Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,K),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state reaction.All the p...Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,K),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state reaction.All the prepared phosphors formed a rhombohedral unit cell with the R3c space group.To improve the photoluminescence(PL)properties of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor,monovalent charge compensators such as Li^(+),NA^(+),and K^(+)were added to the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.The charge compensators acted as fluxes,so they improved the crystallinity.The excitation and emission properties were significantly improved through the incorporation of charge compensators.In particular,among the charge compensators,Li^(+)ion substantially enhanced the emission intensity and color purity.Furthermore,considering the evaporation of Li_(2)CO_(3)during the annealing process,we optimized the concentration of Li^(+)charge compensator to enhance its PL performance.Impressively,the green emission intensity of the Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.385 Li^(+)phosphor was 260%higher than that of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.We believe that the effect of charge compensators on the PL properties and the optimum concentration of Li^(+)cha rge compensator are useful for the design of phosphors in light-emitting diodes.展开更多
Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demon...Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demonstrated as a promising high-rate cathode material meeting the above requirements.Herein,we report the carbon decorated Li_(3)V_(2)(PO_(4))_(3) (LVP/C) cathode prepared via a facile method,which displays a remarkable high-rate capability and long-term cycling performance.Briefly,the prepared LVP/C delivers a high discharge capacity of 122 mAh g^(-1)(-93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles.Importantly,by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering,we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers.We show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles,which should be responsible for the remarkable electrochemical performance of LVP/C.Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP,which should be beneficial for the further design of high-performance LVP electrode materials.展开更多
A deep trench super-junction LDMOS with double charge compensation layer(DC DT SJ LDMOS)is proposed in this paper.Due to the capacitance effect of the deep trench which is known as silicon-insulator-silicon(SIS)capaci...A deep trench super-junction LDMOS with double charge compensation layer(DC DT SJ LDMOS)is proposed in this paper.Due to the capacitance effect of the deep trench which is known as silicon-insulator-silicon(SIS)capacitance,the charge balance in the super-junction region of the conventional deep trench SJ LDMOS(Con.DT SJ LDMOS)device will be broken,resulting in breakdown voltage(BV)of the device drops.DC DT SJ LDMOS solves the SIS capacitance effect by adding a vertical variable doped charge compensation layer and a triangular charge compensation layer inside the Con.DT SJ LDMOS device.Therefore,the drift region reaches an ideal charge balance state again.The electric field is optimized by double charge compensation and gate field plate so that the breakdown voltage of the proposed device is improved sharply,meanwhile the enlarged on-current region reduces its specific on-resistance.The simulation results show that compared with the Con.DT SJ LD-MOS,the BV of the DC DT SJ LDMOS has been increased from 549.5 to 705.5 V,and the R_(on,sp) decreased to 23.7 mΩ·cm^(2).展开更多
In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles a...In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles are studied by soft x-ray absorption spectroscopy in total electron（TEY） and fluorescence（TFY） detection modes, which provide surface and bulk information, respectively. The spectra of Co L2,3-edge indicate that Co contributes to charge compensation below 4.4 V.Combining with the spectra of O K-edge, it manifests that only O contributes to electron compensation above 4.4 V with the formation of local O 2 p holes both on the surface and in the bulk, where the surficial O evolves more remarkably. The evolution of the O 2 p holes gives an explanation to the origin of O2^-or even O2. A comparison between the TEY and TFY of O K-edge spectra of LiCoO2 cycled in a range from 3 V to 4.6 V indicates both the structural change in the bulk and aggregation of lithium salts on the electrode surface are responsible for the capacity fading. However, the latter is found to play a more important role after many cycles.展开更多
AIM: Variation in structure-related components in plant products prompted the trend to establish methods, using multiple or total analog analysis, for their effective quality control. However, the general use of routi...AIM: Variation in structure-related components in plant products prompted the trend to establish methods, using multiple or total analog analysis, for their effective quality control. However, the general use of routine quality control is restricted by the limited availability of reference substances. Using an easily available single marker as a reference standard to determine multiple or total analogs should be a practical option. METHOD: In this study, the Ultra-HPLC method was used for the baseline separation of the main components in ginseng extracts. Using a plant chemical component database, ginsenosides in ginseng extracts were identified by Ultra-HPLC-MS analysis. The charged aerosol detection(CAD) system with post-column compensation of the gradient generates a similar response for identical amounts of different analytes, and thus, the content of each ginsenoside in ginseng extracts was determined by comparing the analyte peak area with the reference standard(determination of total analogs by single marker, DTSM). The total ginsenoside content was determined by the summation of reference standard and other ginsenoside components. RESULTS: The results showed that DTSM approaches were available for the determination of total ginsenosides in a high purity ginseng extract because of the removal of impurities. In contrast, DTSM approaches might be suitable for determination of multiple ginsenosides without interference from impurities in the crude ginseng extract. CONCLUSION: Future practical studies similar to the present study should be conducted to verify that DTSM approaches based on CAD with post-column inverse gradient for uniform response are ideal for the quality control of plant products.展开更多
