F 7/2 of Ce 3+ ions.The excitation spectra extend from 250 to 400 nm and the peak positions around 365 nm.In addition,the effect of the concentration of Ce 3+ ions and the role of charge compensation of different ions to the emission intense were investigated,the experiment results suggest that when the proportion of Ce 3+ ions to Sr2MgSiO5 were 0.03（molar ratio）,the strongest emission was obtained.Li+,Na+,K+ and Cl-ions can all enhance the intensity of the emissions;especially Cl-ions gave the best improvement.
基金This work was supported by the National Key Research and Development Program(Nos.2022YFB3503600 and 2021YFA0718500)Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA15360102)National Natural Science Foundation of China(Nos.12273042 and 12075258).
文摘The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship,comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons,radioactive sources,and mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear decrease in the light yield,especially at energies below 400 keV.The NaI(Tl)crystal demonstrated an"excess"light output in the 6-200 keV range,reaching a maximum"excess"of 9.2%at 30 keV in the X-ray testing and up to 15.5%at 14 keV during Compton electron testing,indicating a significant advantage in the detection of low-energy gamma rays.Furthermore,we explored the underlying causes of the observed nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.
基金supported by the National Natural Science Foundation of China(Grant Nos.51272097,61265004,and 61265007)
文摘The green long-after-glow luminescence from Tb3＋-doped Sr2SiO4 phosphors, which are synthesized by the high temperature solid state reaction in a reductive atmosphere, is observed in this paper. The results show that under ultraviolet excitation, the obtained phosphors produce an intense green-lighting-emission from the Tb3＋, and the green-lighting long- after-glow luminescence related to Tb3＋ can last half an hour after the irradiation source has been removed. Moreover, the effects of co-doping Li＋, Dy3＋, Er3＋, Gd3＋, and Yb3＋ with Tb3＋ on the decay properties and thermoluminescence properties are investigated to confirm the long-after-glow mechanism.
