The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC cryst...The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.展开更多
Long persistent phosphors have received significant attention owing to their attractive photophysical properties.Here,we report a new long persistent phosphor exhibiting strong ultraviolet A(UVA)afterglow.The phosphor...Long persistent phosphors have received significant attention owing to their attractive photophysical properties.Here,we report a new long persistent phosphor exhibiting strong ultraviolet A(UVA)afterglow.The phosphors were synthesized by a solid-state reaction method.We find that the obtained phosphors demonstrate super long UVA-afterglow emissions after irradiation by X-ray source,and the afterglow can last more than 50 h.A wide range of experimental characterizations indicate that the Tb^3+doped fluoride elpasolite phosphors are defective and some fluoride ions are replaced by oxygen ions,which creates electron traps with suitable trap depths.Our results establish that Tb^3+can act as optical emitters in wide-bandgap hosts that can result in the UVA afterglow.This work enriches the bank of UV long persistent phosphors,and may stimulate more efforts for the design and synthesis of this kind of optical materials.展开更多
The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterizati...The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.展开更多
Currently,lead halide perovskite quantum dots(PeQDs)have attracted great attention due to their spectacular photophysical properties.However,the toxicity of Pb2+heavy metal ions in CsPbX3 PeQDs limits their practical ...Currently,lead halide perovskite quantum dots(PeQDs)have attracted great attention due to their spectacular photophysical properties.However,the toxicity of Pb2+heavy metal ions in CsPbX3 PeQDs limits their practical applications.Herein,a facile post-treatment doping method is proposed,which enables the preparation of highly luminescent low-toxic CsPbX3:Mn^2+PeQDs from nonluminescent Cs4PbX6 PeQDs at water interface.The monodispersed CsPbX3:Mn^2+PeQDs exhibit excellent photophysical properties,including high photoluminescence quantum yield up to 87%.The reaction process and doping mechanism are deeply explored through in-situ monitoring.By simply adjusting the halide composition of the original Cs4PbX6 PeQDs or Mn doping concentration,a series of CsPbX3:Mn^2+PeQDs with adjustable emission could be obtained.Further,the CsPbX3:Mn^2+Q-LED was fabricated and exhibited excellent orange light with the color coordinates of(0.564,0.399),correlated color temperature(CCT)of 1,918 K,and luminous efficiency(LE)of 24 lm/W,which illustrate the great promise in light emitting diode(LED)applications.This work not only provides a facile method for the preparation of highly luminescent low-toxic CsPbX3:Mn^2+PeQDs,but also provides insights into the mechanism of doping process.展开更多
The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and...The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and various rela ted aspects,such as the ways to determining various parameters,were summarized .The impacts of various interactions on the spectra were also demonstrated clea rly with Er3+ ions in crystals CaF2 and LiYF4.Predicted results were compared w ith measured spectra.展开更多
基金supported by the National Natural Science Foundation of China(No.11575145)
文摘The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.
基金supported by the National Natural Science Foundation of China(11574225,11874275)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)(61564007).
文摘Long persistent phosphors have received significant attention owing to their attractive photophysical properties.Here,we report a new long persistent phosphor exhibiting strong ultraviolet A(UVA)afterglow.The phosphors were synthesized by a solid-state reaction method.We find that the obtained phosphors demonstrate super long UVA-afterglow emissions after irradiation by X-ray source,and the afterglow can last more than 50 h.A wide range of experimental characterizations indicate that the Tb^3+doped fluoride elpasolite phosphors are defective and some fluoride ions are replaced by oxygen ions,which creates electron traps with suitable trap depths.Our results establish that Tb^3+can act as optical emitters in wide-bandgap hosts that can result in the UVA afterglow.This work enriches the bank of UV long persistent phosphors,and may stimulate more efforts for the design and synthesis of this kind of optical materials.
基金supported by the National Natural Science Foundation of China (21975032 and 21571020)the National Key Research and Development Program of China (2018YFA0702100)
文摘The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(No.U1905213).
文摘Currently,lead halide perovskite quantum dots(PeQDs)have attracted great attention due to their spectacular photophysical properties.However,the toxicity of Pb2+heavy metal ions in CsPbX3 PeQDs limits their practical applications.Herein,a facile post-treatment doping method is proposed,which enables the preparation of highly luminescent low-toxic CsPbX3:Mn^2+PeQDs from nonluminescent Cs4PbX6 PeQDs at water interface.The monodispersed CsPbX3:Mn^2+PeQDs exhibit excellent photophysical properties,including high photoluminescence quantum yield up to 87%.The reaction process and doping mechanism are deeply explored through in-situ monitoring.By simply adjusting the halide composition of the original Cs4PbX6 PeQDs or Mn doping concentration,a series of CsPbX3:Mn^2+PeQDs with adjustable emission could be obtained.Further,the CsPbX3:Mn^2+Q-LED was fabricated and exhibited excellent orange light with the color coordinates of(0.564,0.399),correlated color temperature(CCT)of 1,918 K,and luminous efficiency(LE)of 24 lm/W,which illustrate the great promise in light emitting diode(LED)applications.This work not only provides a facile method for the preparation of highly luminescent low-toxic CsPbX3:Mn^2+PeQDs,but also provides insights into the mechanism of doping process.
基金Project supported by the National Natural Science Foundation of China (10874173,10704090,11074315,11011120083)the Foundation of the Education Committee of Chongqing (KJ090523)the Knowledge Innovation Project of the Chinese Academy of Sciences (KJCX2-YW-M1)
文摘The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and various rela ted aspects,such as the ways to determining various parameters,were summarized .The impacts of various interactions on the spectra were also demonstrated clea rly with Er3+ ions in crystals CaF2 and LiYF4.Predicted results were compared w ith measured spectra.