The relationship between the structural evolution and redox of Li-rich transition-metal layered oxides(LLOs)cathodes remains ambiguous,obstructing the development of high-performance lithium-ion(Li^(+))battery.Herein,...The relationship between the structural evolution and redox of Li-rich transition-metal layered oxides(LLOs)cathodes remains ambiguous,obstructing the development of high-performance lithium-ion(Li^(+))battery.Herein,the coherent effects of local atomic and electronic structure in Li_(2)Ru_(x)Mn_(1-x)O_(3)(LRMO)with a wide voltage window(1.3–4.8 V)is identified by in situ X-ray absorption fine spectroscopy(XAFS)and chemometrics.We not only skillfully separated the redox active structures to track the electrochemical path,but also visualized the coupling mechanism between the evolution of Ru-Ru dimer and the(de)excitation of cations and anions.Furthermore,introducing manganese triggers the“heterogeneity”of coordination environment and electronic structure between Ru and Mn after discharge to 3 V.The change of thermodynamic and kinetic paths affects the relithiation,and further leads to the hysteresis of the anion activation structure relaxation of Li_(2)Ru_(0.4)Mn_(0.6)O_(3)relative to Li_(2)RuO_(3)(LRO).Additionally,it is demonstrated that the high charge cut-off voltage restrains the relaxation of anionic active structure in LRO from a new perspective through comparative experiments.Our work associates the evolution of atomic structure with charge compensation and negative electrochemical reactions such as voltage hysteresis(VH)and capacity attenuation,deepening the understanding electrochemical reaction mechanism of LLOs during the first cycle and providing a theoretical support for the further design and synthesis of high-efficiency cathodes.展开更多
An analytical model of the power metal–oxide–semiconductor field-effect transistor(MOSFET)with high permittivity insulator structure(HKMOS)with interface charge is established based on superposition and developed fo...An analytical model of the power metal–oxide–semiconductor field-effect transistor(MOSFET)with high permittivity insulator structure(HKMOS)with interface charge is established based on superposition and developed for optimization by charge compensation.In light of charge compensation,the disturbance aroused by interface charge is efficiently compromised by introducing extra charge for maximizing breakdown voltage(BV)and minimizing specific ON-resistance(R_(on,sp)).From this optimization method,it is very efficient to obtain the design parameters to overcome the difficulty in implementing the R_(on,sp)–BV trade-off for quick design.The analytical results prove that in the HKMOS with positive or negative interface charge at a given length of drift region,the extraction of the parameters is qualitatively and quantitatively optimized for trading off BV and Ron,sp with JFET effect taken into account.展开更多
Based on particle-in-cell simulation, we studied the motions of ions and electrons. The results have shown that electrons are bounded by a magnetic field and only a small number of electrons can pass through the whirl...Based on particle-in-cell simulation, we studied the motions of ions and electrons. The results have shown that electrons are bounded by a magnetic field and only a small number of electrons can pass through the whirler channel. The plasma becomes non-neutral when it is emitted from the whirler, and the spatial charge leads to a beam divergence, which is unfavorable for mass separation. In order to compensate the spatial charge, a cathode is designed to transmit electrons and the quasi-neutral plasma beam. Experiment results have demonstrated that the auxiliary cathode can obviously improve the compensation degree of the spatial charge.展开更多
Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In...Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3＋ centers in Ca3Sc2Si3O12 by considering the effects of the charge com- pensations related to N3-, Sc3＋, Mn2＋, Mg2＋, and Na＋. Firstly, the local structures around Ce3＋ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce3＋ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3＋-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3＋ substituting Si4＋. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.展开更多
K2Ba（MoO4）2：Eu3＋ phosphors were synthesized by solid-state reaction. The emission and excitation spectra of K2 Ba（MoO4）2：Eu3＋ phosphors exhibited that the phosphors could be effectively excited by near ultravi...K2Ba（MoO4）2：Eu3＋ phosphors were synthesized by solid-state reaction. The emission and excitation spectra of K2 Ba（MoO4）2：Eu3＋ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet （394 nm） and blue （465 nm） light, and emitted red light at 616 nm. The influence of Eu3＋concentration, sintering temperature and charge compensators （K＋, Na＋ or Li＋ ） on the emission intensity were investigated. The results indicated that concentration quenching of Eu3＋ was not observed within 30mol.% Eu 3＋, 600 oC was a suitable sintering temperature for preparation of K2 Ba（MoO4）2：Eu3＋phosphors, and K＋ ions gave the best improvement to enhance the emission intensity. The CIE chromaticity coordinates of K2 Ba（MoO4）2：0.05Eu3＋phosphor were calculated to be （0.68, 0.32）, and color purity was 97.4%.展开更多
In the present study,Sm^(3+)activated inorganic orthophosphate CsMgPO_(4)(CSMP)phosphors were prepared by adopting a solid-state reaction method.The structural phase purity and morphological features were studied by X...In the present study,Sm^(3+)activated inorganic orthophosphate CsMgPO_(4)(CSMP)phosphors were prepared by adopting a solid-state reaction method.The structural phase purity and morphological features were studied by X-ray powder diffraction(XRD)and scanning electron microscopy(SEM),respectively.The molecular structure and vibrational modes were substantiated with the Fourier transform infrared spectroscopy(FTIR)and Raman spectroscopy characterization.The optical bandgap of the host and Sm^(3+)doped phosphors was deduced from the diffused reflectance(DR)spectra with a typical value of 5.72 eV and a small variation is observed with increasing concentrations.A systematic study of photoluminescence(PL)properties of Sm^(3+)doped CSMP phosphors was carried out.From the room temperature