In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y2O3 are presented.Analysis on the phase and microstructures of the samples indicates that an additional phase is detected in the...In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y2O3 are presented.Analysis on the phase and microstructures of the samples indicates that an additional phase is detected in the samples doped with Y2O3,and the average grain size of the specimens decreases from about 9.2μm to 4.5μm,with an increase in the addition of Y2O3 from 0 mol%to 3 mol%.The corresponding varistor’s voltage gradient markedly increases from 462 V/mm to 2340 V/mm,while the nonlinear coefficient decreases from 22.3 to 11.5,respectively.Furthermore,the characteristics of deep trap levels in these ZnO samples are investigated by measuring their dielectric spectroscopies.The trap energy level and capture cross section evaluated by relaxation peak of the Cole-Cole plot vary slightly as the addition of Y2O3 increases.These traps may be ascribed to the intrinsic defects of ZnO lattice.展开更多
The long persistent phosphors Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02） were prepared by a high temperature solid state reaction. All samples showed a broad band emission peaking at 510 nm, which coul...The long persistent phosphors Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02） were prepared by a high temperature solid state reaction. All samples showed a broad band emission peaking at 510 nm, which could be ascribed to Eu2＋ transition between 4f65d1 and 4f7 electron configurations. With the increase of substitution of Ho3＋ ions for the Dy3＋ ions in the as-prepared phosphors Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02）, the initial intensity of the afterglow obviously decreased. From the thermoluminescence （TL） curves of the samples, we concluded that codoped Ho3＋ ions led to a decline of the trap depth and redistribution of the trap. This may be responsible for the change of afterglow of Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02）.展开更多
A new mixing method was developed for solid-state reaction synthesis of SrAl2O4:Eu2+,Dy3+ long afterglow phosphors.The morphology and crystal structure of the phosphors were analyzed with scanning electron microscope(...A new mixing method was developed for solid-state reaction synthesis of SrAl2O4:Eu2+,Dy3+ long afterglow phosphors.The morphology and crystal structure of the phosphors were analyzed with scanning electron microscope(SEM) and X-ray diffractometer(XRD).The excitation and emission spectra of the long afterglow phosphors were measured,and the main emission band was around 514 nm.The decay time of the product was measured and compared with the phosphors prepared using dry-mixing method and wet-mixing method.It ...展开更多
The DCM dye doped organic electroluminescence devices with structure of ITO/NPB/Alq 3:DCM/Alq 3/LiF/Al were fabricated.From 15 K to room temperature,the magnetic field dependent of electroluminescence(MEL)of devices w...The DCM dye doped organic electroluminescence devices with structure of ITO/NPB/Alq 3:DCM/Alq 3/LiF/Al were fabricated.From 15 K to room temperature,the magnetic field dependent of electroluminescence(MEL)of devices was investigated.Our observations indicated that the MEL is composed of two effects in different regimes:a low field(0≤B≤40 mT)effect and a high field(B】40 mT)effect.For undoped devices,the low field effect exhibits a rapid rising with the increasing field,and the high field effect shows a slow increase and gradually saturates at room temperature.For doped devices,the low field rapid increase is also present,whereas the high field effect displays a decrease with the increasing field.The larger the injection current is,the more apparent the high field decrease is.In addition,the doped device demonstrates less temperature dependence of the high field effect than undoped device,although the undoped devices also present high field decrease of electroluminescence at low temperatures(T≤150 K).Based on the energy level trapping effect due to dye doping and magnetic field modulated triplet exciton annihilation,the experimental results are carefully explained.展开更多
High-temperature polymer dielectrics with high energy density are urgently needed for capacitive energy storage fields.However,the huge conduction loss at elevated temperatures makes the capacitive performance of poly...High-temperature polymer dielectrics with high energy density are urgently needed for capacitive energy storage fields.However,the huge conduction loss at elevated temperatures makes the capacitive performance of polymers degrade sharply,limiting the application of them.Herein,the polymer dots(PDs)with high-electron-affinity were introduced into high-temperature polymers to prepare all-organic nanocomposite dielectrics by solution casting.It is found that polymer dots capture injected electrons via strong electrostatic attraction and impede charges transport and accumulation inside composites,thus reducing leakage current density and improving high-temperature energy storage performance.Consequently,the high-temperature capacitance performance of nanocomposites was improved significantly and reached over 2.5 times that of the pristine polymers,e.g.,the energy density of polyetherimide(PEI)/PD reached 3.24 J·cm^(-3)with excellent electrical fatigue reliability over 20,000 times.This work addresses the current problem of poor discharged energy density of polymer dielectrics at high temperatures with a simple and universal method.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.50425721 and 50737001)the 11th Five-year Natural S&T Supporting Plan of China(Grant No.2006 BAAO2A16)
文摘In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y2O3 are presented.Analysis on the phase and microstructures of the samples indicates that an additional phase is detected in the samples doped with Y2O3,and the average grain size of the specimens decreases from about 9.2μm to 4.5μm,with an increase in the addition of Y2O3 from 0 mol%to 3 mol%.The corresponding varistor’s voltage gradient markedly increases from 462 V/mm to 2340 V/mm,while the nonlinear coefficient decreases from 22.3 to 11.5,respectively.Furthermore,the characteristics of deep trap levels in these ZnO samples are investigated by measuring their dielectric spectroscopies.The trap energy level and capture cross section evaluated by relaxation peak of the Cole-Cole plot vary slightly as the addition of Y2O3 increases.These traps may be ascribed to the intrinsic defects of ZnO lattice.
