Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothe...Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothermal reaction using commercially available Then single phase Gd2O2SO4：Pr powder was obtained by calcining the precursor at 750℃ for 2 h. The Gd2O2SO4：Pr powder compacts can be sintered to single phase Gd2O2S：Pr ceramics with a relative density of 99% and mean grain size of 30um at 1750℃ for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd2O2S：Pr ceramics were examined. Luminescence spectra of the Gd2O2S：Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the ^3p0-3H4 transition of Pr^3＋ ions.展开更多
Lanthanide(Ln^(3+))oxysulfide nanocrystals(NCs)have great prospect in many advanced technologies;however,they suffer from a low photoluminescence efficiency due to the volatility of sulfur and deleterious surface quen...Lanthanide(Ln^(3+))oxysulfide nanocrystals(NCs)have great prospect in many advanced technologies;however,they suffer from a low photoluminescence efficiency due to the volatility of sulfur and deleterious surface quenching effect.Herein,we report a novel sandwiched luminescent heterostructure based on Ln^(3+)-doped Gd_(2)O_(2)S@NaYF_(4)core/shell NCs with tunable sulfur content in the sandwich layer.By means of Eu^(3+)as the sensitive structural probes,we unravel the ligand-mediated structure control of the NCs from Gd_(2)O_(3):Ln^(3+)@NaYF_(4)to Gd_(2)O_(2)S:Ln^(3+)@NaYF_(4)with tailored S2–deficiency.Such a sandwich-type core/shell heterostructure enables us to achieve efficient and multicolor downshifting and upconversion luminescence(UCL),with up to 208.8 folds of enhancement in UCL intensity as compared to that of their core-only counterparts.These findings provide a general approach for the controlled synthesis of lanthanide oxysulfide@fluoride heterostructure,which offers a new way for the materials design towards diverse emerging applications.展开更多
Transparent Ce:lutetium aluminum garnet(Ce:Lu_(3)A_(l5)O_(12),Ce:LuAG)ceramics have been regarded as potential scintillator materials due to their relatively high density and atomic number(Zeff).However,the current Ce...Transparent Ce:lutetium aluminum garnet(Ce:Lu_(3)A_(l5)O_(12),Ce:LuAG)ceramics have been regarded as potential scintillator materials due to their relatively high density and atomic number(Zeff).However,the current Ce:LuAG ceramics exhibit a light yield much lower than the expected theoretical value due to the inevitable presence of LuAl antisite defects at high sintering temperatures.This work demonstrates a low-temperature(1100℃)synthetic strategy for elaborating transparent LuAG–Al_(2)O_(3) nanoceramics through the crystallization of 72 mol%Al_(2)O_(3)–28 mol%Lu_(2)O_(3)(ALu28)bulk glass.The biphasic nanostructure composed of LuAG and Al_(2)O_(3) nanocrystals makes up the whole ceramic materials.Most of Al_(2)O_(3) is distributed among LuAG grains,and the rest is present inside the LuAG grains.Fully dense biphasic LuAG–Al_(2)O_(3) nanoceramics are highly transparent from the visible region to mid-infrared(MIR)region,and particularly the transmittance reaches 82%at 780 nm.Moreover,LuAl antisite defect-related centers are completely undetectable in X-ray excited luminescence(XEL)spectra of Ce:LuAG–Al_(2)O_(3) nanoceramics with 0.3–1.0 at%Ce.The light yield of 0.3 at%Ce:LuAG–Al_(2)O_(3) nanoceramics is estimated to be 20,000 ph/MeV with short 1μs shaping time,which is far superior to that of commercial Bi_(4)Ge_(3)O_(12)(BGO)single crystals.These results show that a low-temperature glass crystallization route provides an alternative approach for eliminating the antisite defects in LuAG-based ceramics,and is promising to produce garnet-based ceramic materials with excellent properties,thereby meeting the demands of advanced scintillation applications.展开更多
Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_(2)Si_(2)O_(7):Ce polycrystalline...Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_(2)Si_(2)O_(7):Ce polycrystalline samples were successfully synthesized by a sol-gel method.The crystal structure and luminescence properties were confirmed and discussed by XRD,UV-Vis luminescence spectra,and XEL,respectively.The vacuum ultraviolet excitation spectra and thermoluminescence glow curves were also systematically investigated and discussed at varied temperature.A combination of the first-principles calculations and optical characterization experiments was employed to study the electronic band structure of host material,revealing that the band gap is narrowed and the 5d_(1) level of Ce^(3+) shifts to higher energy as the La content increases.The luminescence the rmo-stability and activation energy were also measured and calculated.It indicates that thermo-stability is strongly dependent on the La concentration.An effective approach is developed to tune the electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_(x))_(2)Si_(2)O_(7):Ce scintillator by adjusting La/Gd ratio.展开更多
基金National Natural Science Foundation of China(12175254,U1832119)National Key R&D Program of China(2021YFE0104800)+2 种基金International Partnership Program of Chinese Academy of Sciences(121631KYSB20200039)International Cooperation Project of Shanghai Science and Technology Commission(20520750200)National Centre for Research and Development(WPC2/1/SCAPOL/2021)。
基金supported by the National Natural Sci-ence Foundation of China (Grant. No. 50672014)the National Science Fund for Distinguished Young Scholars,China (Grant No. 50425413)
文摘Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothermal reaction using commercially available Then single phase Gd2O2SO4：Pr powder was obtained by calcining the precursor at 750℃ for 2 h. The Gd2O2SO4：Pr powder compacts can be sintered to single phase Gd2O2S：Pr ceramics with a relative density of 99% and mean grain size of 30um at 1750℃ for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd2O2S：Pr ceramics were examined. Luminescence spectra of the Gd2O2S：Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the ^3p0-3H4 transition of Pr^3＋ ions.