excitation and emission spectra,it is found that the phosphor emits in the orange rich red light under the suitable excitation of 402 nm in the UV region and concentration quenching occurs at x=0.02 doping level.The emission peaks observed at around 562,598 and 644 nm confirm the characteristic Sm^(3+)4 f-4 f transitions.The temperature-dependent photoluminescence(TD-PL)of the x=0.02(optimum doping)is recorded from 30 to 210℃,showing good thermal stability even at 150℃.The thermal quenching mechanisms are discussed based on the configuration coordinate model of excitation and emission.The prepared phosphors are found to exhibit near thermal stability compared to the commercially available red phosphors.PL decay time and quantum efficiency were measured.The colour coordinates are found to lie in the orangish-red region of the colour space.Thus the prepared phosphors CSMP:x Sm^(3+)can be useful as a red component in designing UV excitable chip-based phosphor-converted white LED applications.展开更多
In this study,K_(x)-Mn-Ce catalysts prepared by sol-gel method were investigated for toluene oxidation.Compared with Mn-Ce,the catalytic performance of K_(x)-Mn-Ce was further improved.X-ray diffraction(XRD),high reso...In this study,K_(x)-Mn-Ce catalysts prepared by sol-gel method were investigated for toluene oxidation.Compared with Mn-Ce,the catalytic performance of K_(x)-Mn-Ce was further improved.X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM)and Raman analyses demonstrate that K ions enter the lattice of CeO_(2) and disperse uniformly.The results of X-ray photoelectron spectroscopy(XPS),H_(2)-temperature programmed reduction(H_(2)-TPR).and O_(2)-temperature programmed desorption(O_(2)-TPD)analyses indicate that there is a strong interaction between K,Mn and Ce;the charge co mpensation effect would be induced when K ions enter the lattice of CeO_(2),which leads to more oxygen vacancies due to the generation of more Ce^(3+).Toluene-TPD shows that K-doping enhances the activation ability of toluene.Among all catalysts,K0.1-Mn-Ce shows the highest concentration of Mn^(4+),Ce^(3+),Osur,and redox ability,resulting in higher low-temperature catalytic activity.Additionally,the results of stability and water resistance also prove that K0.1-Mn-Ce catalyst possesses excellent stability and water resistance.展开更多
Trivalent samarium doped barium molybdate (BaMoO4:Sm3+) red phosphor was successfully synthesized by hydrothermal method. The crystal structure, morphology and photoluminescent property were characterized by X-ray dif...Trivalent samarium doped barium molybdate (BaMoO4:Sm3+) red phosphor was successfully synthesized by hydrothermal method. The crystal structure, morphology and photoluminescent property were characterized by X-ray diffraction, field environ-mental scanning electron microscopy and photoluminescence spectroscopy. The results indicated that the synthesized BaMoO4:Sm3+ phosphor consisted of a pure phase with an octahedral structure. The main excitation peaks were located at 362, 404, 445 and 477 nm, respectively, and were obviously observed. The main emission peaks were located at 533, 566, 602 and 646 nm, respectively. The phosphors exhibited a red performance at 646 nm, which was appropriate for the ultraviolet-light emitting diode (UV-LED) and blue LED. The luminescent intensity of BaMoO4:Sm3+ increased with an increase in the doping amount of Sm3+. The luminescent intensity had the optimal value forx=0.03. When the doping amount of Sm3+ was further increased, the concentration quenching phenomenon was observed. Monovalent lithium (Li+) cation was used as a charge compensator. The luminescence intensity first increased with in-creasing Li+ doping concentration, and then decreased. The optimal content of Li+ was about 2%. The BaMoO4:Sm3+ phosphor pre-pared in this study could act as superior red phosphor for white LEDs.展开更多
The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to AP＋ in the molten slags, so that the deviations between the calcul...The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to AP＋ in the molten slags, so that the deviations between the calculated values and measured ones of sulfide capacity are inevitable. The relation between sulfide capacity and the corrected optical basicity put forward by Mills considering the charge compensation was investigated. Combined with the relation be- tween sulfide capacity and temperatures, a novel and accurate calculation model of sulfide capacity was proposed, which was applied to calculate the sulfide capacities of CaO-Al2 O3-SiO2-MgO and CaO-Al2 03-SiO2-MgO-TiO2 sys-tems, where the sum of the CaO and MgO concentrations in the slags must be not lower than the Al2O3 concentra tion. It was also found that the calculated values were in a good agreement with the measured values, and the mean deviations were 2.57% and 2.65%, respectively.展开更多
A series of CaMoO4 phosphors doped with trivalent dysprosium ions （Dy3＋） and lithium （Li＋） were prepared by solid state method at 750 °C for 3 h. X-ray diffraction （XRD） confirmed the crystal structure an...A series of CaMoO4 phosphors doped with trivalent dysprosium ions （Dy3＋） and lithium （Li＋） were prepared by solid state method at 750 °C for 3 h. X-ray diffraction （XRD） confirmed the crystal structure and quality of phosphors. Scanning electron microscopy （SEM） in- dicated that the phosphors presented good crystalline state, and the crystalline grain sizes were about 0.5–3.0 μm. The emission spectra showed that the phosphors had intense emission at 480 （4F9/2→6H15/2）, 576 （4F9/2→6H13/2） and 660 nm （4F9/2→6H11/2）. Meanwhile, the excited spectra indicated it had intense excitation at 352 （6H15/2→6P7/2）, 390 （6H15/2→4M21/2） and 450 nm （6H15/2→4I15/2）. As a charge compensator, Li＋ ions were incorporated into CaMoO4：Dy3＋ phosphors, which enhanced the PL intensities depending on the doping concentration of Li＋. The optimal molar fraction of Dy3＋ ions in Ca1-xMoO4：xDy3＋, 0.05Li＋ was 0.05.展开更多