基金Project supported by the National Natural Science Foundation of China (20871033)
文摘The long persistent phosphors Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02） were prepared by a high temperature solid state reaction. All samples showed a broad band emission peaking at 510 nm, which could be ascribed to Eu2＋ transition between 4f65d1 and 4f7 electron configurations. With the increase of substitution of Ho3＋ ions for the Dy3＋ ions in the as-prepared phosphors Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02）, the initial intensity of the afterglow obviously decreased. From the thermoluminescence （TL） curves of the samples, we concluded that codoped Ho3＋ ions led to a decline of the trap depth and redistribution of the trap. This may be responsible for the change of afterglow of Sr3Al2O6：Eu0.012＋,Dy0.02-x3＋,Hox3＋ （x=0, 0.01, 0.02）.
基金supported by the Program for New Century Excellent Talents in the University of China (NCET-06-0179)
文摘A new mixing method was developed for solid-state reaction synthesis of SrAl2O4:Eu2+,Dy3+ long afterglow phosphors.The morphology and crystal structure of the phosphors were analyzed with scanning electron microscope(SEM) and X-ray diffractometer(XRD).The excitation and emission spectra of the long afterglow phosphors were measured,and the main emission band was around 514 nm.The decay time of the product was measured and compared with the phosphors prepared using dry-mixing method and wet-mixing method.It ...
基金supported by For Ying Tung Education Foundation(Grant No.101006)the National Natural Science Foundation of China(Grant Nos.10974157 and 10974159)
文摘The DCM dye doped organic electroluminescence devices with structure of ITO/NPB/Alq 3:DCM/Alq 3/LiF/Al were fabricated.From 15 K to room temperature,the magnetic field dependent of electroluminescence(MEL)of devices was investigated.Our observations indicated that the MEL is composed of two effects in different regimes:a low field(0≤B≤40 mT)effect and a high field(B】40 mT)effect.For undoped devices,the low field effect exhibits a rapid rising with the increasing field,and the high field effect shows a slow increase and gradually saturates at room temperature.For doped devices,the low field rapid increase is also present,whereas the high field effect displays a decrease with the increasing field.The larger the injection current is,the more apparent the high field decrease is.In addition,the doped device demonstrates less temperature dependence of the high field effect than undoped device,although the undoped devices also present high field decrease of electroluminescence at low temperatures(T≤150 K).Based on the energy level trapping effect due to dye doping and magnetic field modulated triplet exciton annihilation,the experimental results are carefully explained.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51973080,92066104,and 52003099)Natural Science Foundation of Jilin Province(No.YDZJ202101ZYTS002)Capital Construction Fund of Jilin Province(No.2021C039-1).
文摘High-temperature polymer dielectrics with high energy density are urgently needed for capacitive energy storage fields.However,the huge conduction loss at elevated temperatures makes the capacitive performance of polymers degrade sharply,limiting the application of them.Herein,the polymer dots(PDs)with high-electron-affinity were introduced into high-temperature polymers to prepare all-organic nanocomposite dielectrics by solution casting.It is found that polymer dots capture injected electrons via strong electrostatic attraction and impede charges transport and accumulation inside composites,thus reducing leakage current density and improving high-temperature energy storage performance.Consequently,the high-temperature capacitance performance of nanocomposites was improved significantly and reached over 2.5 times that of the pristine polymers,e.g.,the energy density of polyetherimide(PEI)/PD reached 3.24 J·cm^(-3)with excellent electrical fatigue reliability over 20,000 times.This work addresses the current problem of poor discharged energy density of polymer dielectrics at high temperatures with a simple and universal method.