基金National Key R&D Program of China,Grant/Award Number:2022YFB3503700NSFC,Grant/Award Numbers:12074379,12174391,U22A20398,22135008+1 种基金the Youth Innovation Promotion Association of CAS,Grant/Award Number:2020305Natural Science Foundation of Fujian Province,Grant/Award Numbers:2020I0037,2021L3024,2022H0040。
文摘Lanthanide(Ln^(3+))oxysulfide nanocrystals(NCs)have great prospect in many advanced technologies;however,they suffer from a low photoluminescence efficiency due to the volatility of sulfur and deleterious surface quenching effect.Herein,we report a novel sandwiched luminescent heterostructure based on Ln^(3+)-doped Gd_(2)O_(2)S@NaYF_(4)core/shell NCs with tunable sulfur content in the sandwich layer.By means of Eu^(3+)as the sensitive structural probes,we unravel the ligand-mediated structure control of the NCs from Gd_(2)O_(3):Ln^(3+)@NaYF_(4)to Gd_(2)O_(2)S:Ln^(3+)@NaYF_(4)with tailored S2–deficiency.Such a sandwich-type core/shell heterostructure enables us to achieve efficient and multicolor downshifting and upconversion luminescence(UCL),with up to 208.8 folds of enhancement in UCL intensity as compared to that of their core-only counterparts.These findings provide a general approach for the controlled synthesis of lanthanide oxysulfide@fluoride heterostructure,which offers a new way for the materials design towards diverse emerging applications.
基金supported by the National Natural Science Foundation of China (No.51972304)Beijing Municipal Science&Technology Commission,Administrative Commission of Zhongguancun Science Park (No.Z221100006722022)+1 种基金the Project of Scientific Experiment on Chinese Manned Space Station,Chinese Academy of Sciences President’s International Fellowship Initiative for 2021 (No.2021VEA0012)the Fundamental Research Funds for the Central Universities.
文摘Transparent Ce:lutetium aluminum garnet(Ce:Lu_(3)A_(l5)O_(12),Ce:LuAG)ceramics have been regarded as potential scintillator materials due to their relatively high density and atomic number(Zeff).However,the current Ce:LuAG ceramics exhibit a light yield much lower than the expected theoretical value due to the inevitable presence of LuAl antisite defects at high sintering temperatures.This work demonstrates a low-temperature(1100℃)synthetic strategy for elaborating transparent LuAG–Al_(2)O_(3) nanoceramics through the crystallization of 72 mol%Al_(2)O_(3)–28 mol%Lu_(2)O_(3)(ALu28)bulk glass.The biphasic nanostructure composed of LuAG and Al_(2)O_(3) nanocrystals makes up the whole ceramic materials.Most of Al_(2)O_(3) is distributed among LuAG grains,and the rest is present inside the LuAG grains.Fully dense biphasic LuAG–Al_(2)O_(3) nanoceramics are highly transparent from the visible region to mid-infrared(MIR)region,and particularly the transmittance reaches 82%at 780 nm.Moreover,LuAl antisite defect-related centers are completely undetectable in X-ray excited luminescence(XEL)spectra of Ce:LuAG–Al_(2)O_(3) nanoceramics with 0.3–1.0 at%Ce.The light yield of 0.3 at%Ce:LuAG–Al_(2)O_(3) nanoceramics is estimated to be 20,000 ph/MeV with short 1μs shaping time,which is far superior to that of commercial Bi_(4)Ge_(3)O_(12)(BGO)single crystals.These results show that a low-temperature glass crystallization route provides an alternative approach for eliminating the antisite defects in LuAG-based ceramics,and is promising to produce garnet-based ceramic materials with excellent properties,thereby meeting the demands of advanced scintillation applications.
基金Project supported by the National Natural Science Foundation of China(11975220,51972291)the National Key Research and Development Program of China(2016YFB0700204)Natural Science Foundation of Shanghai(16ZR1441100)。
文摘Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_(2)Si_(2)O_(7):Ce polycrystalline samples were successfully synthesized by a sol-gel method.The crystal structure and luminescence properties were confirmed and discussed by XRD,UV-Vis luminescence spectra,and XEL,respectively.The vacuum ultraviolet excitation spectra and thermoluminescence glow curves were also systematically investigated and discussed at varied temperature.A combination of the first-principles calculations and optical characterization experiments was employed to study the electronic band structure of host material,revealing that the band gap is narrowed and the 5d_(1) level of Ce^(3+) shifts to higher energy as the La content increases.The luminescence the rmo-stability and activation energy were also measured and calculated.It indicates that thermo-stability is strongly dependent on the La concentration.An effective approach is developed to tune the electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_(x))_(2)Si_(2)O_(7):Ce scintillator by adjusting La/Gd ratio.