Viscosity is an important physical property of blast furnace slags and has a great influence on blast furnace operations. Because of time consumption and difficulties encountered during high temperature experimental m...Viscosity is an important physical property of blast furnace slags and has a great influence on blast furnace operations. Because of time consumption and difficulties encountered during high temperature experimental measurement, viscosity data are also limited, so a rea-sonable and accurate estimation model is required to provide the data for controlling and optimizing the blast furnace process. In the present study a viscosity model was proposed for blast furnace slags. In the model the activation energy was calculated by the optical basicity cor-rected for cations required for the charge compensation of , and the temperature dependence was described by the Weymann-Frenkel equation. The estimated viscosity values of the CaO-Al2O3-SiO2, CaO-Al2O3-SiO2-MgO, and CaO-Al2O3-SiO2-MgO-TiO2 systems fit well with experiment data, with the mean deviation less than 25%.展开更多
The SrTiO3 ： Pr^3＋ material, co-doped with monovalent Li^＋ , divalent Mg^2＋ , and trivalent Al^3＋ was prepared by a new sol-gel method. The phase and crystallinity of the synthesized materials were investigated b...The SrTiO3 ： Pr^3＋ material, co-doped with monovalent Li^＋ , divalent Mg^2＋ , and trivalent Al^3＋ was prepared by a new sol-gel method. The phase and crystallinity of the synthesized materials were investigated by powder X-ray diffraction（XRD） and scanning electron microcopy（SEM）. Among the co-doped ion, Al^3＋ incorporation caused the least lattice change and had the best crystallinity. Photoluminescence spectra were taken to investigate the luminescence characteristics. We observed a red luminescence change of SrTiO3 ： Pr^3＋ after being co-doped, and a best enhancement on the red luminescence with the trivalent Al^3＋ was observed. The present results indicated that the charge defect associated with Al^3＋ has led to charge compensation of Pr^＋ and also implied that the charge defects（usually the second dopant ions replacing the A or B sites in the lattice） which are closer to PrSr^＋ contribute more to the red luminescence enhancement.展开更多
Blue-emitting phosphors Sr_(6)Ca_(4)(PO_(4))_(6) F_(2):Eu^(2+)(SCPF:Eu^(2+)),Sr_(6 )Ca_(4)(PO4)6 F_(2):Eu^(2+),Dy^(3+)(SCPF:Eu^(2+),Dy^(3+))and Sr_(6)Ca_(4)(PO4)6 F_(2):Eu^(2+),Dy^(3+),Si^(4+)(SCPF:Eu^(2+),Dy^(3+),Si^...Blue-emitting phosphors Sr_(6)Ca_(4)(PO_(4))_(6) F_(2):Eu^(2+)(SCPF:Eu^(2+)),Sr_(6 )Ca_(4)(PO4)6 F_(2):Eu^(2+),Dy^(3+)(SCPF:Eu^(2+),Dy^(3+))and Sr_(6)Ca_(4)(PO4)6 F_(2):Eu^(2+),Dy^(3+),Si^(4+)(SCPF:Eu^(2+),Dy^(3+),Si^(4+)) with apatite structure were successfully synthesized by traditional solid-state reaction under reducing atmosphere.Eu^(2+),Dy^(3+) and Si^(4+)ions occupy the corresponding sites of Sr^(2+),Ca^(2+) and P5+.Strong broad blue photo luminescence band is exhibited in SCPF:Eu^(2+),Dy^(3+) phosphor ranging from 400 to 550 nm centered at 455 nm and Dy^(3+) ions are vital in creating traps.Emission intensity of Eu^(2+),Dy^(3+) co-doped SCPF:0.02 Eu^(2+),0.02 Dy^(3+) is about 1.8 times that of SCPF:0.02 Eu^(2+) and electron trap centers serve as energy transporting media.To further elucidate the formation and effect of the specific defect on the luminescence of SCPF:0.02 Eu^(2+),0.02 Dy^(3+) phosphor,the thermoluminescence properties,decay curves and thermal stability studies were performed while the Si^(4+)-P^(5+) charge compensated pho sphor SCPF:0.02 Eu^(2+),0.02 Dy^(3+),0.02 Si^(4+) was prepared as a contrast.All the results of present work indicate that Dy^(3+) co-doping can obviously enhance photoluminescence intensity of SCPF:0.02 Eu^(2+) by the electron traps generated by non-equivalence replacement of Dy^(3+)-Ca^(2+).展开更多
Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Un...Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs_3Zn_(5.94)B_9O_(21):0.06Eu^(3+)possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li^(+)ions into the lattice,the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect.Then,under the stimulus of high temperature,the corresponding trap levels with a suitable depth(E=1.27 eV)will release electrons to recombine with the luminescent centers,compensating for the energy loss.The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.展开更多
A series of red-emitting phosphors of CaBi2Ta2O9：Pr3＋ and CaBi2Ta2O9：Eu3＋ were synthesized by the solid-state reaction method. The crystal structure and photoluminescence properties were investigated by X-ray diff...A series of red-emitting phosphors of CaBi2Ta2O9：Pr3＋ and CaBi2Ta2O9：Eu3＋ were synthesized by the solid-state reaction method. The crystal structure and photoluminescence properties were investigated by X-ray diffraction （XRD） and photoluminescence spectra. The emission spectra showed that the red emission peaks were located at 622 nm for Pr3＋ and 615 nm for Eu3＋, respectively. The optimal doping concentrations for Ca1-xBi2Ta2O9：xPr3＋ and Ca1-yBi2Ta2O9：yEu3＋ were x=0.02 and y=0.15, respectively. The effect of fluxes （H3BO3, NH4F, CaCl2 and CaF2） and charge compensations （Li2CO3, Na2CO3 and K2CO3） on luminescent properties were investigated in detail. It was found that the relative emission intensity of Ca0.98Bi2Ta2O9：0.02Pr3＋ with 10 mol.% H3BO3 flux was about 2.9 times higher than that of the sample without flux. The relative emission intensity of Ca0.7Bi2Ta2O9：0.15Eu3＋, 0.15K＋ was about the 2.1 times higher than that of Ca0.85Bi2Ta2O9：0.15Eu3＋.展开更多
基金financially supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea government Ministry of Trade,Industry&Energy(No.20184030202260)。
文摘Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,K),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state reaction.All the prepared phosphors formed a rhombohedral unit cell with the R3c space group.To improve the photoluminescence(PL)properties of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor,monovalent charge compensators such as Li^(+),NA^(+),and K^(+)were added to the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.The charge compensators acted as fluxes,so they improved the crystallinity.The excitation and emission properties were significantly improved through the incorporation of charge compensators.In particular,among the charge compensators,Li^(+)ion substantially enhanced the emission intensity and color purity.Furthermore,considering the evaporation of Li_(2)CO_(3)during the annealing process,we optimized the concentration of Li^(+)charge compensator to enhance its PL performance.Impressively,the green emission intensity of the Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.385 Li^(+)phosphor was 260%higher than that of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.We believe that the effect of charge compensators on the PL properties and the optimum concentration of Li^(+)cha rge compensator are useful for the design of phosphors in light-emitting diodes.
基金supported by Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)+5 种基金the 111 roject, Joint International Research Laboratory of Carbon-Based Functional Materials and Devicesthe National Natural Science Foundation of China (11905154)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (19KJA550004)the Natural Science Foundation of Jiangsu Province (BK20190814)the National Key R&D Program of China (No. 2016YFA0202600)supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231。
文摘Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demonstrated as a promising high-rate cathode material meeting the above requirements.Herein,we report the carbon decorated Li_(3)V_(2)(PO_(4))_(3) (LVP/C) cathode prepared via a facile method,which displays a remarkable high-rate capability and long-term cycling performance.Briefly,the prepared LVP/C delivers a high discharge capacity of 122 mAh g^(-1)(-93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles.Importantly,by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering,we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers.We show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles,which should be responsible for the remarkable electrochemical performance of LVP/C.Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP,which should be beneficial for the further design of high-performance LVP electrode materials.
文摘A deep trench super-junction LDMOS with double charge compensation layer(DC DT SJ LDMOS)is proposed in this paper.Due to the capacitance effect of the deep trench which is known as silicon-insulator-silicon(SIS)capacitance,the charge balance in the super-junction region of the conventional deep trench SJ LDMOS(Con.DT SJ LDMOS)device will be broken,resulting in breakdown voltage(BV)of the device drops.DC DT SJ LDMOS solves the SIS capacitance effect by adding a vertical variable doped charge compensation layer and a triangular charge compensation layer inside the Con.DT SJ LDMOS device.Therefore,the drift region reaches an ideal charge balance state again.The electric field is optimized by double charge compensation and gate field plate so that the breakdown voltage of the proposed device is improved sharply,meanwhile the enlarged on-current region reduces its specific on-resistance.The simulation results show that compared with the Con.DT SJ LD-MOS,the BV of the DC DT SJ LDMOS has been increased from 549.5 to 705.5 V,and the R_(on,sp) decreased to 23.7 mΩ·cm^(2).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21503263,U1632269,21473235,and 11227902)
文摘In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles are studied by soft x-ray absorption spectroscopy in total electron（TEY） and fluorescence（TFY） detection modes, which provide surface and bulk information, respectively. The spectra of Co L2,3-edge indicate that Co contributes to charge compensation below 4.4 V.Combining with the spectra of O K-edge, it manifests that only O contributes to electron compensation above 4.4 V with the formation of local O 2 p holes both on the surface and in the bulk, where the surficial O evolves more remarkably. The evolution of the O 2 p holes gives an explanation to the origin of O2^-or even O2. A comparison between the TEY and TFY of O K-edge spectra of LiCoO2 cycled in a range from 3 V to 4.6 V indicates both the structural change in the bulk and aggregation of lithium salts on the electrode surface are responsible for the capacity fading. However, the latter is found to play a more important role after many cycles.
基金supported by the National Natural Science Foundation of China(81303246)the Jiangsu Provincial Natural Science Foundation of China(BK2011815)+1 种基金the ‘Qing Lan’ Project from Jiangsu Provincial Framework Teacher Support Schemethe Projects of priority-discipline for colleges and universities of Jiangsu Province
文摘AIM: Variation in structure-related components in plant products prompted the trend to establish methods, using multiple or total analog analysis, for their effective quality control. However, the general use of routine quality control is restricted by the limited availability of reference substances. Using an easily available single marker as a reference standard to determine multiple or total analogs should be a practical option. METHOD: In this study, the Ultra-HPLC method was used for the baseline separation of the main components in ginseng extracts. Using a plant chemical component database, ginsenosides in ginseng extracts were identified by Ultra-HPLC-MS analysis. The charged aerosol detection(CAD) system with post-column compensation of the gradient generates a similar response for identical amounts of different analytes, and thus, the content of each ginsenoside in ginseng extracts was determined by comparing the analyte peak area with the reference standard(determination of total analogs by single marker, DTSM). The total ginsenoside content was determined by the summation of reference standard and other ginsenoside components. RESULTS: The results showed that DTSM approaches were available for the determination of total ginsenosides in a high purity ginseng extract because of the removal of impurities. In contrast, DTSM approaches might be suitable for determination of multiple ginsenosides without interference from impurities in the crude ginseng extract. CONCLUSION: Future practical studies similar to the present study should be conducted to verify that DTSM approaches based on CAD with post-column inverse gradient for uniform response are ideal for the quality control of plant products.
基金supported by the National Key Research and Development Program of China(2021YFA1500502)。
文摘The relationship between the structural evolution and redox of Li-rich transition-metal layered oxides(LLOs)cathodes remains ambiguous,obstructing the development of high-performance lithium-ion(Li^(+))battery.Herein,the coherent effects of local atomic and electronic structure in Li_(2)Ru_(x)Mn_(1-x)O_(3)(LRMO)with a wide voltage window(1.3–4.8 V)is identified by in situ X-ray absorption fine spectroscopy(XAFS)and chemometrics.We not only skillfully separated the redox active structures to track the electrochemical path,but also visualized the coupling mechanism between the evolution of Ru-Ru dimer and the(de)excitation of cations and anions.Furthermore,introducing manganese triggers the“heterogeneity”of coordination environment and electronic structure between Ru and Mn after discharge to 3 V.The change of thermodynamic and kinetic paths affects the relithiation,and further leads to the hysteresis of the anion activation structure relaxation of Li_(2)Ru_(0.4)Mn_(0.6)O_(3)relative to Li_(2)RuO_(3)(LRO).Additionally,it is demonstrated that the high charge cut-off voltage restrains the relaxation of anionic active structure in LRO from a new perspective through comparative experiments.Our work associates the evolution of atomic structure with charge compensation and negative electrochemical reactions such as voltage hysteresis(VH)and capacity attenuation,deepening the understanding electrochemical reaction mechanism of LLOs during the first cycle and providing a theoretical support for the further design and synthesis of high-efficiency cathodes.
基金supported by the National Natural Science Foundation of China(Grant No.61404110)the National Higher-education Institution General Research and Development Project(Grant No.2682014CX097)。
文摘An analytical model of the power metal–oxide–semiconductor field-effect transistor(MOSFET)with high permittivity insulator structure(HKMOS)with interface charge is established based on superposition and developed for optimization by charge compensation.In light of charge compensation,the disturbance aroused by interface charge is efficiently compromised by introducing extra charge for maximizing breakdown voltage(BV)and minimizing specific ON-resistance(R_(on,sp)).From this optimization method,it is very efficient to obtain the design parameters to overcome the difficulty in implementing the R_(on,sp)–BV trade-off for quick design.The analytical results prove that in the HKMOS with positive or negative interface charge at a given length of drift region,the extraction of the parameters is qualitatively and quantitatively optimized for trading off BV and Ron,sp with JFET effect taken into account.
基金supported by National Natural Science Foundation of China(No.51177020)
文摘Based on particle-in-cell simulation, we studied the motions of ions and electrons. The results have shown that electrons are bounded by a magnetic field and only a small number of electrons can pass through the whirler channel. The plasma becomes non-neutral when it is emitted from the whirler, and the spatial charge leads to a beam divergence, which is unfavorable for mass separation. In order to compensate the spatial charge, a cathode is designed to transmit electrons and the quasi-neutral plasma beam. Experiment results have demonstrated that the auxiliary cathode can obviously improve the compensation degree of the spatial charge.
基金This work was supported by the National Key Basic Research Program of China （No.2013CB921800）, the National Natural Science Foundation of China （No.11374291, No.11311120047, No.11274299, No.11447197, and No.11204292）, the Fundamen- tal Research Funds for the Central Universities （No.WK20304200）, the Anhui Provincial Natural Science Foundation （No.1508085QA09）. The numerical calculations have been partially done on the super- computing system in the Supercomputing Center of University of Science and Technology of China.
文摘Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3＋ centers in Ca3Sc2Si3O12 by considering the effects of the charge com- pensations related to N3-, Sc3＋, Mn2＋, Mg2＋, and Na＋. Firstly, the local structures around Ce3＋ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce3＋ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3＋-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3＋ substituting Si4＋. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.
基金Project supported by Natural Science Foundation of Fujian Province (2011J033)
文摘K2Ba（MoO4）2：Eu3＋ phosphors were synthesized by solid-state reaction. The emission and excitation spectra of K2 Ba（MoO4）2：Eu3＋ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet （394 nm） and blue （465 nm） light, and emitted red light at 616 nm. The influence of Eu3＋concentration, sintering temperature and charge compensators （K＋, Na＋ or Li＋ ） on the emission intensity were investigated. The results indicated that concentration quenching of Eu3＋ was not observed within 30mol.% Eu 3＋, 600 oC was a suitable sintering temperature for preparation of K2 Ba（MoO4）2：Eu3＋phosphors, and K＋ ions gave the best improvement to enhance the emission intensity. The CIE chromaticity coordinates of K2 Ba（MoO4）2：0.05Eu3＋phosphor were calculated to be （0.68, 0.32）, and color purity was 97.4%.
文摘In the present study,Sm^(3+)activated inorganic orthophosphate CsMgPO_(4)(CSMP)phosphors were prepared by adopting a solid-state reaction method.The structural phase purity and morphological features were studied by X-ray powder diffraction(XRD)and scanning electron microscopy(SEM),respectively.The molecular structure and vibrational modes were substantiated with the Fourier transform infrared spectroscopy(FTIR)and Raman spectroscopy characterization.The optical bandgap of the host and Sm^(3+)doped phosphors was deduced from the diffused reflectance(DR)spectra with a typical value of 5.72 eV and a small variation is observed with increasing concentrations.A systematic study of photoluminescence(PL)properties of Sm^(3+)doped CSMP phosphors was carried out.From the room temperature excitation and emission spectra,it is found that the phosphor emits in the orange rich red light under the suitable excitation of 402 nm in the UV region and concentration quenching occurs at x=0.02 doping level.The emission peaks observed at around 562,598 and 644 nm confirm the characteristic Sm^(3+)4 f-4 f transitions.The temperature-dependent photoluminescence(TD-PL)of the x=0.02(optimum doping)is recorded from 30 to 210℃,showing good thermal stability even at 150℃.The thermal quenching mechanisms are discussed based on the configuration coordinate model of excitation and emission.The prepared phosphors are found to exhibit near thermal stability compared to the commercially available red phosphors.PL decay time and quantum efficiency were measured.The colour coordinates are found to lie in the orangish-red region of the colour space.Thus the prepared phosphors CSMP:x Sm^(3+)can be useful as a red component in designing UV excitable chip-based phosphor-converted white LED applications.
基金Project supported by the Fundamental Research Funds for the Cornell University(30919011220)the Key Project of Jiangsu Province Programs for Research and Development(BE2019115)+1 种基金Top-notch Academic Programs Project of Jiangsu Higher Education InstitutionsChina-Finland Industrial R&D Program(BZ2018015)。
文摘In this study,K_(x)-Mn-Ce catalysts prepared by sol-gel method were investigated for toluene oxidation.Compared with Mn-Ce,the catalytic performance of K_(x)-Mn-Ce was further improved.X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM)and Raman analyses demonstrate that K ions enter the lattice of CeO_(2) and disperse uniformly.The results of X-ray photoelectron spectroscopy(XPS),H_(2)-temperature programmed reduction(H_(2)-TPR).and O_(2)-temperature programmed desorption(O_(2)-TPD)analyses indicate that there is a strong interaction between K,Mn and Ce;the charge co mpensation effect would be induced when K ions enter the lattice of CeO_(2),which leads to more oxygen vacancies due to the generation of more Ce^(3+).Toluene-TPD shows that K-doping enhances the activation ability of toluene.Among all catalysts,K0.1-Mn-Ce shows the highest concentration of Mn^(4+),Ce^(3+),Osur,and redox ability,resulting in higher low-temperature catalytic activity.Additionally,the results of stability and water resistance also prove that K0.1-Mn-Ce catalyst possesses excellent stability and water resistance.
基金supported by the National Natural Science Foundation of China(21205092,51474170)the National High-tech Research and Development Program of China(863 Program)(2011AA05A202)
文摘Trivalent samarium doped barium molybdate (BaMoO4:Sm3+) red phosphor was successfully synthesized by hydrothermal method. The crystal structure, morphology and photoluminescent property were characterized by X-ray diffraction, field environ-mental scanning electron microscopy and photoluminescence spectroscopy. The results indicated that the synthesized BaMoO4:Sm3+ phosphor consisted of a pure phase with an octahedral structure. The main excitation peaks were located at 362, 404, 445 and 477 nm, respectively, and were obviously observed. The main emission peaks were located at 533, 566, 602 and 646 nm, respectively. The phosphors exhibited a red performance at 646 nm, which was appropriate for the ultraviolet-light emitting diode (UV-LED) and blue LED. The luminescent intensity of BaMoO4:Sm3+ increased with an increase in the doping amount of Sm3+. The luminescent intensity had the optimal value forx=0.03. When the doping amount of Sm3+ was further increased, the concentration quenching phenomenon was observed. Monovalent lithium (Li+) cation was used as a charge compensator. The luminescence intensity first increased with in-creasing Li+ doping concentration, and then decreased. The optimal content of Li+ was about 2%. The BaMoO4:Sm3+ phosphor pre-pared in this study could act as superior red phosphor for white LEDs.
基金Sponsored by National Natural Science Foundation of China(51090384)
文摘The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to AP＋ in the molten slags, so that the deviations between the calculated values and measured ones of sulfide capacity are inevitable. The relation between sulfide capacity and the corrected optical basicity put forward by Mills considering the charge compensation was investigated. Combined with the relation be- tween sulfide capacity and temperatures, a novel and accurate calculation model of sulfide capacity was proposed, which was applied to calculate the sulfide capacities of CaO-Al2 O3-SiO2-MgO and CaO-Al2 03-SiO2-MgO-TiO2 sys-tems, where the sum of the CaO and MgO concentrations in the slags must be not lower than the Al2O3 concentra tion. It was also found that the calculated values were in a good agreement with the measured values, and the mean deviations were 2.57% and 2.65%, respectively.
基金Project supported by Hebei University Postdoctoral Research Station of Optical Engineering and Natural Science Foundation of Hebei Province (A2010000184)
文摘A series of CaMoO4 phosphors doped with trivalent dysprosium ions （Dy3＋） and lithium （Li＋） were prepared by solid state method at 750 °C for 3 h. X-ray diffraction （XRD） confirmed the crystal structure and quality of phosphors. Scanning electron microscopy （SEM） in- dicated that the phosphors presented good crystalline state, and the crystalline grain sizes were about 0.5–3.0 μm. The emission spectra showed that the phosphors had intense emission at 480 （4F9/2→6H15/2）, 576 （4F9/2→6H13/2） and 660 nm （4F9/2→6H11/2）. Meanwhile, the excited spectra indicated it had intense excitation at 352 （6H15/2→6P7/2）, 390 （6H15/2→4M21/2） and 450 nm （6H15/2→4I15/2）. As a charge compensator, Li＋ ions were incorporated into CaMoO4：Dy3＋ phosphors, which enhanced the PL intensities depending on the doping concentration of Li＋. The optimal molar fraction of Dy3＋ ions in Ca1-xMoO4：xDy3＋, 0.05Li＋ was 0.05.
基金supported by the National Natural Science Foundation of China (No.51090384)
文摘Viscosity is an important physical property of blast furnace slags and has a great influence on blast furnace operations. Because of time consumption and difficulties encountered during high temperature experimental measurement, viscosity data are also limited, so a rea-sonable and accurate estimation model is required to provide the data for controlling and optimizing the blast furnace process. In the present study a viscosity model was proposed for blast furnace slags. In the model the activation energy was calculated by the optical basicity cor-rected for cations required for the charge compensation of , and the temperature dependence was described by the Weymann-Frenkel equation. The estimated viscosity values of the CaO-Al2O3-SiO2, CaO-Al2O3-SiO2-MgO, and CaO-Al2O3-SiO2-MgO-TiO2 systems fit well with experiment data, with the mean deviation less than 25%.
基金The Natural Science Foundation of Shaan'xi Province(2005F06)
文摘The SrTiO3 ： Pr^3＋ material, co-doped with monovalent Li^＋ , divalent Mg^2＋ , and trivalent Al^3＋ was prepared by a new sol-gel method. The phase and crystallinity of the synthesized materials were investigated by powder X-ray diffraction（XRD） and scanning electron microcopy（SEM）. Among the co-doped ion, Al^3＋ incorporation caused the least lattice change and had the best crystallinity. Photoluminescence spectra were taken to investigate the luminescence characteristics. We observed a red luminescence change of SrTiO3 ： Pr^3＋ after being co-doped, and a best enhancement on the red luminescence with the trivalent Al^3＋ was observed. The present results indicated that the charge defect associated with Al^3＋ has led to charge compensation of Pr^＋ and also implied that the charge defects（usually the second dopant ions replacing the A or B sites in the lattice） which are closer to PrSr^＋ contribute more to the red luminescence enhancement.
基金Project supported by the National Natural Science Foundation of China(51672063)。
文摘Blue-emitting phosphors Sr_(6)Ca_(4)(PO_(4))_(6) F_(2):Eu^(2+)(SCPF:Eu^(2+)),Sr_(6 )Ca_(4)(PO4)6 F_(2):Eu^(2+),Dy^(3+)(SCPF:Eu^(2+),Dy^(3+))and Sr_(6)Ca_(4)(PO4)6 F_(2):Eu^(2+),Dy^(3+),Si^(4+)(SCPF:Eu^(2+),Dy^(3+),Si^(4+)) with apatite structure were successfully synthesized by traditional solid-state reaction under reducing atmosphere.Eu^(2+),Dy^(3+) and Si^(4+)ions occupy the corresponding sites of Sr^(2+),Ca^(2+) and P5+.Strong broad blue photo luminescence band is exhibited in SCPF:Eu^(2+),Dy^(3+) phosphor ranging from 400 to 550 nm centered at 455 nm and Dy^(3+) ions are vital in creating traps.Emission intensity of Eu^(2+),Dy^(3+) co-doped SCPF:0.02 Eu^(2+),0.02 Dy^(3+) is about 1.8 times that of SCPF:0.02 Eu^(2+) and electron trap centers serve as energy transporting media.To further elucidate the formation and effect of the specific defect on the luminescence of SCPF:0.02 Eu^(2+),0.02 Dy^(3+) phosphor,the thermoluminescence properties,decay curves and thermal stability studies were performed while the Si^(4+)-P^(5+) charge compensated pho sphor SCPF:0.02 Eu^(2+),0.02 Dy^(3+),0.02 Si^(4+) was prepared as a contrast.All the results of present work indicate that Dy^(3+) co-doping can obviously enhance photoluminescence intensity of SCPF:0.02 Eu^(2+) by the electron traps generated by non-equivalence replacement of Dy^(3+)-Ca^(2+).
基金the National Natural Science Foundation of China(11774187,U1902218)National Key R&D Program of China(2018YFE0203400)+1 种基金Natural Science Foundation of Tianjin city(19JCYBJC17600)111 Project(B07013)。
文摘Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs_3Zn_(5.94)B_9O_(21):0.06Eu^(3+)possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li^(+)ions into the lattice,the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect.Then,under the stimulus of high temperature,the corresponding trap levels with a suitable depth(E=1.27 eV)will release electrons to recombine with the luminescent centers,compensating for the energy loss.The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.
基金supported by Science Research Plan Funds of Guizhou Province of China(2012-3005,2010-4005,2009-15,2010-2134,2011-2016)Fundamental Research Funds for the Guiyang City(2012101-2-4)Graduate Innovation Fund for Guizhou University(2013019)for the financial support
文摘A series of red-emitting phosphors of CaBi2Ta2O9：Pr3＋ and CaBi2Ta2O9：Eu3＋ were synthesized by the solid-state reaction method. The crystal structure and photoluminescence properties were investigated by X-ray diffraction （XRD） and photoluminescence spectra. The emission spectra showed that the red emission peaks were located at 622 nm for Pr3＋ and 615 nm for Eu3＋, respectively. The optimal doping concentrations for Ca1-xBi2Ta2O9：xPr3＋ and Ca1-yBi2Ta2O9：yEu3＋ were x=0.02 and y=0.15, respectively. The effect of fluxes （H3BO3, NH4F, CaCl2 and CaF2） and charge compensations （Li2CO3, Na2CO3 and K2CO3） on luminescent properties were investigated in detail. It was found that the relative emission intensity of Ca0.98Bi2Ta2O9：0.02Pr3＋ with 10 mol.% H3BO3 flux was about 2.9 times higher than that of the sample without flux. The relative emission intensity of Ca0.7Bi2Ta2O9：0.15Eu3＋, 0.15K＋ was about the 2.1 times higher than that of Ca0.85Bi2Ta2O9：0.15Eu3＋.
